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Linus Torvalds1da177e2005-04-16 15:20:36 -07001
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002 Linux Ethernet Bonding Driver HOWTO
3
Ben Hutchingsad246c92011-04-26 15:25:52 +00004 Latest update: 27 April 2011
Linus Torvalds1da177e2005-04-16 15:20:36 -07005
6Initial release : Thomas Davis <tadavis at lbl.gov>
7Corrections, HA extensions : 2000/10/03-15 :
8 - Willy Tarreau <willy at meta-x.org>
9 - Constantine Gavrilov <const-g at xpert.com>
10 - Chad N. Tindel <ctindel at ieee dot org>
11 - Janice Girouard <girouard at us dot ibm dot com>
12 - Jay Vosburgh <fubar at us dot ibm dot com>
13
14Reorganized and updated Feb 2005 by Jay Vosburgh
Auke Kok6224e012006-06-08 11:15:35 -070015Added Sysfs information: 2006/04/24
16 - Mitch Williams <mitch.a.williams at intel.com>
Linus Torvalds1da177e2005-04-16 15:20:36 -070017
Jay Vosburgh00354cf2005-07-21 12:18:02 -070018Introduction
19============
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
Jay Vosburgh00354cf2005-07-21 12:18:02 -070021 The Linux bonding driver provides a method for aggregating
22multiple network interfaces into a single logical "bonded" interface.
23The behavior of the bonded interfaces depends upon the mode; generally
24speaking, modes provide either hot standby or load balancing services.
25Additionally, link integrity monitoring may be performed.
26
27 The bonding driver originally came from Donald Becker's
28beowulf patches for kernel 2.0. It has changed quite a bit since, and
29the original tools from extreme-linux and beowulf sites will not work
30with this version of the driver.
31
32 For new versions of the driver, updated userspace tools, and
33who to ask for help, please follow the links at the end of this file.
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
35Table of Contents
36=================
37
381. Bonding Driver Installation
39
402. Bonding Driver Options
41
423. Configuring Bonding Devices
Auke Kok6224e012006-06-08 11:15:35 -0700433.1 Configuration with Sysconfig Support
443.1.1 Using DHCP with Sysconfig
453.1.2 Configuring Multiple Bonds with Sysconfig
463.2 Configuration with Initscripts Support
473.2.1 Using DHCP with Initscripts
483.2.2 Configuring Multiple Bonds with Initscripts
493.3 Configuring Bonding Manually with Ifenslave
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700503.3.1 Configuring Multiple Bonds Manually
Auke Kok6224e012006-06-08 11:15:35 -0700513.4 Configuring Bonding Manually via Sysfs
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000523.5 Configuration with Interfaces Support
533.6 Overriding Configuration for Special Cases
Mahesh Bandeward22a5fc2015-05-09 00:01:57 -0700543.7 Configuring LACP for 802.3ad mode in a more secure way
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
Auke Kok6224e012006-06-08 11:15:35 -0700564. Querying Bonding Configuration
574.1 Bonding Configuration
584.2 Network Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
Auke Kok6224e012006-06-08 11:15:35 -0700605. Switch Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
Auke Kok6224e012006-06-08 11:15:35 -0700626. 802.1q VLAN Support
Linus Torvalds1da177e2005-04-16 15:20:36 -070063
Auke Kok6224e012006-06-08 11:15:35 -0700647. Link Monitoring
657.1 ARP Monitor Operation
667.2 Configuring Multiple ARP Targets
677.3 MII Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -070068
Auke Kok6224e012006-06-08 11:15:35 -0700698. Potential Trouble Sources
708.1 Adventures in Routing
718.2 Ethernet Device Renaming
728.3 Painfully Slow Or No Failed Link Detection By Miimon
Linus Torvalds1da177e2005-04-16 15:20:36 -070073
Auke Kok6224e012006-06-08 11:15:35 -0700749. SNMP agents
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
Auke Kok6224e012006-06-08 11:15:35 -07007610. Promiscuous mode
Linus Torvalds1da177e2005-04-16 15:20:36 -070077
Auke Kok6224e012006-06-08 11:15:35 -07007811. Configuring Bonding for High Availability
7911.1 High Availability in a Single Switch Topology
8011.2 High Availability in a Multiple Switch Topology
8111.2.1 HA Bonding Mode Selection for Multiple Switch Topology
8211.2.2 HA Link Monitoring for Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -070083
Auke Kok6224e012006-06-08 11:15:35 -07008412. Configuring Bonding for Maximum Throughput
8512.1 Maximum Throughput in a Single Switch Topology
8612.1.1 MT Bonding Mode Selection for Single Switch Topology
8712.1.2 MT Link Monitoring for Single Switch Topology
8812.2 Maximum Throughput in a Multiple Switch Topology
8912.2.1 MT Bonding Mode Selection for Multiple Switch Topology
9012.2.2 MT Link Monitoring for Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -070091
Auke Kok6224e012006-06-08 11:15:35 -07009213. Switch Behavior Issues
9313.1 Link Establishment and Failover Delays
9413.2 Duplicated Incoming Packets
Linus Torvalds1da177e2005-04-16 15:20:36 -070095
Auke Kok6224e012006-06-08 11:15:35 -07009614. Hardware Specific Considerations
9714.1 IBM BladeCenter
Jay Vosburgh00354cf2005-07-21 12:18:02 -070098
Auke Kok6224e012006-06-08 11:15:35 -07009915. Frequently Asked Questions
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700100
Auke Kok6224e012006-06-08 11:15:35 -070010116. Resources and Links
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102
103
1041. Bonding Driver Installation
105==============================
106
107 Most popular distro kernels ship with the bonding driver
Cong Wangb1098bb2013-05-27 15:49:16 +0000108already available as a module. If your distro does not, or you
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109have need to compile bonding from source (e.g., configuring and
110installing a mainline kernel from kernel.org), you'll need to perform
111the following steps:
112
1131.1 Configure and build the kernel with bonding
114-----------------------------------------------
115
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700116 The current version of the bonding driver is available in the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117drivers/net/bonding subdirectory of the most recent kernel source
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700118(which is available on http://kernel.org). Most users "rolling their
119own" will want to use the most recent kernel from kernel.org.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120
121 Configure kernel with "make menuconfig" (or "make xconfig" or
122"make config"), then select "Bonding driver support" in the "Network
123device support" section. It is recommended that you configure the
124driver as module since it is currently the only way to pass parameters
125to the driver or configure more than one bonding device.
126
Cong Wangb1098bb2013-05-27 15:49:16 +0000127 Build and install the new kernel and modules.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128
Cong Wangb1098bb2013-05-27 15:49:16 +00001291.2 Bonding Control Utility
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130-------------------------------------
131
Cong Wangb1098bb2013-05-27 15:49:16 +0000132 It is recommended to configure bonding via iproute2 (netlink)
133or sysfs, the old ifenslave control utility is obsolete.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134
1352. Bonding Driver Options
136=========================
137
Jay Vosburgh9a6c6862007-11-13 20:25:48 -0800138 Options for the bonding driver are supplied as parameters to the
139bonding module at load time, or are specified via sysfs.
140
141 Module options may be given as command line arguments to the
142insmod or modprobe command, but are usually specified in either the
Lucas De Marchi970e2482012-03-30 13:37:16 -0700143/etc/modrobe.d/*.conf configuration files, or in a distro-specific
144configuration file (some of which are detailed in the next section).
Jay Vosburgh9a6c6862007-11-13 20:25:48 -0800145
146 Details on bonding support for sysfs is provided in the
147"Configuring Bonding Manually via Sysfs" section, below.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148
149 The available bonding driver parameters are listed below. If a
150parameter is not specified the default value is used. When initially
151configuring a bond, it is recommended "tail -f /var/log/messages" be
152run in a separate window to watch for bonding driver error messages.
153
154 It is critical that either the miimon or arp_interval and
155arp_ip_target parameters be specified, otherwise serious network
156degradation will occur during link failures. Very few devices do not
157support at least miimon, so there is really no reason not to use it.
158
159 Options with textual values will accept either the text name
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700160or, for backwards compatibility, the option value. E.g.,
161"mode=802.3ad" and "mode=4" set the same mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700162
163 The parameters are as follows:
164
Nicolas de Pesloüan1ba9ac72011-12-26 13:35:24 +0000165active_slave
166
167 Specifies the new active slave for modes that support it
168 (active-backup, balance-alb and balance-tlb). Possible values
169 are the name of any currently enslaved interface, or an empty
170 string. If a name is given, the slave and its link must be up in order
171 to be selected as the new active slave. If an empty string is
172 specified, the current active slave is cleared, and a new active
173 slave is selected automatically.
174
175 Note that this is only available through the sysfs interface. No module
176 parameter by this name exists.
177
178 The normal value of this option is the name of the currently
179 active slave, or the empty string if there is no active slave or
180 the current mode does not use an active slave.
181
Mahesh Bandewar6791e462015-05-09 00:01:55 -0700182ad_actor_sys_prio
183
184 In an AD system, this specifies the system priority. The allowed range
185 is 1 - 65535. If the value is not specified, it takes 65535 as the
186 default value.
187
188 This parameter has effect only in 802.3ad mode and is available through
189 SysFs interface.
190
Mahesh Bandewar74514952015-05-09 00:01:56 -0700191ad_actor_system
192
193 In an AD system, this specifies the mac-address for the actor in
194 protocol packet exchanges (LACPDUs). The value cannot be NULL or
195 multicast. It is preferred to have the local-admin bit set for this
196 mac but driver does not enforce it. If the value is not given then
197 system defaults to using the masters' mac address as actors' system
198 address.
199
200 This parameter has effect only in 802.3ad mode and is available through
201 SysFs interface.
202
Jay Vosburghfd989c82008-11-04 17:51:16 -0800203ad_select
204
205 Specifies the 802.3ad aggregation selection logic to use. The
206 possible values and their effects are:
207
208 stable or 0
209
210 The active aggregator is chosen by largest aggregate
211 bandwidth.
212
213 Reselection of the active aggregator occurs only when all
214 slaves of the active aggregator are down or the active
215 aggregator has no slaves.
216
217 This is the default value.
218
219 bandwidth or 1
220
221 The active aggregator is chosen by largest aggregate
222 bandwidth. Reselection occurs if:
223
224 - A slave is added to or removed from the bond
225
226 - Any slave's link state changes
227
228 - Any slave's 802.3ad association state changes
229
Matt LaPlante19f59462009-04-27 15:06:31 +0200230 - The bond's administrative state changes to up
Jay Vosburghfd989c82008-11-04 17:51:16 -0800231
232 count or 2
233
234 The active aggregator is chosen by the largest number of
235 ports (slaves). Reselection occurs as described under the
236 "bandwidth" setting, above.
237
238 The bandwidth and count selection policies permit failover of
239 802.3ad aggregations when partial failure of the active aggregator
240 occurs. This keeps the aggregator with the highest availability
241 (either in bandwidth or in number of ports) active at all times.
242
243 This option was added in bonding version 3.4.0.
244
Mahesh Bandeward22a5fc2015-05-09 00:01:57 -0700245ad_user_port_key
246
247 In an AD system, the port-key has three parts as shown below -
248
249 Bits Use
250 00 Duplex
251 01-05 Speed
252 06-15 User-defined
253
254 This defines the upper 10 bits of the port key. The values can be
255 from 0 - 1023. If not given, the system defaults to 0.
256
257 This parameter has effect only in 802.3ad mode and is available through
258 SysFs interface.
259
Nicolas de Pesloüan025890b2011-08-06 07:06:39 +0000260all_slaves_active
261
262 Specifies that duplicate frames (received on inactive ports) should be
263 dropped (0) or delivered (1).
264
265 Normally, bonding will drop duplicate frames (received on inactive
266 ports), which is desirable for most users. But there are some times
267 it is nice to allow duplicate frames to be delivered.
268
269 The default value is 0 (drop duplicate frames received on inactive
270 ports).
271
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272arp_interval
273
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700274 Specifies the ARP link monitoring frequency in milliseconds.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700275
276 The ARP monitor works by periodically checking the slave
277 devices to determine whether they have sent or received
278 traffic recently (the precise criteria depends upon the
279 bonding mode, and the state of the slave). Regular traffic is
280 generated via ARP probes issued for the addresses specified by
281 the arp_ip_target option.
282
283 This behavior can be modified by the arp_validate option,
284 below.
285
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700286 If ARP monitoring is used in an etherchannel compatible mode
287 (modes 0 and 2), the switch should be configured in a mode
288 that evenly distributes packets across all links. If the
289 switch is configured to distribute the packets in an XOR
Linus Torvalds1da177e2005-04-16 15:20:36 -0700290 fashion, all replies from the ARP targets will be received on
291 the same link which could cause the other team members to
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700292 fail. ARP monitoring should not be used in conjunction with
293 miimon. A value of 0 disables ARP monitoring. The default
Linus Torvalds1da177e2005-04-16 15:20:36 -0700294 value is 0.
295
296arp_ip_target
297
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700298 Specifies the IP addresses to use as ARP monitoring peers when
299 arp_interval is > 0. These are the targets of the ARP request
300 sent to determine the health of the link to the targets.
301 Specify these values in ddd.ddd.ddd.ddd format. Multiple IP
302 addresses must be separated by a comma. At least one IP
303 address must be given for ARP monitoring to function. The
304 maximum number of targets that can be specified is 16. The
305 default value is no IP addresses.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700306
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700307arp_validate
308
309 Specifies whether or not ARP probes and replies should be
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100310 validated in any mode that supports arp monitoring, or whether
311 non-ARP traffic should be filtered (disregarded) for link
312 monitoring purposes.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700313
314 Possible values are:
315
316 none or 0
317
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100318 No validation or filtering is performed.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700319
320 active or 1
321
322 Validation is performed only for the active slave.
323
324 backup or 2
325
326 Validation is performed only for backup slaves.
327
328 all or 3
329
330 Validation is performed for all slaves.
331
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100332 filter or 4
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700333
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100334 Filtering is applied to all slaves. No validation is
335 performed.
Veaceslav Falicod7d35c62013-06-24 11:49:33 +0200336
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100337 filter_active or 5
338
339 Filtering is applied to all slaves, validation is performed
340 only for the active slave.
341
342 filter_backup or 6
343
344 Filtering is applied to all slaves, validation is performed
345 only for backup slaves.
346
347 Validation:
348
349 Enabling validation causes the ARP monitor to examine the incoming
350 ARP requests and replies, and only consider a slave to be up if it
351 is receiving the appropriate ARP traffic.
352
353 For an active slave, the validation checks ARP replies to confirm
354 that they were generated by an arp_ip_target. Since backup slaves
355 do not typically receive these replies, the validation performed
356 for backup slaves is on the broadcast ARP request sent out via the
357 active slave. It is possible that some switch or network
358 configurations may result in situations wherein the backup slaves
359 do not receive the ARP requests; in such a situation, validation
360 of backup slaves must be disabled.
361
362 The validation of ARP requests on backup slaves is mainly helping
363 bonding to decide which slaves are more likely to work in case of
364 the active slave failure, it doesn't really guarantee that the
365 backup slave will work if it's selected as the next active slave.
366
367 Validation is useful in network configurations in which multiple
368 bonding hosts are concurrently issuing ARPs to one or more targets
369 beyond a common switch. Should the link between the switch and
370 target fail (but not the switch itself), the probe traffic
371 generated by the multiple bonding instances will fool the standard
372 ARP monitor into considering the links as still up. Use of
373 validation can resolve this, as the ARP monitor will only consider
374 ARP requests and replies associated with its own instance of
375 bonding.
376
377 Filtering:
378
379 Enabling filtering causes the ARP monitor to only use incoming ARP
380 packets for link availability purposes. Arriving packets that are
381 not ARPs are delivered normally, but do not count when determining
382 if a slave is available.
383
384 Filtering operates by only considering the reception of ARP
385 packets (any ARP packet, regardless of source or destination) when
386 determining if a slave has received traffic for link availability
387 purposes.
388
389 Filtering is useful in network configurations in which significant
390 levels of third party broadcast traffic would fool the standard
391 ARP monitor into considering the links as still up. Use of
392 filtering can resolve this, as only ARP traffic is considered for
393 link availability purposes.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700394
395 This option was added in bonding version 3.1.0.
396
Veaceslav Falico8599b522013-06-24 11:49:34 +0200397arp_all_targets
398
399 Specifies the quantity of arp_ip_targets that must be reachable
400 in order for the ARP monitor to consider a slave as being up.
401 This option affects only active-backup mode for slaves with
402 arp_validation enabled.
403
404 Possible values are:
405
406 any or 0
407
408 consider the slave up only when any of the arp_ip_targets
409 is reachable
410
411 all or 1
412
413 consider the slave up only when all of the arp_ip_targets
414 are reachable
415
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416downdelay
417
418 Specifies the time, in milliseconds, to wait before disabling
419 a slave after a link failure has been detected. This option
420 is only valid for the miimon link monitor. The downdelay
421 value should be a multiple of the miimon value; if not, it
422 will be rounded down to the nearest multiple. The default
423 value is 0.
424
Jay Vosburghdd957c52007-10-09 19:57:24 -0700425fail_over_mac
426
427 Specifies whether active-backup mode should set all slaves to
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700428 the same MAC address at enslavement (the traditional
429 behavior), or, when enabled, perform special handling of the
430 bond's MAC address in accordance with the selected policy.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700431
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700432 Possible values are:
Jay Vosburghdd957c52007-10-09 19:57:24 -0700433
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700434 none or 0
Jay Vosburghdd957c52007-10-09 19:57:24 -0700435
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700436 This setting disables fail_over_mac, and causes
437 bonding to set all slaves of an active-backup bond to
438 the same MAC address at enslavement time. This is the
439 default.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700440
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700441 active or 1
Jay Vosburghdd957c52007-10-09 19:57:24 -0700442
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700443 The "active" fail_over_mac policy indicates that the
444 MAC address of the bond should always be the MAC
445 address of the currently active slave. The MAC
446 address of the slaves is not changed; instead, the MAC
447 address of the bond changes during a failover.
448
449 This policy is useful for devices that cannot ever
450 alter their MAC address, or for devices that refuse
451 incoming broadcasts with their own source MAC (which
452 interferes with the ARP monitor).
453
454 The down side of this policy is that every device on
455 the network must be updated via gratuitous ARP,
456 vs. just updating a switch or set of switches (which
457 often takes place for any traffic, not just ARP
458 traffic, if the switch snoops incoming traffic to
459 update its tables) for the traditional method. If the
460 gratuitous ARP is lost, communication may be
461 disrupted.
462
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300463 When this policy is used in conjunction with the mii
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700464 monitor, devices which assert link up prior to being
465 able to actually transmit and receive are particularly
Matt LaPlante19f59462009-04-27 15:06:31 +0200466 susceptible to loss of the gratuitous ARP, and an
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700467 appropriate updelay setting may be required.
468
469 follow or 2
470
471 The "follow" fail_over_mac policy causes the MAC
472 address of the bond to be selected normally (normally
473 the MAC address of the first slave added to the bond).
474 However, the second and subsequent slaves are not set
475 to this MAC address while they are in a backup role; a
476 slave is programmed with the bond's MAC address at
477 failover time (and the formerly active slave receives
478 the newly active slave's MAC address).
479
480 This policy is useful for multiport devices that
481 either become confused or incur a performance penalty
482 when multiple ports are programmed with the same MAC
483 address.
484
485
486 The default policy is none, unless the first slave cannot
487 change its MAC address, in which case the active policy is
488 selected by default.
489
490 This option may be modified via sysfs only when no slaves are
491 present in the bond.
492
493 This option was added in bonding version 3.2.0. The "follow"
494 policy was added in bonding version 3.3.0.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700495
Linus Torvalds1da177e2005-04-16 15:20:36 -0700496lacp_rate
497
498 Option specifying the rate in which we'll ask our link partner
499 to transmit LACPDU packets in 802.3ad mode. Possible values
500 are:
501
502 slow or 0
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700503 Request partner to transmit LACPDUs every 30 seconds
Linus Torvalds1da177e2005-04-16 15:20:36 -0700504
505 fast or 1
506 Request partner to transmit LACPDUs every 1 second
507
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700508 The default is slow.
509
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510max_bonds
511
512 Specifies the number of bonding devices to create for this
513 instance of the bonding driver. E.g., if max_bonds is 3, and
514 the bonding driver is not already loaded, then bond0, bond1
Jay Vosburghb8a97872008-06-13 18:12:04 -0700515 and bond2 will be created. The default value is 1. Specifying
516 a value of 0 will load bonding, but will not create any devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517
518miimon
519
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700520 Specifies the MII link monitoring frequency in milliseconds.
521 This determines how often the link state of each slave is
522 inspected for link failures. A value of zero disables MII
523 link monitoring. A value of 100 is a good starting point.
524 The use_carrier option, below, affects how the link state is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525 determined. See the High Availability section for additional
526 information. The default value is 0.
527
Nicolas de Pesloüan025890b2011-08-06 07:06:39 +0000528min_links
529
530 Specifies the minimum number of links that must be active before
531 asserting carrier. It is similar to the Cisco EtherChannel min-links
532 feature. This allows setting the minimum number of member ports that
533 must be up (link-up state) before marking the bond device as up
534 (carrier on). This is useful for situations where higher level services
535 such as clustering want to ensure a minimum number of low bandwidth
536 links are active before switchover. This option only affect 802.3ad
537 mode.
538
539 The default value is 0. This will cause carrier to be asserted (for
540 802.3ad mode) whenever there is an active aggregator, regardless of the
541 number of available links in that aggregator. Note that, because an
542 aggregator cannot be active without at least one available link,
543 setting this option to 0 or to 1 has the exact same effect.
544
Linus Torvalds1da177e2005-04-16 15:20:36 -0700545mode
546
547 Specifies one of the bonding policies. The default is
548 balance-rr (round robin). Possible values are:
549
550 balance-rr or 0
551
552 Round-robin policy: Transmit packets in sequential
553 order from the first available slave through the
554 last. This mode provides load balancing and fault
555 tolerance.
556
557 active-backup or 1
558
559 Active-backup policy: Only one slave in the bond is
560 active. A different slave becomes active if, and only
561 if, the active slave fails. The bond's MAC address is
562 externally visible on only one port (network adapter)
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700563 to avoid confusing the switch.
564
565 In bonding version 2.6.2 or later, when a failover
566 occurs in active-backup mode, bonding will issue one
567 or more gratuitous ARPs on the newly active slave.
Auke Kok6224e012006-06-08 11:15:35 -0700568 One gratuitous ARP is issued for the bonding master
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700569 interface and each VLAN interfaces configured above
570 it, provided that the interface has at least one IP
571 address configured. Gratuitous ARPs issued for VLAN
572 interfaces are tagged with the appropriate VLAN id.
573
574 This mode provides fault tolerance. The primary
575 option, documented below, affects the behavior of this
576 mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577
578 balance-xor or 2
579
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700580 XOR policy: Transmit based on the selected transmit
581 hash policy. The default policy is a simple [(source
Jianhua Xie92abf752014-07-17 14:16:26 +0800582 MAC address XOR'd with destination MAC address XOR
583 packet type ID) modulo slave count]. Alternate transmit
584 policies may be selected via the xmit_hash_policy option,
585 described below.
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700586
587 This mode provides load balancing and fault tolerance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700588
589 broadcast or 3
590
591 Broadcast policy: transmits everything on all slave
592 interfaces. This mode provides fault tolerance.
593
594 802.3ad or 4
595
596 IEEE 802.3ad Dynamic link aggregation. Creates
597 aggregation groups that share the same speed and
598 duplex settings. Utilizes all slaves in the active
599 aggregator according to the 802.3ad specification.
600
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700601 Slave selection for outgoing traffic is done according
602 to the transmit hash policy, which may be changed from
603 the default simple XOR policy via the xmit_hash_policy
604 option, documented below. Note that not all transmit
605 policies may be 802.3ad compliant, particularly in
606 regards to the packet mis-ordering requirements of
607 section 43.2.4 of the 802.3ad standard. Differing
608 peer implementations will have varying tolerances for
609 noncompliance.
610
611 Prerequisites:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612
613 1. Ethtool support in the base drivers for retrieving
614 the speed and duplex of each slave.
615
616 2. A switch that supports IEEE 802.3ad Dynamic link
617 aggregation.
618
619 Most switches will require some type of configuration
620 to enable 802.3ad mode.
621
622 balance-tlb or 5
623
624 Adaptive transmit load balancing: channel bonding that
Mahesh Bandeware9f0fb82014-04-22 16:30:22 -0700625 does not require any special switch support.
626
627 In tlb_dynamic_lb=1 mode; the outgoing traffic is
628 distributed according to the current load (computed
629 relative to the speed) on each slave.
630
631 In tlb_dynamic_lb=0 mode; the load balancing based on
632 current load is disabled and the load is distributed
633 only using the hash distribution.
634
635 Incoming traffic is received by the current slave.
636 If the receiving slave fails, another slave takes over
637 the MAC address of the failed receiving slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700638
639 Prerequisite:
640
641 Ethtool support in the base drivers for retrieving the
642 speed of each slave.
643
644 balance-alb or 6
645
646 Adaptive load balancing: includes balance-tlb plus
647 receive load balancing (rlb) for IPV4 traffic, and
648 does not require any special switch support. The
649 receive load balancing is achieved by ARP negotiation.
650 The bonding driver intercepts the ARP Replies sent by
651 the local system on their way out and overwrites the
652 source hardware address with the unique hardware
653 address of one of the slaves in the bond such that
654 different peers use different hardware addresses for
655 the server.
656
657 Receive traffic from connections created by the server
658 is also balanced. When the local system sends an ARP
659 Request the bonding driver copies and saves the peer's
660 IP information from the ARP packet. When the ARP
661 Reply arrives from the peer, its hardware address is
662 retrieved and the bonding driver initiates an ARP
663 reply to this peer assigning it to one of the slaves
664 in the bond. A problematic outcome of using ARP
665 negotiation for balancing is that each time that an
666 ARP request is broadcast it uses the hardware address
667 of the bond. Hence, peers learn the hardware address
668 of the bond and the balancing of receive traffic
669 collapses to the current slave. This is handled by
670 sending updates (ARP Replies) to all the peers with
671 their individually assigned hardware address such that
672 the traffic is redistributed. Receive traffic is also
673 redistributed when a new slave is added to the bond
674 and when an inactive slave is re-activated. The
675 receive load is distributed sequentially (round robin)
676 among the group of highest speed slaves in the bond.
677
678 When a link is reconnected or a new slave joins the
679 bond the receive traffic is redistributed among all
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700680 active slaves in the bond by initiating ARP Replies
Auke Kok6224e012006-06-08 11:15:35 -0700681 with the selected MAC address to each of the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700682 clients. The updelay parameter (detailed below) must
683 be set to a value equal or greater than the switch's
684 forwarding delay so that the ARP Replies sent to the
685 peers will not be blocked by the switch.
686
687 Prerequisites:
688
689 1. Ethtool support in the base drivers for retrieving
690 the speed of each slave.
691
692 2. Base driver support for setting the hardware
693 address of a device while it is open. This is
694 required so that there will always be one slave in the
695 team using the bond hardware address (the
696 curr_active_slave) while having a unique hardware
697 address for each slave in the bond. If the
698 curr_active_slave fails its hardware address is
699 swapped with the new curr_active_slave that was
700 chosen.
701
Jay Vosburghb59f9f72008-06-13 18:12:03 -0700702num_grat_arp
Brian Haley305d5522008-11-04 17:51:14 -0800703num_unsol_na
704
Ben Hutchingsad246c92011-04-26 15:25:52 +0000705 Specify the number of peer notifications (gratuitous ARPs and
706 unsolicited IPv6 Neighbor Advertisements) to be issued after a
707 failover event. As soon as the link is up on the new slave
708 (possibly immediately) a peer notification is sent on the
709 bonding device and each VLAN sub-device. This is repeated at
710 each link monitor interval (arp_interval or miimon, whichever
711 is active) if the number is greater than 1.
Brian Haley305d5522008-11-04 17:51:14 -0800712
Ben Hutchingsad246c92011-04-26 15:25:52 +0000713 The valid range is 0 - 255; the default value is 1. These options
714 affect only the active-backup mode. These options were added for
715 bonding versions 3.3.0 and 3.4.0 respectively.
716
Jesper Juhl8fb4e132011-08-01 17:59:44 -0700717 From Linux 3.0 and bonding version 3.7.1, these notifications
Ben Hutchingsad246c92011-04-26 15:25:52 +0000718 are generated by the ipv4 and ipv6 code and the numbers of
719 repetitions cannot be set independently.
Brian Haley305d5522008-11-04 17:51:14 -0800720
Nikolay Aleksandrov12465fb2013-11-05 13:51:42 +0100721packets_per_slave
722
723 Specify the number of packets to transmit through a slave before
724 moving to the next one. When set to 0 then a slave is chosen at
725 random.
726
727 The valid range is 0 - 65535; the default value is 1. This option
728 has effect only in balance-rr mode.
729
Linus Torvalds1da177e2005-04-16 15:20:36 -0700730primary
731
732 A string (eth0, eth2, etc) specifying which slave is the
733 primary device. The specified device will always be the
734 active slave while it is available. Only when the primary is
735 off-line will alternate devices be used. This is useful when
736 one slave is preferred over another, e.g., when one slave has
737 higher throughput than another.
738
dingtianhonge1d206a2014-01-18 16:28:57 +0800739 The primary option is only valid for active-backup(1),
740 balance-tlb (5) and balance-alb (6) mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700741
Jiri Pirkoa5499522009-09-25 03:28:09 +0000742primary_reselect
743
744 Specifies the reselection policy for the primary slave. This
745 affects how the primary slave is chosen to become the active slave
746 when failure of the active slave or recovery of the primary slave
747 occurs. This option is designed to prevent flip-flopping between
748 the primary slave and other slaves. Possible values are:
749
750 always or 0 (default)
751
752 The primary slave becomes the active slave whenever it
753 comes back up.
754
755 better or 1
756
757 The primary slave becomes the active slave when it comes
758 back up, if the speed and duplex of the primary slave is
759 better than the speed and duplex of the current active
760 slave.
761
762 failure or 2
763
764 The primary slave becomes the active slave only if the
765 current active slave fails and the primary slave is up.
766
767 The primary_reselect setting is ignored in two cases:
768
769 If no slaves are active, the first slave to recover is
770 made the active slave.
771
772 When initially enslaved, the primary slave is always made
773 the active slave.
774
775 Changing the primary_reselect policy via sysfs will cause an
776 immediate selection of the best active slave according to the new
777 policy. This may or may not result in a change of the active
778 slave, depending upon the circumstances.
779
780 This option was added for bonding version 3.6.0.
781
Mahesh Bandeware9f0fb82014-04-22 16:30:22 -0700782tlb_dynamic_lb
783
784 Specifies if dynamic shuffling of flows is enabled in tlb
785 mode. The value has no effect on any other modes.
786
787 The default behavior of tlb mode is to shuffle active flows across
788 slaves based on the load in that interval. This gives nice lb
789 characteristics but can cause packet reordering. If re-ordering is
790 a concern use this variable to disable flow shuffling and rely on
791 load balancing provided solely by the hash distribution.
792 xmit-hash-policy can be used to select the appropriate hashing for
793 the setup.
794
795 The sysfs entry can be used to change the setting per bond device
796 and the initial value is derived from the module parameter. The
797 sysfs entry is allowed to be changed only if the bond device is
798 down.
799
800 The default value is "1" that enables flow shuffling while value "0"
801 disables it. This option was added in bonding driver 3.7.1
802
803
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804updelay
805
806 Specifies the time, in milliseconds, to wait before enabling a
807 slave after a link recovery has been detected. This option is
808 only valid for the miimon link monitor. The updelay value
809 should be a multiple of the miimon value; if not, it will be
810 rounded down to the nearest multiple. The default value is 0.
811
812use_carrier
813
814 Specifies whether or not miimon should use MII or ETHTOOL
815 ioctls vs. netif_carrier_ok() to determine the link
816 status. The MII or ETHTOOL ioctls are less efficient and
817 utilize a deprecated calling sequence within the kernel. The
818 netif_carrier_ok() relies on the device driver to maintain its
819 state with netif_carrier_on/off; at this writing, most, but
820 not all, device drivers support this facility.
821
822 If bonding insists that the link is up when it should not be,
823 it may be that your network device driver does not support
824 netif_carrier_on/off. The default state for netif_carrier is
825 "carrier on," so if a driver does not support netif_carrier,
826 it will appear as if the link is always up. In this case,
827 setting use_carrier to 0 will cause bonding to revert to the
828 MII / ETHTOOL ioctl method to determine the link state.
829
830 A value of 1 enables the use of netif_carrier_ok(), a value of
831 0 will use the deprecated MII / ETHTOOL ioctls. The default
832 value is 1.
833
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700834xmit_hash_policy
835
836 Selects the transmit hash policy to use for slave selection in
Mahesh Bandewarf05b42e2014-04-22 16:30:20 -0700837 balance-xor, 802.3ad, and tlb modes. Possible values are:
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700838
839 layer2
840
Jianhua Xie92abf752014-07-17 14:16:26 +0800841 Uses XOR of hardware MAC addresses and packet type ID
842 field to generate the hash. The formula is
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700843
Jianhua Xie92abf752014-07-17 14:16:26 +0800844 hash = source MAC XOR destination MAC XOR packet type ID
845 slave number = hash modulo slave count
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700846
847 This algorithm will place all traffic to a particular
848 network peer on the same slave.
849
850 This algorithm is 802.3ad compliant.
851
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800852 layer2+3
853
854 This policy uses a combination of layer2 and layer3
855 protocol information to generate the hash.
856
857 Uses XOR of hardware MAC addresses and IP addresses to
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200858 generate the hash. The formula is
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800859
Jianhua Xie92abf752014-07-17 14:16:26 +0800860 hash = source MAC XOR destination MAC XOR packet type ID
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200861 hash = hash XOR source IP XOR destination IP
862 hash = hash XOR (hash RSHIFT 16)
863 hash = hash XOR (hash RSHIFT 8)
864 And then hash is reduced modulo slave count.
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800865
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200866 If the protocol is IPv6 then the source and destination
867 addresses are first hashed using ipv6_addr_hash.
John Eaglesham6b923cb2012-08-21 20:43:35 +0000868
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800869 This algorithm will place all traffic to a particular
870 network peer on the same slave. For non-IP traffic,
871 the formula is the same as for the layer2 transmit
872 hash policy.
873
874 This policy is intended to provide a more balanced
875 distribution of traffic than layer2 alone, especially
876 in environments where a layer3 gateway device is
877 required to reach most destinations.
878
Matt LaPlanted9195882008-07-25 19:45:33 -0700879 This algorithm is 802.3ad compliant.
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800880
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700881 layer3+4
882
883 This policy uses upper layer protocol information,
884 when available, to generate the hash. This allows for
885 traffic to a particular network peer to span multiple
886 slaves, although a single connection will not span
887 multiple slaves.
888
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200889 The formula for unfragmented TCP and UDP packets is
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700890
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200891 hash = source port, destination port (as in the header)
892 hash = hash XOR source IP XOR destination IP
893 hash = hash XOR (hash RSHIFT 16)
894 hash = hash XOR (hash RSHIFT 8)
895 And then hash is reduced modulo slave count.
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700896
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200897 If the protocol is IPv6 then the source and destination
898 addresses are first hashed using ipv6_addr_hash.
John Eaglesham6b923cb2012-08-21 20:43:35 +0000899
900 For fragmented TCP or UDP packets and all other IPv4 and
901 IPv6 protocol traffic, the source and destination port
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700902 information is omitted. For non-IP traffic, the
903 formula is the same as for the layer2 transmit hash
904 policy.
905
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700906 This algorithm is not fully 802.3ad compliant. A
907 single TCP or UDP conversation containing both
908 fragmented and unfragmented packets will see packets
909 striped across two interfaces. This may result in out
910 of order delivery. Most traffic types will not meet
911 this criteria, as TCP rarely fragments traffic, and
912 most UDP traffic is not involved in extended
913 conversations. Other implementations of 802.3ad may
914 or may not tolerate this noncompliance.
915
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200916 encap2+3
917
918 This policy uses the same formula as layer2+3 but it
919 relies on skb_flow_dissect to obtain the header fields
920 which might result in the use of inner headers if an
921 encapsulation protocol is used. For example this will
922 improve the performance for tunnel users because the
923 packets will be distributed according to the encapsulated
924 flows.
925
926 encap3+4
927
928 This policy uses the same formula as layer3+4 but it
929 relies on skb_flow_dissect to obtain the header fields
930 which might result in the use of inner headers if an
931 encapsulation protocol is used. For example this will
932 improve the performance for tunnel users because the
933 packets will be distributed according to the encapsulated
934 flows.
935
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700936 The default value is layer2. This option was added in bonding
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800937 version 2.6.3. In earlier versions of bonding, this parameter
938 does not exist, and the layer2 policy is the only policy. The
939 layer2+3 value was added for bonding version 3.2.2.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700940
Flavio Leitnerc2952c32010-10-05 14:23:59 +0000941resend_igmp
942
943 Specifies the number of IGMP membership reports to be issued after
944 a failover event. One membership report is issued immediately after
945 the failover, subsequent packets are sent in each 200ms interval.
946
Flavio Leitner94265cf2011-05-25 08:38:58 +0000947 The valid range is 0 - 255; the default value is 1. A value of 0
948 prevents the IGMP membership report from being issued in response
949 to the failover event.
950
951 This option is useful for bonding modes balance-rr (0), active-backup
952 (1), balance-tlb (5) and balance-alb (6), in which a failover can
953 switch the IGMP traffic from one slave to another. Therefore a fresh
954 IGMP report must be issued to cause the switch to forward the incoming
955 IGMP traffic over the newly selected slave.
956
957 This option was added for bonding version 3.7.0.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958
dingtianhong84a6a0a2013-12-21 14:40:22 +0800959lp_interval
960
961 Specifies the number of seconds between instances where the bonding
962 driver sends learning packets to each slaves peer switch.
963
964 The valid range is 1 - 0x7fffffff; the default value is 1. This Option
965 has effect only in balance-tlb and balance-alb modes.
966
Linus Torvalds1da177e2005-04-16 15:20:36 -07009673. Configuring Bonding Devices
968==============================
969
Auke Kok6224e012006-06-08 11:15:35 -0700970 You can configure bonding using either your distro's network
Cong Wangb1098bb2013-05-27 15:49:16 +0000971initialization scripts, or manually using either iproute2 or the
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000972sysfs interface. Distros generally use one of three packages for the
973network initialization scripts: initscripts, sysconfig or interfaces.
974Recent versions of these packages have support for bonding, while older
Auke Kok6224e012006-06-08 11:15:35 -0700975versions do not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700976
977 We will first describe the options for configuring bonding for
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000978distros using versions of initscripts, sysconfig and interfaces with full
979or partial support for bonding, then provide information on enabling
Linus Torvalds1da177e2005-04-16 15:20:36 -0700980bonding without support from the network initialization scripts (i.e.,
981older versions of initscripts or sysconfig).
982
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000983 If you're unsure whether your distro uses sysconfig,
984initscripts or interfaces, or don't know if it's new enough, have no fear.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985Determining this is fairly straightforward.
986
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000987 First, look for a file called interfaces in /etc/network directory.
988If this file is present in your system, then your system use interfaces. See
989Configuration with Interfaces Support.
990
991 Else, issue the command:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700992
993$ rpm -qf /sbin/ifup
994
995 It will respond with a line of text starting with either
996"initscripts" or "sysconfig," followed by some numbers. This is the
997package that provides your network initialization scripts.
998
999 Next, to determine if your installation supports bonding,
1000issue the command:
1001
1002$ grep ifenslave /sbin/ifup
1003
1004 If this returns any matches, then your initscripts or
1005sysconfig has support for bonding.
1006
Auke Kok6224e012006-06-08 11:15:35 -070010073.1 Configuration with Sysconfig Support
Linus Torvalds1da177e2005-04-16 15:20:36 -07001008----------------------------------------
1009
1010 This section applies to distros using a version of sysconfig
1011with bonding support, for example, SuSE Linux Enterprise Server 9.
1012
1013 SuSE SLES 9's networking configuration system does support
1014bonding, however, at this writing, the YaST system configuration
Auke Kok6224e012006-06-08 11:15:35 -07001015front end does not provide any means to work with bonding devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001016Bonding devices can be managed by hand, however, as follows.
1017
1018 First, if they have not already been configured, configure the
1019slave devices. On SLES 9, this is most easily done by running the
1020yast2 sysconfig configuration utility. The goal is for to create an
1021ifcfg-id file for each slave device. The simplest way to accomplish
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001022this is to configure the devices for DHCP (this is only to get the
1023file ifcfg-id file created; see below for some issues with DHCP). The
1024name of the configuration file for each device will be of the form:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001025
1026ifcfg-id-xx:xx:xx:xx:xx:xx
1027
1028 Where the "xx" portion will be replaced with the digits from
1029the device's permanent MAC address.
1030
1031 Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been
1032created, it is necessary to edit the configuration files for the slave
1033devices (the MAC addresses correspond to those of the slave devices).
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001034Before editing, the file will contain multiple lines, and will look
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035something like this:
1036
1037BOOTPROTO='dhcp'
1038STARTMODE='on'
1039USERCTL='no'
1040UNIQUE='XNzu.WeZGOGF+4wE'
1041_nm_name='bus-pci-0001:61:01.0'
1042
1043 Change the BOOTPROTO and STARTMODE lines to the following:
1044
1045BOOTPROTO='none'
1046STARTMODE='off'
1047
1048 Do not alter the UNIQUE or _nm_name lines. Remove any other
1049lines (USERCTL, etc).
1050
1051 Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified,
1052it's time to create the configuration file for the bonding device
1053itself. This file is named ifcfg-bondX, where X is the number of the
1054bonding device to create, starting at 0. The first such file is
1055ifcfg-bond0, the second is ifcfg-bond1, and so on. The sysconfig
1056network configuration system will correctly start multiple instances
1057of bonding.
1058
1059 The contents of the ifcfg-bondX file is as follows:
1060
1061BOOTPROTO="static"
1062BROADCAST="10.0.2.255"
1063IPADDR="10.0.2.10"
1064NETMASK="255.255.0.0"
1065NETWORK="10.0.2.0"
1066REMOTE_IPADDR=""
1067STARTMODE="onboot"
1068BONDING_MASTER="yes"
1069BONDING_MODULE_OPTS="mode=active-backup miimon=100"
1070BONDING_SLAVE0="eth0"
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001071BONDING_SLAVE1="bus-pci-0000:06:08.1"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001072
1073 Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK
1074values with the appropriate values for your network.
1075
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 The STARTMODE specifies when the device is brought online.
1077The possible values are:
1078
1079 onboot: The device is started at boot time. If you're not
1080 sure, this is probably what you want.
1081
1082 manual: The device is started only when ifup is called
1083 manually. Bonding devices may be configured this
1084 way if you do not wish them to start automatically
1085 at boot for some reason.
1086
1087 hotplug: The device is started by a hotplug event. This is not
1088 a valid choice for a bonding device.
1089
1090 off or ignore: The device configuration is ignored.
1091
1092 The line BONDING_MASTER='yes' indicates that the device is a
1093bonding master device. The only useful value is "yes."
1094
1095 The contents of BONDING_MODULE_OPTS are supplied to the
1096instance of the bonding module for this device. Specify the options
1097for the bonding mode, link monitoring, and so on here. Do not include
1098the max_bonds bonding parameter; this will confuse the configuration
1099system if you have multiple bonding devices.
1100
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001101 Finally, supply one BONDING_SLAVEn="slave device" for each
1102slave. where "n" is an increasing value, one for each slave. The
1103"slave device" is either an interface name, e.g., "eth0", or a device
1104specifier for the network device. The interface name is easier to
1105find, but the ethN names are subject to change at boot time if, e.g.,
1106a device early in the sequence has failed. The device specifiers
1107(bus-pci-0000:06:08.1 in the example above) specify the physical
1108network device, and will not change unless the device's bus location
1109changes (for example, it is moved from one PCI slot to another). The
1110example above uses one of each type for demonstration purposes; most
1111configurations will choose one or the other for all slave devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001112
1113 When all configuration files have been modified or created,
1114networking must be restarted for the configuration changes to take
1115effect. This can be accomplished via the following:
1116
1117# /etc/init.d/network restart
1118
1119 Note that the network control script (/sbin/ifdown) will
1120remove the bonding module as part of the network shutdown processing,
1121so it is not necessary to remove the module by hand if, e.g., the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001122module parameters have changed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001123
1124 Also, at this writing, YaST/YaST2 will not manage bonding
1125devices (they do not show bonding interfaces on its list of network
1126devices). It is necessary to edit the configuration file by hand to
1127change the bonding configuration.
1128
1129 Additional general options and details of the ifcfg file
1130format can be found in an example ifcfg template file:
1131
1132/etc/sysconfig/network/ifcfg.template
1133
1134 Note that the template does not document the various BONDING_
1135settings described above, but does describe many of the other options.
1136
Auke Kok6224e012006-06-08 11:15:35 -070011373.1.1 Using DHCP with Sysconfig
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001138-------------------------------
1139
1140 Under sysconfig, configuring a device with BOOTPROTO='dhcp'
1141will cause it to query DHCP for its IP address information. At this
1142writing, this does not function for bonding devices; the scripts
1143attempt to obtain the device address from DHCP prior to adding any of
1144the slave devices. Without active slaves, the DHCP requests are not
1145sent to the network.
1146
Auke Kok6224e012006-06-08 11:15:35 -070011473.1.2 Configuring Multiple Bonds with Sysconfig
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001148-----------------------------------------------
1149
1150 The sysconfig network initialization system is capable of
1151handling multiple bonding devices. All that is necessary is for each
1152bonding instance to have an appropriately configured ifcfg-bondX file
1153(as described above). Do not specify the "max_bonds" parameter to any
1154instance of bonding, as this will confuse sysconfig. If you require
1155multiple bonding devices with identical parameters, create multiple
1156ifcfg-bondX files.
1157
1158 Because the sysconfig scripts supply the bonding module
1159options in the ifcfg-bondX file, it is not necessary to add them to
Lucas De Marchi970e2482012-03-30 13:37:16 -07001160the system /etc/modules.d/*.conf configuration files.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001161
Auke Kok6224e012006-06-08 11:15:35 -070011623.2 Configuration with Initscripts Support
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163------------------------------------------
1164
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001165 This section applies to distros using a recent version of
1166initscripts with bonding support, for example, Red Hat Enterprise Linux
1167version 3 or later, Fedora, etc. On these systems, the network
1168initialization scripts have knowledge of bonding, and can be configured to
1169control bonding devices. Note that older versions of the initscripts
1170package have lower levels of support for bonding; this will be noted where
1171applicable.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001172
1173 These distros will not automatically load the network adapter
1174driver unless the ethX device is configured with an IP address.
1175Because of this constraint, users must manually configure a
1176network-script file for all physical adapters that will be members of
1177a bondX link. Network script files are located in the directory:
1178
1179/etc/sysconfig/network-scripts
1180
1181 The file name must be prefixed with "ifcfg-eth" and suffixed
1182with the adapter's physical adapter number. For example, the script
1183for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0.
1184Place the following text in the file:
1185
1186DEVICE=eth0
1187USERCTL=no
1188ONBOOT=yes
1189MASTER=bond0
1190SLAVE=yes
1191BOOTPROTO=none
1192
1193 The DEVICE= line will be different for every ethX device and
1194must correspond with the name of the file, i.e., ifcfg-eth1 must have
1195a device line of DEVICE=eth1. The setting of the MASTER= line will
1196also depend on the final bonding interface name chosen for your bond.
1197As with other network devices, these typically start at 0, and go up
1198one for each device, i.e., the first bonding instance is bond0, the
1199second is bond1, and so on.
1200
1201 Next, create a bond network script. The file name for this
1202script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is
1203the number of the bond. For bond0 the file is named "ifcfg-bond0",
1204for bond1 it is named "ifcfg-bond1", and so on. Within that file,
1205place the following text:
1206
1207DEVICE=bond0
1208IPADDR=192.168.1.1
1209NETMASK=255.255.255.0
1210NETWORK=192.168.1.0
1211BROADCAST=192.168.1.255
1212ONBOOT=yes
1213BOOTPROTO=none
1214USERCTL=no
1215
1216 Be sure to change the networking specific lines (IPADDR,
1217NETMASK, NETWORK and BROADCAST) to match your network configuration.
1218
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001219 For later versions of initscripts, such as that found with Fedora
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +000012207 (or later) and Red Hat Enterprise Linux version 5 (or later), it is possible,
1221and, indeed, preferable, to specify the bonding options in the ifcfg-bond0
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001222file, e.g. a line of the format:
1223
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001224BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=192.168.1.254"
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001225
1226 will configure the bond with the specified options. The options
1227specified in BONDING_OPTS are identical to the bonding module parameters
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001228except for the arp_ip_target field when using versions of initscripts older
1229than and 8.57 (Fedora 8) and 8.45.19 (Red Hat Enterprise Linux 5.2). When
1230using older versions each target should be included as a separate option and
1231should be preceded by a '+' to indicate it should be added to the list of
1232queried targets, e.g.,
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001233
1234 arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2
1235
1236 is the proper syntax to specify multiple targets. When specifying
Lucas De Marchi970e2482012-03-30 13:37:16 -07001237options via BONDING_OPTS, it is not necessary to edit /etc/modprobe.d/*.conf.
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001238
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001239 For even older versions of initscripts that do not support
Lucas De Marchi970e2482012-03-30 13:37:16 -07001240BONDING_OPTS, it is necessary to edit /etc/modprobe.d/*.conf, depending upon
1241your distro) to load the bonding module with your desired options when the
1242bond0 interface is brought up. The following lines in /etc/modprobe.d/*.conf
1243will load the bonding module, and select its options:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001244
1245alias bond0 bonding
1246options bond0 mode=balance-alb miimon=100
1247
1248 Replace the sample parameters with the appropriate set of
1249options for your configuration.
1250
1251 Finally run "/etc/rc.d/init.d/network restart" as root. This
1252will restart the networking subsystem and your bond link should be now
1253up and running.
1254
Auke Kok6224e012006-06-08 11:15:35 -070012553.2.1 Using DHCP with Initscripts
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001256---------------------------------
1257
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001258 Recent versions of initscripts (the versions supplied with Fedora
1259Core 3 and Red Hat Enterprise Linux 4, or later versions, are reported to
1260work) have support for assigning IP information to bonding devices via
1261DHCP.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001262
1263 To configure bonding for DHCP, configure it as described
1264above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp"
1265and add a line consisting of "TYPE=Bonding". Note that the TYPE value
1266is case sensitive.
1267
Auke Kok6224e012006-06-08 11:15:35 -070012683.2.2 Configuring Multiple Bonds with Initscripts
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001269-------------------------------------------------
1270
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001271 Initscripts packages that are included with Fedora 7 and Red Hat
1272Enterprise Linux 5 support multiple bonding interfaces by simply
1273specifying the appropriate BONDING_OPTS= in ifcfg-bondX where X is the
1274number of the bond. This support requires sysfs support in the kernel,
1275and a bonding driver of version 3.0.0 or later. Other configurations may
1276not support this method for specifying multiple bonding interfaces; for
1277those instances, see the "Configuring Multiple Bonds Manually" section,
1278below.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001279
Cong Wangb1098bb2013-05-27 15:49:16 +000012803.3 Configuring Bonding Manually with iproute2
Auke Kok6224e012006-06-08 11:15:35 -07001281-----------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282
1283 This section applies to distros whose network initialization
1284scripts (the sysconfig or initscripts package) do not have specific
1285knowledge of bonding. One such distro is SuSE Linux Enterprise Server
1286version 8.
1287
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001288 The general method for these systems is to place the bonding
Lucas De Marchi970e2482012-03-30 13:37:16 -07001289module parameters into a config file in /etc/modprobe.d/ (as
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001290appropriate for the installed distro), then add modprobe and/or
Cong Wangb1098bb2013-05-27 15:49:16 +00001291`ip link` commands to the system's global init script. The name of
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001292the global init script differs; for sysconfig, it is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001293/etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local.
1294
1295 For example, if you wanted to make a simple bond of two e100
1296devices (presumed to be eth0 and eth1), and have it persist across
1297reboots, edit the appropriate file (/etc/init.d/boot.local or
1298/etc/rc.d/rc.local), and add the following:
1299
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001300modprobe bonding mode=balance-alb miimon=100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001301modprobe e100
1302ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
Cong Wangb1098bb2013-05-27 15:49:16 +00001303ip link set eth0 master bond0
1304ip link set eth1 master bond0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001305
1306 Replace the example bonding module parameters and bond0
1307network configuration (IP address, netmask, etc) with the appropriate
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001308values for your configuration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309
1310 Unfortunately, this method will not provide support for the
1311ifup and ifdown scripts on the bond devices. To reload the bonding
1312configuration, it is necessary to run the initialization script, e.g.,
1313
1314# /etc/init.d/boot.local
1315
1316 or
1317
1318# /etc/rc.d/rc.local
1319
1320 It may be desirable in such a case to create a separate script
1321which only initializes the bonding configuration, then call that
1322separate script from within boot.local. This allows for bonding to be
1323enabled without re-running the entire global init script.
1324
1325 To shut down the bonding devices, it is necessary to first
1326mark the bonding device itself as being down, then remove the
1327appropriate device driver modules. For our example above, you can do
1328the following:
1329
1330# ifconfig bond0 down
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001331# rmmod bonding
Linus Torvalds1da177e2005-04-16 15:20:36 -07001332# rmmod e100
1333
1334 Again, for convenience, it may be desirable to create a script
1335with these commands.
1336
1337
Jay Vosburgh00354cf2005-07-21 12:18:02 -070013383.3.1 Configuring Multiple Bonds Manually
1339-----------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340
1341 This section contains information on configuring multiple
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001342bonding devices with differing options for those systems whose network
1343initialization scripts lack support for configuring multiple bonds.
1344
1345 If you require multiple bonding devices, but all with the same
1346options, you may wish to use the "max_bonds" module parameter,
1347documented above.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001348
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001349 To create multiple bonding devices with differing options, it is
Rick Jonesf8b72d32012-07-20 10:51:37 +00001350preferable to use bonding parameters exported by sysfs, documented in the
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001351section below.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001353 For versions of bonding without sysfs support, the only means to
1354provide multiple instances of bonding with differing options is to load
1355the bonding driver multiple times. Note that current versions of the
1356sysconfig network initialization scripts handle this automatically; if
1357your distro uses these scripts, no special action is needed. See the
1358section Configuring Bonding Devices, above, if you're not sure about your
1359network initialization scripts.
1360
1361 To load multiple instances of the module, it is necessary to
1362specify a different name for each instance (the module loading system
1363requires that every loaded module, even multiple instances of the same
1364module, have a unique name). This is accomplished by supplying multiple
Lucas De Marchi970e2482012-03-30 13:37:16 -07001365sets of bonding options in /etc/modprobe.d/*.conf, for example:
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001366
1367alias bond0 bonding
1368options bond0 -o bond0 mode=balance-rr miimon=100
1369
1370alias bond1 bonding
1371options bond1 -o bond1 mode=balance-alb miimon=50
1372
1373 will load the bonding module two times. The first instance is
1374named "bond0" and creates the bond0 device in balance-rr mode with an
1375miimon of 100. The second instance is named "bond1" and creates the
1376bond1 device in balance-alb mode with an miimon of 50.
1377
1378 In some circumstances (typically with older distributions),
1379the above does not work, and the second bonding instance never sees
1380its options. In that case, the second options line can be substituted
1381as follows:
1382
1383install bond1 /sbin/modprobe --ignore-install bonding -o bond1 \
1384 mode=balance-alb miimon=50
1385
1386 This may be repeated any number of times, specifying a new and
1387unique name in place of bond1 for each subsequent instance.
1388
1389 It has been observed that some Red Hat supplied kernels are unable
1390to rename modules at load time (the "-o bond1" part). Attempts to pass
1391that option to modprobe will produce an "Operation not permitted" error.
1392This has been reported on some Fedora Core kernels, and has been seen on
1393RHEL 4 as well. On kernels exhibiting this problem, it will be impossible
1394to configure multiple bonds with differing parameters (as they are older
1395kernels, and also lack sysfs support).
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001396
Auke Kok6224e012006-06-08 11:15:35 -070013973.4 Configuring Bonding Manually via Sysfs
1398------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001400 Starting with version 3.0.0, Channel Bonding may be configured
Auke Kok6224e012006-06-08 11:15:35 -07001401via the sysfs interface. This interface allows dynamic configuration
1402of all bonds in the system without unloading the module. It also
1403allows for adding and removing bonds at runtime. Ifenslave is no
1404longer required, though it is still supported.
1405
1406 Use of the sysfs interface allows you to use multiple bonds
1407with different configurations without having to reload the module.
1408It also allows you to use multiple, differently configured bonds when
1409bonding is compiled into the kernel.
1410
1411 You must have the sysfs filesystem mounted to configure
1412bonding this way. The examples in this document assume that you
1413are using the standard mount point for sysfs, e.g. /sys. If your
1414sysfs filesystem is mounted elsewhere, you will need to adjust the
1415example paths accordingly.
1416
1417Creating and Destroying Bonds
1418-----------------------------
1419To add a new bond foo:
1420# echo +foo > /sys/class/net/bonding_masters
1421
1422To remove an existing bond bar:
1423# echo -bar > /sys/class/net/bonding_masters
1424
1425To show all existing bonds:
1426# cat /sys/class/net/bonding_masters
1427
1428NOTE: due to 4K size limitation of sysfs files, this list may be
1429truncated if you have more than a few hundred bonds. This is unlikely
1430to occur under normal operating conditions.
1431
1432Adding and Removing Slaves
1433--------------------------
1434 Interfaces may be enslaved to a bond using the file
1435/sys/class/net/<bond>/bonding/slaves. The semantics for this file
1436are the same as for the bonding_masters file.
1437
1438To enslave interface eth0 to bond bond0:
1439# ifconfig bond0 up
1440# echo +eth0 > /sys/class/net/bond0/bonding/slaves
1441
1442To free slave eth0 from bond bond0:
1443# echo -eth0 > /sys/class/net/bond0/bonding/slaves
1444
Auke Kok6224e012006-06-08 11:15:35 -07001445 When an interface is enslaved to a bond, symlinks between the
1446two are created in the sysfs filesystem. In this case, you would get
1447/sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and
1448/sys/class/net/eth0/master pointing to /sys/class/net/bond0.
1449
1450 This means that you can tell quickly whether or not an
1451interface is enslaved by looking for the master symlink. Thus:
1452# echo -eth0 > /sys/class/net/eth0/master/bonding/slaves
1453will free eth0 from whatever bond it is enslaved to, regardless of
1454the name of the bond interface.
1455
1456Changing a Bond's Configuration
1457-------------------------------
1458 Each bond may be configured individually by manipulating the
1459files located in /sys/class/net/<bond name>/bonding
1460
1461 The names of these files correspond directly with the command-
Paolo Ornati670e9f32006-10-03 22:57:56 +02001462line parameters described elsewhere in this file, and, with the
Auke Kok6224e012006-06-08 11:15:35 -07001463exception of arp_ip_target, they accept the same values. To see the
1464current setting, simply cat the appropriate file.
1465
1466 A few examples will be given here; for specific usage
1467guidelines for each parameter, see the appropriate section in this
1468document.
1469
1470To configure bond0 for balance-alb mode:
1471# ifconfig bond0 down
1472# echo 6 > /sys/class/net/bond0/bonding/mode
1473 - or -
1474# echo balance-alb > /sys/class/net/bond0/bonding/mode
1475 NOTE: The bond interface must be down before the mode can be
1476changed.
1477
1478To enable MII monitoring on bond0 with a 1 second interval:
1479# echo 1000 > /sys/class/net/bond0/bonding/miimon
1480 NOTE: If ARP monitoring is enabled, it will disabled when MII
1481monitoring is enabled, and vice-versa.
1482
1483To add ARP targets:
1484# echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
1485# echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target
Brian Haley5a31bec2009-04-13 00:11:30 -07001486 NOTE: up to 16 target addresses may be specified.
Auke Kok6224e012006-06-08 11:15:35 -07001487
1488To remove an ARP target:
1489# echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
1490
Neil Horman7eacd032013-09-13 11:05:33 -04001491To configure the interval between learning packet transmits:
1492# echo 12 > /sys/class/net/bond0/bonding/lp_interval
1493 NOTE: the lp_inteval is the number of seconds between instances where
1494the bonding driver sends learning packets to each slaves peer switch. The
1495default interval is 1 second.
1496
Auke Kok6224e012006-06-08 11:15:35 -07001497Example Configuration
1498---------------------
1499 We begin with the same example that is shown in section 3.3,
1500executed with sysfs, and without using ifenslave.
1501
1502 To make a simple bond of two e100 devices (presumed to be eth0
1503and eth1), and have it persist across reboots, edit the appropriate
1504file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the
1505following:
1506
1507modprobe bonding
1508modprobe e100
1509echo balance-alb > /sys/class/net/bond0/bonding/mode
1510ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
1511echo 100 > /sys/class/net/bond0/bonding/miimon
1512echo +eth0 > /sys/class/net/bond0/bonding/slaves
1513echo +eth1 > /sys/class/net/bond0/bonding/slaves
1514
1515 To add a second bond, with two e1000 interfaces in
1516active-backup mode, using ARP monitoring, add the following lines to
1517your init script:
1518
1519modprobe e1000
1520echo +bond1 > /sys/class/net/bonding_masters
1521echo active-backup > /sys/class/net/bond1/bonding/mode
1522ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up
1523echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target
1524echo 2000 > /sys/class/net/bond1/bonding/arp_interval
1525echo +eth2 > /sys/class/net/bond1/bonding/slaves
1526echo +eth3 > /sys/class/net/bond1/bonding/slaves
1527
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +000015283.5 Configuration with Interfaces Support
1529-----------------------------------------
1530
1531 This section applies to distros which use /etc/network/interfaces file
1532to describe network interface configuration, most notably Debian and it's
1533derivatives.
1534
1535 The ifup and ifdown commands on Debian don't support bonding out of
1536the box. The ifenslave-2.6 package should be installed to provide bonding
1537support. Once installed, this package will provide bond-* options to be used
1538into /etc/network/interfaces.
1539
1540 Note that ifenslave-2.6 package will load the bonding module and use
1541the ifenslave command when appropriate.
1542
1543Example Configurations
1544----------------------
1545
1546In /etc/network/interfaces, the following stanza will configure bond0, in
1547active-backup mode, with eth0 and eth1 as slaves.
1548
1549auto bond0
1550iface bond0 inet dhcp
1551 bond-slaves eth0 eth1
1552 bond-mode active-backup
1553 bond-miimon 100
1554 bond-primary eth0 eth1
1555
1556If the above configuration doesn't work, you might have a system using
1557upstart for system startup. This is most notably true for recent
1558Ubuntu versions. The following stanza in /etc/network/interfaces will
1559produce the same result on those systems.
1560
1561auto bond0
1562iface bond0 inet dhcp
1563 bond-slaves none
1564 bond-mode active-backup
1565 bond-miimon 100
1566
1567auto eth0
1568iface eth0 inet manual
1569 bond-master bond0
1570 bond-primary eth0 eth1
1571
1572auto eth1
1573iface eth1 inet manual
1574 bond-master bond0
1575 bond-primary eth0 eth1
1576
1577For a full list of bond-* supported options in /etc/network/interfaces and some
1578more advanced examples tailored to you particular distros, see the files in
1579/usr/share/doc/ifenslave-2.6.
1580
15813.6 Overriding Configuration for Special Cases
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001582----------------------------------------------
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +00001583
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001584When using the bonding driver, the physical port which transmits a frame is
1585typically selected by the bonding driver, and is not relevant to the user or
1586system administrator. The output port is simply selected using the policies of
1587the selected bonding mode. On occasion however, it is helpful to direct certain
1588classes of traffic to certain physical interfaces on output to implement
1589slightly more complex policies. For example, to reach a web server over a
1590bonded interface in which eth0 connects to a private network, while eth1
1591connects via a public network, it may be desirous to bias the bond to send said
1592traffic over eth0 first, using eth1 only as a fall back, while all other traffic
1593can safely be sent over either interface. Such configurations may be achieved
1594using the traffic control utilities inherent in linux.
Auke Kok6224e012006-06-08 11:15:35 -07001595
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001596By default the bonding driver is multiqueue aware and 16 queues are created
1597when the driver initializes (see Documentation/networking/multiqueue.txt
1598for details). If more or less queues are desired the module parameter
1599tx_queues can be used to change this value. There is no sysfs parameter
1600available as the allocation is done at module init time.
1601
1602The output of the file /proc/net/bonding/bondX has changed so the output Queue
1603ID is now printed for each slave:
1604
1605Bonding Mode: fault-tolerance (active-backup)
1606Primary Slave: None
1607Currently Active Slave: eth0
1608MII Status: up
1609MII Polling Interval (ms): 0
1610Up Delay (ms): 0
1611Down Delay (ms): 0
1612
1613Slave Interface: eth0
1614MII Status: up
1615Link Failure Count: 0
1616Permanent HW addr: 00:1a:a0:12:8f:cb
1617Slave queue ID: 0
1618
1619Slave Interface: eth1
1620MII Status: up
1621Link Failure Count: 0
1622Permanent HW addr: 00:1a:a0:12:8f:cc
1623Slave queue ID: 2
1624
1625The queue_id for a slave can be set using the command:
1626
1627# echo "eth1:2" > /sys/class/net/bond0/bonding/queue_id
1628
1629Any interface that needs a queue_id set should set it with multiple calls
1630like the one above until proper priorities are set for all interfaces. On
1631distributions that allow configuration via initscripts, multiple 'queue_id'
1632arguments can be added to BONDING_OPTS to set all needed slave queues.
1633
1634These queue id's can be used in conjunction with the tc utility to configure
1635a multiqueue qdisc and filters to bias certain traffic to transmit on certain
1636slave devices. For instance, say we wanted, in the above configuration to
1637force all traffic bound to 192.168.1.100 to use eth1 in the bond as its output
1638device. The following commands would accomplish this:
1639
1640# tc qdisc add dev bond0 handle 1 root multiq
1641
1642# tc filter add dev bond0 protocol ip parent 1: prio 1 u32 match ip dst \
1643 192.168.1.100 action skbedit queue_mapping 2
1644
1645These commands tell the kernel to attach a multiqueue queue discipline to the
1646bond0 interface and filter traffic enqueued to it, such that packets with a dst
1647ip of 192.168.1.100 have their output queue mapping value overwritten to 2.
1648This value is then passed into the driver, causing the normal output path
1649selection policy to be overridden, selecting instead qid 2, which maps to eth1.
1650
1651Note that qid values begin at 1. Qid 0 is reserved to initiate to the driver
1652that normal output policy selection should take place. One benefit to simply
1653leaving the qid for a slave to 0 is the multiqueue awareness in the bonding
1654driver that is now present. This awareness allows tc filters to be placed on
1655slave devices as well as bond devices and the bonding driver will simply act as
1656a pass-through for selecting output queues on the slave device rather than
1657output port selection.
1658
1659This feature first appeared in bonding driver version 3.7.0 and support for
1660output slave selection was limited to round-robin and active-backup modes.
1661
Mahesh Bandeward22a5fc2015-05-09 00:01:57 -070016623.7 Configuring LACP for 802.3ad mode in a more secure way
1663----------------------------------------------------------
1664
1665When using 802.3ad bonding mode, the Actor (host) and Partner (switch)
1666exchange LACPDUs. These LACPDUs cannot be sniffed, because they are
1667destined to link local mac addresses (which switches/bridges are not
1668supposed to forward). However, most of the values are easily predictable
1669or are simply the machine's MAC address (which is trivially known to all
1670other hosts in the same L2). This implies that other machines in the L2
1671domain can spoof LACPDU packets from other hosts to the switch and potentially
1672cause mayhem by joining (from the point of view of the switch) another
1673machine's aggregate, thus receiving a portion of that hosts incoming
1674traffic and / or spoofing traffic from that machine themselves (potentially
1675even successfully terminating some portion of flows). Though this is not
1676a likely scenario, one could avoid this possibility by simply configuring
1677few bonding parameters:
1678
1679 (a) ad_actor_system : You can set a random mac-address that can be used for
1680 these LACPDU exchanges. The value can not be either NULL or Multicast.
1681 Also it's preferable to set the local-admin bit. Following shell code
1682 generates a random mac-address as described above.
1683
1684 # sys_mac_addr=$(printf '%02x:%02x:%02x:%02x:%02x:%02x' \
1685 $(( (RANDOM & 0xFE) | 0x02 )) \
1686 $(( RANDOM & 0xFF )) \
1687 $(( RANDOM & 0xFF )) \
1688 $(( RANDOM & 0xFF )) \
1689 $(( RANDOM & 0xFF )) \
1690 $(( RANDOM & 0xFF )))
1691 # echo $sys_mac_addr > /sys/class/net/bond0/bonding/ad_actor_system
1692
1693 (b) ad_actor_sys_prio : Randomize the system priority. The default value
1694 is 65535, but system can take the value from 1 - 65535. Following shell
1695 code generates random priority and sets it.
1696
1697 # sys_prio=$(( 1 + RANDOM + RANDOM ))
1698 # echo $sys_prio > /sys/class/net/bond0/bonding/ad_actor_sys_prio
1699
1700 (c) ad_user_port_key : Use the user portion of the port-key. The default
1701 keeps this empty. These are the upper 10 bits of the port-key and value
1702 ranges from 0 - 1023. Following shell code generates these 10 bits and
1703 sets it.
1704
1705 # usr_port_key=$(( RANDOM & 0x3FF ))
1706 # echo $usr_port_key > /sys/class/net/bond0/bonding/ad_user_port_key
1707
1708
Andy Gospodarekbb1d9122010-06-02 08:40:18 +000017094 Querying Bonding Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001710=================================
1711
Auke Kok6224e012006-06-08 11:15:35 -070017124.1 Bonding Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001713-------------------------
1714
1715 Each bonding device has a read-only file residing in the
1716/proc/net/bonding directory. The file contents include information
1717about the bonding configuration, options and state of each slave.
1718
1719 For example, the contents of /proc/net/bonding/bond0 after the
1720driver is loaded with parameters of mode=0 and miimon=1000 is
1721generally as follows:
1722
1723 Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004)
1724 Bonding Mode: load balancing (round-robin)
1725 Currently Active Slave: eth0
1726 MII Status: up
1727 MII Polling Interval (ms): 1000
1728 Up Delay (ms): 0
1729 Down Delay (ms): 0
1730
1731 Slave Interface: eth1
1732 MII Status: up
1733 Link Failure Count: 1
1734
1735 Slave Interface: eth0
1736 MII Status: up
1737 Link Failure Count: 1
1738
1739 The precise format and contents will change depending upon the
1740bonding configuration, state, and version of the bonding driver.
1741
Auke Kok6224e012006-06-08 11:15:35 -070017424.2 Network configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001743-------------------------
1744
1745 The network configuration can be inspected using the ifconfig
1746command. Bonding devices will have the MASTER flag set; Bonding slave
1747devices will have the SLAVE flag set. The ifconfig output does not
1748contain information on which slaves are associated with which masters.
1749
1750 In the example below, the bond0 interface is the master
1751(MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of
1752bond0 have the same MAC address (HWaddr) as bond0 for all modes except
1753TLB and ALB that require a unique MAC address for each slave.
1754
1755# /sbin/ifconfig
1756bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
1757 inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0
1758 UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
1759 RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0
1760 TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0
1761 collisions:0 txqueuelen:0
1762
1763eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
Linus Torvalds1da177e2005-04-16 15:20:36 -07001764 UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
1765 RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0
1766 TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0
1767 collisions:0 txqueuelen:100
1768 Interrupt:10 Base address:0x1080
1769
1770eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
Linus Torvalds1da177e2005-04-16 15:20:36 -07001771 UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
1772 RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0
1773 TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0
1774 collisions:0 txqueuelen:100
1775 Interrupt:9 Base address:0x1400
1776
Auke Kok6224e012006-06-08 11:15:35 -070017775. Switch Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778=======================
1779
1780 For this section, "switch" refers to whatever system the
1781bonded devices are directly connected to (i.e., where the other end of
1782the cable plugs into). This may be an actual dedicated switch device,
1783or it may be another regular system (e.g., another computer running
1784Linux),
1785
1786 The active-backup, balance-tlb and balance-alb modes do not
1787require any specific configuration of the switch.
1788
1789 The 802.3ad mode requires that the switch have the appropriate
1790ports configured as an 802.3ad aggregation. The precise method used
1791to configure this varies from switch to switch, but, for example, a
1792Cisco 3550 series switch requires that the appropriate ports first be
1793grouped together in a single etherchannel instance, then that
1794etherchannel is set to mode "lacp" to enable 802.3ad (instead of
1795standard EtherChannel).
1796
1797 The balance-rr, balance-xor and broadcast modes generally
1798require that the switch have the appropriate ports grouped together.
1799The nomenclature for such a group differs between switches, it may be
1800called an "etherchannel" (as in the Cisco example, above), a "trunk
1801group" or some other similar variation. For these modes, each switch
1802will also have its own configuration options for the switch's transmit
1803policy to the bond. Typical choices include XOR of either the MAC or
1804IP addresses. The transmit policy of the two peers does not need to
1805match. For these three modes, the bonding mode really selects a
1806transmit policy for an EtherChannel group; all three will interoperate
1807with another EtherChannel group.
1808
1809
Auke Kok6224e012006-06-08 11:15:35 -070018106. 802.1q VLAN Support
Linus Torvalds1da177e2005-04-16 15:20:36 -07001811======================
1812
1813 It is possible to configure VLAN devices over a bond interface
1814using the 8021q driver. However, only packets coming from the 8021q
1815driver and passing through bonding will be tagged by default. Self
1816generated packets, for example, bonding's learning packets or ARP
1817packets generated by either ALB mode or the ARP monitor mechanism, are
1818tagged internally by bonding itself. As a result, bonding must
1819"learn" the VLAN IDs configured above it, and use those IDs to tag
1820self generated packets.
1821
1822 For reasons of simplicity, and to support the use of adapters
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001823that can do VLAN hardware acceleration offloading, the bonding
1824interface declares itself as fully hardware offloading capable, it gets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001825the add_vid/kill_vid notifications to gather the necessary
1826information, and it propagates those actions to the slaves. In case
1827of mixed adapter types, hardware accelerated tagged packets that
1828should go through an adapter that is not offloading capable are
1829"un-accelerated" by the bonding driver so the VLAN tag sits in the
1830regular location.
1831
1832 VLAN interfaces *must* be added on top of a bonding interface
1833only after enslaving at least one slave. The bonding interface has a
1834hardware address of 00:00:00:00:00:00 until the first slave is added.
1835If the VLAN interface is created prior to the first enslavement, it
1836would pick up the all-zeroes hardware address. Once the first slave
1837is attached to the bond, the bond device itself will pick up the
1838slave's hardware address, which is then available for the VLAN device.
1839
1840 Also, be aware that a similar problem can occur if all slaves
1841are released from a bond that still has one or more VLAN interfaces on
1842top of it. When a new slave is added, the bonding interface will
1843obtain its hardware address from the first slave, which might not
1844match the hardware address of the VLAN interfaces (which was
1845ultimately copied from an earlier slave).
1846
1847 There are two methods to insure that the VLAN device operates
1848with the correct hardware address if all slaves are removed from a
1849bond interface:
1850
1851 1. Remove all VLAN interfaces then recreate them
1852
1853 2. Set the bonding interface's hardware address so that it
1854matches the hardware address of the VLAN interfaces.
1855
1856 Note that changing a VLAN interface's HW address would set the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001857underlying device -- i.e. the bonding interface -- to promiscuous
Linus Torvalds1da177e2005-04-16 15:20:36 -07001858mode, which might not be what you want.
1859
1860
Auke Kok6224e012006-06-08 11:15:35 -070018617. Link Monitoring
Linus Torvalds1da177e2005-04-16 15:20:36 -07001862==================
1863
1864 The bonding driver at present supports two schemes for
1865monitoring a slave device's link state: the ARP monitor and the MII
1866monitor.
1867
1868 At the present time, due to implementation restrictions in the
1869bonding driver itself, it is not possible to enable both ARP and MII
1870monitoring simultaneously.
1871
Auke Kok6224e012006-06-08 11:15:35 -070018727.1 ARP Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -07001873-------------------------
1874
1875 The ARP monitor operates as its name suggests: it sends ARP
1876queries to one or more designated peer systems on the network, and
1877uses the response as an indication that the link is operating. This
1878gives some assurance that traffic is actually flowing to and from one
1879or more peers on the local network.
1880
1881 The ARP monitor relies on the device driver itself to verify
1882that traffic is flowing. In particular, the driver must keep up to
Florian Westphal5c2a9642016-05-04 22:51:47 +02001883date the last receive time, dev->last_rx. Drivers that use NETIF_F_LLTX
1884flag must also update netdev_queue->trans_start. If they do not, then the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001885ARP monitor will immediately fail any slaves using that driver, and
1886those slaves will stay down. If networking monitoring (tcpdump, etc)
1887shows the ARP requests and replies on the network, then it may be that
1888your device driver is not updating last_rx and trans_start.
1889
Auke Kok6224e012006-06-08 11:15:35 -070018907.2 Configuring Multiple ARP Targets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001891------------------------------------
1892
1893 While ARP monitoring can be done with just one target, it can
1894be useful in a High Availability setup to have several targets to
1895monitor. In the case of just one target, the target itself may go
1896down or have a problem making it unresponsive to ARP requests. Having
1897an additional target (or several) increases the reliability of the ARP
1898monitoring.
1899
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001900 Multiple ARP targets must be separated by commas as follows:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901
1902# example options for ARP monitoring with three targets
1903alias bond0 bonding
1904options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9
1905
1906 For just a single target the options would resemble:
1907
1908# example options for ARP monitoring with one target
1909alias bond0 bonding
1910options bond0 arp_interval=60 arp_ip_target=192.168.0.100
1911
1912
Auke Kok6224e012006-06-08 11:15:35 -070019137.3 MII Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -07001914-------------------------
1915
1916 The MII monitor monitors only the carrier state of the local
1917network interface. It accomplishes this in one of three ways: by
1918depending upon the device driver to maintain its carrier state, by
1919querying the device's MII registers, or by making an ethtool query to
1920the device.
1921
1922 If the use_carrier module parameter is 1 (the default value),
1923then the MII monitor will rely on the driver for carrier state
1924information (via the netif_carrier subsystem). As explained in the
1925use_carrier parameter information, above, if the MII monitor fails to
1926detect carrier loss on the device (e.g., when the cable is physically
1927disconnected), it may be that the driver does not support
1928netif_carrier.
1929
1930 If use_carrier is 0, then the MII monitor will first query the
1931device's (via ioctl) MII registers and check the link state. If that
1932request fails (not just that it returns carrier down), then the MII
1933monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain
1934the same information. If both methods fail (i.e., the driver either
1935does not support or had some error in processing both the MII register
1936and ethtool requests), then the MII monitor will assume the link is
1937up.
1938
Auke Kok6224e012006-06-08 11:15:35 -070019398. Potential Sources of Trouble
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940===============================
1941
Auke Kok6224e012006-06-08 11:15:35 -070019428.1 Adventures in Routing
Linus Torvalds1da177e2005-04-16 15:20:36 -07001943-------------------------
1944
1945 When bonding is configured, it is important that the slave
Auke Kok6224e012006-06-08 11:15:35 -07001946devices not have routes that supersede routes of the master (or,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947generally, not have routes at all). For example, suppose the bonding
1948device bond0 has two slaves, eth0 and eth1, and the routing table is
1949as follows:
1950
1951Kernel IP routing table
1952Destination Gateway Genmask Flags MSS Window irtt Iface
195310.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth0
195410.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth1
195510.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 bond0
1956127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo
1957
1958 This routing configuration will likely still update the
1959receive/transmit times in the driver (needed by the ARP monitor), but
1960may bypass the bonding driver (because outgoing traffic to, in this
1961case, another host on network 10 would use eth0 or eth1 before bond0).
1962
1963 The ARP monitor (and ARP itself) may become confused by this
1964configuration, because ARP requests (generated by the ARP monitor)
1965will be sent on one interface (bond0), but the corresponding reply
1966will arrive on a different interface (eth0). This reply looks to ARP
1967as an unsolicited ARP reply (because ARP matches replies on an
1968interface basis), and is discarded. The MII monitor is not affected
1969by the state of the routing table.
1970
1971 The solution here is simply to insure that slaves do not have
1972routes of their own, and if for some reason they must, those routes do
Auke Kok6224e012006-06-08 11:15:35 -07001973not supersede routes of their master. This should generally be the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001974case, but unusual configurations or errant manual or automatic static
1975route additions may cause trouble.
1976
Auke Kok6224e012006-06-08 11:15:35 -070019778.2 Ethernet Device Renaming
Linus Torvalds1da177e2005-04-16 15:20:36 -07001978----------------------------
1979
1980 On systems with network configuration scripts that do not
1981associate physical devices directly with network interface names (so
1982that the same physical device always has the same "ethX" name), it may
Lucas De Marchi970e2482012-03-30 13:37:16 -07001983be necessary to add some special logic to config files in
1984/etc/modprobe.d/.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001985
1986 For example, given a modules.conf containing the following:
1987
1988alias bond0 bonding
1989options bond0 mode=some-mode miimon=50
1990alias eth0 tg3
1991alias eth1 tg3
1992alias eth2 e1000
1993alias eth3 e1000
1994
1995 If neither eth0 and eth1 are slaves to bond0, then when the
1996bond0 interface comes up, the devices may end up reordered. This
1997happens because bonding is loaded first, then its slave device's
1998drivers are loaded next. Since no other drivers have been loaded,
1999when the e1000 driver loads, it will receive eth0 and eth1 for its
2000devices, but the bonding configuration tries to enslave eth2 and eth3
2001(which may later be assigned to the tg3 devices).
2002
2003 Adding the following:
2004
2005add above bonding e1000 tg3
2006
2007 causes modprobe to load e1000 then tg3, in that order, when
2008bonding is loaded. This command is fully documented in the
2009modules.conf manual page.
2010
Lucas De Marchi970e2482012-03-30 13:37:16 -07002011 On systems utilizing modprobe an equivalent problem can occur.
2012In this case, the following can be added to config files in
2013/etc/modprobe.d/ as:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002014
Lucas De Marchi78286cd2012-03-30 13:37:20 -07002015softdep bonding pre: tg3 e1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07002016
Lucas De Marchi970e2482012-03-30 13:37:16 -07002017 This will load tg3 and e1000 modules before loading the bonding one.
2018Full documentation on this can be found in the modprobe.d and modprobe
2019manual pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002020
Auke Kok6224e012006-06-08 11:15:35 -070020218.3. Painfully Slow Or No Failed Link Detection By Miimon
Linus Torvalds1da177e2005-04-16 15:20:36 -07002022---------------------------------------------------------
2023
2024 By default, bonding enables the use_carrier option, which
2025instructs bonding to trust the driver to maintain carrier state.
2026
2027 As discussed in the options section, above, some drivers do
2028not support the netif_carrier_on/_off link state tracking system.
2029With use_carrier enabled, bonding will always see these links as up,
2030regardless of their actual state.
2031
2032 Additionally, other drivers do support netif_carrier, but do
2033not maintain it in real time, e.g., only polling the link state at
2034some fixed interval. In this case, miimon will detect failures, but
2035only after some long period of time has expired. If it appears that
2036miimon is very slow in detecting link failures, try specifying
2037use_carrier=0 to see if that improves the failure detection time. If
2038it does, then it may be that the driver checks the carrier state at a
2039fixed interval, but does not cache the MII register values (so the
2040use_carrier=0 method of querying the registers directly works). If
2041use_carrier=0 does not improve the failover, then the driver may cache
2042the registers, or the problem may be elsewhere.
2043
2044 Also, remember that miimon only checks for the device's
2045carrier state. It has no way to determine the state of devices on or
2046beyond other ports of a switch, or if a switch is refusing to pass
2047traffic while still maintaining carrier on.
2048
Auke Kok6224e012006-06-08 11:15:35 -070020499. SNMP agents
Linus Torvalds1da177e2005-04-16 15:20:36 -07002050===============
2051
2052 If running SNMP agents, the bonding driver should be loaded
2053before any network drivers participating in a bond. This requirement
Tobias Klauserd533f672005-09-10 00:26:46 -07002054is due to the interface index (ipAdEntIfIndex) being associated to
Linus Torvalds1da177e2005-04-16 15:20:36 -07002055the first interface found with a given IP address. That is, there is
2056only one ipAdEntIfIndex for each IP address. For example, if eth0 and
2057eth1 are slaves of bond0 and the driver for eth0 is loaded before the
2058bonding driver, the interface for the IP address will be associated
2059with the eth0 interface. This configuration is shown below, the IP
2060address 192.168.1.1 has an interface index of 2 which indexes to eth0
2061in the ifDescr table (ifDescr.2).
2062
2063 interfaces.ifTable.ifEntry.ifDescr.1 = lo
2064 interfaces.ifTable.ifEntry.ifDescr.2 = eth0
2065 interfaces.ifTable.ifEntry.ifDescr.3 = eth1
2066 interfaces.ifTable.ifEntry.ifDescr.4 = eth2
2067 interfaces.ifTable.ifEntry.ifDescr.5 = eth3
2068 interfaces.ifTable.ifEntry.ifDescr.6 = bond0
2069 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5
2070 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
2071 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4
2072 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
2073
2074 This problem is avoided by loading the bonding driver before
2075any network drivers participating in a bond. Below is an example of
2076loading the bonding driver first, the IP address 192.168.1.1 is
2077correctly associated with ifDescr.2.
2078
2079 interfaces.ifTable.ifEntry.ifDescr.1 = lo
2080 interfaces.ifTable.ifEntry.ifDescr.2 = bond0
2081 interfaces.ifTable.ifEntry.ifDescr.3 = eth0
2082 interfaces.ifTable.ifEntry.ifDescr.4 = eth1
2083 interfaces.ifTable.ifEntry.ifDescr.5 = eth2
2084 interfaces.ifTable.ifEntry.ifDescr.6 = eth3
2085 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6
2086 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
2087 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5
2088 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
2089
2090 While some distributions may not report the interface name in
2091ifDescr, the association between the IP address and IfIndex remains
2092and SNMP functions such as Interface_Scan_Next will report that
2093association.
2094
Auke Kok6224e012006-06-08 11:15:35 -0700209510. Promiscuous mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096====================
2097
2098 When running network monitoring tools, e.g., tcpdump, it is
2099common to enable promiscuous mode on the device, so that all traffic
2100is seen (instead of seeing only traffic destined for the local host).
2101The bonding driver handles promiscuous mode changes to the bonding
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002102master device (e.g., bond0), and propagates the setting to the slave
Linus Torvalds1da177e2005-04-16 15:20:36 -07002103devices.
2104
2105 For the balance-rr, balance-xor, broadcast, and 802.3ad modes,
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002106the promiscuous mode setting is propagated to all slaves.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002107
2108 For the active-backup, balance-tlb and balance-alb modes, the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002109promiscuous mode setting is propagated only to the active slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002110
2111 For balance-tlb mode, the active slave is the slave currently
2112receiving inbound traffic.
2113
2114 For balance-alb mode, the active slave is the slave used as a
2115"primary." This slave is used for mode-specific control traffic, for
2116sending to peers that are unassigned or if the load is unbalanced.
2117
2118 For the active-backup, balance-tlb and balance-alb modes, when
2119the active slave changes (e.g., due to a link failure), the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002120promiscuous setting will be propagated to the new active slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002121
Auke Kok6224e012006-06-08 11:15:35 -0700212211. Configuring Bonding for High Availability
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002123=============================================
Linus Torvalds1da177e2005-04-16 15:20:36 -07002124
2125 High Availability refers to configurations that provide
2126maximum network availability by having redundant or backup devices,
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002127links or switches between the host and the rest of the world. The
2128goal is to provide the maximum availability of network connectivity
2129(i.e., the network always works), even though other configurations
2130could provide higher throughput.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002131
Auke Kok6224e012006-06-08 11:15:35 -0700213211.1 High Availability in a Single Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133--------------------------------------------------
2134
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002135 If two hosts (or a host and a single switch) are directly
2136connected via multiple physical links, then there is no availability
2137penalty to optimizing for maximum bandwidth. In this case, there is
2138only one switch (or peer), so if it fails, there is no alternative
2139access to fail over to. Additionally, the bonding load balance modes
2140support link monitoring of their members, so if individual links fail,
2141the load will be rebalanced across the remaining devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002142
Rick Jonesf8b72d32012-07-20 10:51:37 +00002143 See Section 12, "Configuring Bonding for Maximum Throughput"
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002144for information on configuring bonding with one peer device.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002145
Auke Kok6224e012006-06-08 11:15:35 -0700214611.2 High Availability in a Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -07002147----------------------------------------------------
2148
2149 With multiple switches, the configuration of bonding and the
2150network changes dramatically. In multiple switch topologies, there is
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002151a trade off between network availability and usable bandwidth.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002152
2153 Below is a sample network, configured to maximize the
2154availability of the network:
2155
2156 | |
2157 |port3 port3|
2158 +-----+----+ +-----+----+
2159 | |port2 ISL port2| |
2160 | switch A +--------------------------+ switch B |
2161 | | | |
2162 +-----+----+ +-----++---+
2163 |port1 port1|
2164 | +-------+ |
2165 +-------------+ host1 +---------------+
2166 eth0 +-------+ eth1
2167
2168 In this configuration, there is a link between the two
2169switches (ISL, or inter switch link), and multiple ports connecting to
2170the outside world ("port3" on each switch). There is no technical
2171reason that this could not be extended to a third switch.
2172
Auke Kok6224e012006-06-08 11:15:35 -0700217311.2.1 HA Bonding Mode Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002174-------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002175
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002176 In a topology such as the example above, the active-backup and
2177broadcast modes are the only useful bonding modes when optimizing for
2178availability; the other modes require all links to terminate on the
2179same peer for them to behave rationally.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002180
2181active-backup: This is generally the preferred mode, particularly if
2182 the switches have an ISL and play together well. If the
2183 network configuration is such that one switch is specifically
2184 a backup switch (e.g., has lower capacity, higher cost, etc),
2185 then the primary option can be used to insure that the
2186 preferred link is always used when it is available.
2187
2188broadcast: This mode is really a special purpose mode, and is suitable
2189 only for very specific needs. For example, if the two
2190 switches are not connected (no ISL), and the networks beyond
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002191 them are totally independent. In this case, if it is
Linus Torvalds1da177e2005-04-16 15:20:36 -07002192 necessary for some specific one-way traffic to reach both
2193 independent networks, then the broadcast mode may be suitable.
2194
Auke Kok6224e012006-06-08 11:15:35 -0700219511.2.2 HA Link Monitoring Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002196----------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002197
2198 The choice of link monitoring ultimately depends upon your
2199switch. If the switch can reliably fail ports in response to other
2200failures, then either the MII or ARP monitors should work. For
2201example, in the above example, if the "port3" link fails at the remote
2202end, the MII monitor has no direct means to detect this. The ARP
2203monitor could be configured with a target at the remote end of port3,
2204thus detecting that failure without switch support.
2205
2206 In general, however, in a multiple switch topology, the ARP
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002207monitor can provide a higher level of reliability in detecting end to
2208end connectivity failures (which may be caused by the failure of any
2209individual component to pass traffic for any reason). Additionally,
2210the ARP monitor should be configured with multiple targets (at least
2211one for each switch in the network). This will insure that,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002212regardless of which switch is active, the ARP monitor has a suitable
2213target to query.
2214
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002215 Note, also, that of late many switches now support a functionality
2216generally referred to as "trunk failover." This is a feature of the
2217switch that causes the link state of a particular switch port to be set
2218down (or up) when the state of another switch port goes down (or up).
Matt LaPlante19f59462009-04-27 15:06:31 +02002219Its purpose is to propagate link failures from logically "exterior" ports
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002220to the logically "interior" ports that bonding is able to monitor via
2221miimon. Availability and configuration for trunk failover varies by
2222switch, but this can be a viable alternative to the ARP monitor when using
2223suitable switches.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002224
Auke Kok6224e012006-06-08 11:15:35 -0700222512. Configuring Bonding for Maximum Throughput
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002226==============================================
Linus Torvalds1da177e2005-04-16 15:20:36 -07002227
Auke Kok6224e012006-06-08 11:15:35 -0700222812.1 Maximizing Throughput in a Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002229------------------------------------------------------
2230
2231 In a single switch configuration, the best method to maximize
2232throughput depends upon the application and network environment. The
2233various load balancing modes each have strengths and weaknesses in
2234different environments, as detailed below.
2235
2236 For this discussion, we will break down the topologies into
2237two categories. Depending upon the destination of most traffic, we
2238categorize them into either "gatewayed" or "local" configurations.
2239
2240 In a gatewayed configuration, the "switch" is acting primarily
2241as a router, and the majority of traffic passes through this router to
2242other networks. An example would be the following:
2243
2244
2245 +----------+ +----------+
2246 | |eth0 port1| | to other networks
2247 | Host A +---------------------+ router +------------------->
2248 | +---------------------+ | Hosts B and C are out
2249 | |eth1 port2| | here somewhere
2250 +----------+ +----------+
2251
2252 The router may be a dedicated router device, or another host
2253acting as a gateway. For our discussion, the important point is that
2254the majority of traffic from Host A will pass through the router to
2255some other network before reaching its final destination.
2256
2257 In a gatewayed network configuration, although Host A may
2258communicate with many other systems, all of its traffic will be sent
2259and received via one other peer on the local network, the router.
2260
2261 Note that the case of two systems connected directly via
2262multiple physical links is, for purposes of configuring bonding, the
2263same as a gatewayed configuration. In that case, it happens that all
2264traffic is destined for the "gateway" itself, not some other network
2265beyond the gateway.
2266
2267 In a local configuration, the "switch" is acting primarily as
2268a switch, and the majority of traffic passes through this switch to
2269reach other stations on the same network. An example would be the
2270following:
2271
2272 +----------+ +----------+ +--------+
2273 | |eth0 port1| +-------+ Host B |
2274 | Host A +------------+ switch |port3 +--------+
2275 | +------------+ | +--------+
2276 | |eth1 port2| +------------------+ Host C |
2277 +----------+ +----------+port4 +--------+
2278
2279
2280 Again, the switch may be a dedicated switch device, or another
2281host acting as a gateway. For our discussion, the important point is
2282that the majority of traffic from Host A is destined for other hosts
2283on the same local network (Hosts B and C in the above example).
2284
2285 In summary, in a gatewayed configuration, traffic to and from
2286the bonded device will be to the same MAC level peer on the network
2287(the gateway itself, i.e., the router), regardless of its final
2288destination. In a local configuration, traffic flows directly to and
2289from the final destinations, thus, each destination (Host B, Host C)
2290will be addressed directly by their individual MAC addresses.
2291
2292 This distinction between a gatewayed and a local network
2293configuration is important because many of the load balancing modes
2294available use the MAC addresses of the local network source and
2295destination to make load balancing decisions. The behavior of each
2296mode is described below.
2297
2298
Auke Kok6224e012006-06-08 11:15:35 -0700229912.1.1 MT Bonding Mode Selection for Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002300-----------------------------------------------------------
2301
2302 This configuration is the easiest to set up and to understand,
2303although you will have to decide which bonding mode best suits your
2304needs. The trade offs for each mode are detailed below:
2305
2306balance-rr: This mode is the only mode that will permit a single
2307 TCP/IP connection to stripe traffic across multiple
2308 interfaces. It is therefore the only mode that will allow a
2309 single TCP/IP stream to utilize more than one interface's
2310 worth of throughput. This comes at a cost, however: the
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002311 striping generally results in peer systems receiving packets out
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002312 of order, causing TCP/IP's congestion control system to kick
2313 in, often by retransmitting segments.
2314
2315 It is possible to adjust TCP/IP's congestion limits by
2316 altering the net.ipv4.tcp_reordering sysctl parameter. The
Eric Dumazetdca145f2014-10-27 21:45:24 -07002317 usual default value is 3. But keep in mind TCP stack is able
2318 to automatically increase this when it detects reorders.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002319
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002320 Note that the fraction of packets that will be delivered out of
2321 order is highly variable, and is unlikely to be zero. The level
2322 of reordering depends upon a variety of factors, including the
2323 networking interfaces, the switch, and the topology of the
2324 configuration. Speaking in general terms, higher speed network
2325 cards produce more reordering (due to factors such as packet
2326 coalescing), and a "many to many" topology will reorder at a
2327 higher rate than a "many slow to one fast" configuration.
2328
2329 Many switches do not support any modes that stripe traffic
2330 (instead choosing a port based upon IP or MAC level addresses);
2331 for those devices, traffic for a particular connection flowing
2332 through the switch to a balance-rr bond will not utilize greater
2333 than one interface's worth of bandwidth.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002334
2335 If you are utilizing protocols other than TCP/IP, UDP for
2336 example, and your application can tolerate out of order
2337 delivery, then this mode can allow for single stream datagram
2338 performance that scales near linearly as interfaces are added
2339 to the bond.
2340
2341 This mode requires the switch to have the appropriate ports
2342 configured for "etherchannel" or "trunking."
2343
2344active-backup: There is not much advantage in this network topology to
2345 the active-backup mode, as the inactive backup devices are all
2346 connected to the same peer as the primary. In this case, a
2347 load balancing mode (with link monitoring) will provide the
2348 same level of network availability, but with increased
2349 available bandwidth. On the plus side, active-backup mode
2350 does not require any configuration of the switch, so it may
2351 have value if the hardware available does not support any of
2352 the load balance modes.
2353
2354balance-xor: This mode will limit traffic such that packets destined
2355 for specific peers will always be sent over the same
2356 interface. Since the destination is determined by the MAC
2357 addresses involved, this mode works best in a "local" network
2358 configuration (as described above), with destinations all on
2359 the same local network. This mode is likely to be suboptimal
2360 if all your traffic is passed through a single router (i.e., a
2361 "gatewayed" network configuration, as described above).
2362
2363 As with balance-rr, the switch ports need to be configured for
2364 "etherchannel" or "trunking."
2365
2366broadcast: Like active-backup, there is not much advantage to this
2367 mode in this type of network topology.
2368
2369802.3ad: This mode can be a good choice for this type of network
2370 topology. The 802.3ad mode is an IEEE standard, so all peers
2371 that implement 802.3ad should interoperate well. The 802.3ad
2372 protocol includes automatic configuration of the aggregates,
2373 so minimal manual configuration of the switch is needed
2374 (typically only to designate that some set of devices is
2375 available for 802.3ad). The 802.3ad standard also mandates
2376 that frames be delivered in order (within certain limits), so
2377 in general single connections will not see misordering of
2378 packets. The 802.3ad mode does have some drawbacks: the
2379 standard mandates that all devices in the aggregate operate at
2380 the same speed and duplex. Also, as with all bonding load
2381 balance modes other than balance-rr, no single connection will
2382 be able to utilize more than a single interface's worth of
2383 bandwidth.
2384
2385 Additionally, the linux bonding 802.3ad implementation
Jianhua Xie92abf752014-07-17 14:16:26 +08002386 distributes traffic by peer (using an XOR of MAC addresses
2387 and packet type ID), so in a "gatewayed" configuration, all
2388 outgoing traffic will generally use the same device. Incoming
2389 traffic may also end up on a single device, but that is
2390 dependent upon the balancing policy of the peer's 8023.ad
2391 implementation. In a "local" configuration, traffic will be
2392 distributed across the devices in the bond.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002393
2394 Finally, the 802.3ad mode mandates the use of the MII monitor,
2395 therefore, the ARP monitor is not available in this mode.
2396
2397balance-tlb: The balance-tlb mode balances outgoing traffic by peer.
2398 Since the balancing is done according to MAC address, in a
2399 "gatewayed" configuration (as described above), this mode will
2400 send all traffic across a single device. However, in a
2401 "local" network configuration, this mode balances multiple
2402 local network peers across devices in a vaguely intelligent
2403 manner (not a simple XOR as in balance-xor or 802.3ad mode),
2404 so that mathematically unlucky MAC addresses (i.e., ones that
2405 XOR to the same value) will not all "bunch up" on a single
2406 interface.
2407
2408 Unlike 802.3ad, interfaces may be of differing speeds, and no
2409 special switch configuration is required. On the down side,
2410 in this mode all incoming traffic arrives over a single
2411 interface, this mode requires certain ethtool support in the
2412 network device driver of the slave interfaces, and the ARP
2413 monitor is not available.
2414
2415balance-alb: This mode is everything that balance-tlb is, and more.
2416 It has all of the features (and restrictions) of balance-tlb,
2417 and will also balance incoming traffic from local network
2418 peers (as described in the Bonding Module Options section,
2419 above).
2420
2421 The only additional down side to this mode is that the network
2422 device driver must support changing the hardware address while
2423 the device is open.
2424
Auke Kok6224e012006-06-08 11:15:35 -0700242512.1.2 MT Link Monitoring for Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002426----------------------------------------------------
2427
2428 The choice of link monitoring may largely depend upon which
2429mode you choose to use. The more advanced load balancing modes do not
2430support the use of the ARP monitor, and are thus restricted to using
2431the MII monitor (which does not provide as high a level of end to end
2432assurance as the ARP monitor).
2433
Auke Kok6224e012006-06-08 11:15:35 -0700243412.2 Maximum Throughput in a Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002435-----------------------------------------------------
2436
2437 Multiple switches may be utilized to optimize for throughput
2438when they are configured in parallel as part of an isolated network
2439between two or more systems, for example:
2440
2441 +-----------+
2442 | Host A |
2443 +-+---+---+-+
2444 | | |
2445 +--------+ | +---------+
2446 | | |
2447 +------+---+ +-----+----+ +-----+----+
2448 | Switch A | | Switch B | | Switch C |
2449 +------+---+ +-----+----+ +-----+----+
2450 | | |
2451 +--------+ | +---------+
2452 | | |
2453 +-+---+---+-+
2454 | Host B |
2455 +-----------+
2456
2457 In this configuration, the switches are isolated from one
2458another. One reason to employ a topology such as this is for an
2459isolated network with many hosts (a cluster configured for high
2460performance, for example), using multiple smaller switches can be more
2461cost effective than a single larger switch, e.g., on a network with 24
2462hosts, three 24 port switches can be significantly less expensive than
2463a single 72 port switch.
2464
2465 If access beyond the network is required, an individual host
2466can be equipped with an additional network device connected to an
2467external network; this host then additionally acts as a gateway.
2468
Auke Kok6224e012006-06-08 11:15:35 -0700246912.2.1 MT Bonding Mode Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002470-------------------------------------------------------------
2471
2472 In actual practice, the bonding mode typically employed in
2473configurations of this type is balance-rr. Historically, in this
2474network configuration, the usual caveats about out of order packet
2475delivery are mitigated by the use of network adapters that do not do
2476any kind of packet coalescing (via the use of NAPI, or because the
2477device itself does not generate interrupts until some number of
2478packets has arrived). When employed in this fashion, the balance-rr
2479mode allows individual connections between two hosts to effectively
2480utilize greater than one interface's bandwidth.
2481
Auke Kok6224e012006-06-08 11:15:35 -0700248212.2.2 MT Link Monitoring for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002483------------------------------------------------------
2484
2485 Again, in actual practice, the MII monitor is most often used
2486in this configuration, as performance is given preference over
2487availability. The ARP monitor will function in this topology, but its
2488advantages over the MII monitor are mitigated by the volume of probes
2489needed as the number of systems involved grows (remember that each
2490host in the network is configured with bonding).
2491
Auke Kok6224e012006-06-08 11:15:35 -0700249213. Switch Behavior Issues
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002493==========================
2494
Auke Kok6224e012006-06-08 11:15:35 -0700249513.1 Link Establishment and Failover Delays
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002496-------------------------------------------
2497
2498 Some switches exhibit undesirable behavior with regard to the
2499timing of link up and down reporting by the switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500
2501 First, when a link comes up, some switches may indicate that
2502the link is up (carrier available), but not pass traffic over the
2503interface for some period of time. This delay is typically due to
2504some type of autonegotiation or routing protocol, but may also occur
2505during switch initialization (e.g., during recovery after a switch
2506failure). If you find this to be a problem, specify an appropriate
2507value to the updelay bonding module option to delay the use of the
2508relevant interface(s).
2509
2510 Second, some switches may "bounce" the link state one or more
2511times while a link is changing state. This occurs most commonly while
2512the switch is initializing. Again, an appropriate updelay value may
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002513help.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514
2515 Note that when a bonding interface has no active links, the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002516driver will immediately reuse the first link that goes up, even if the
2517updelay parameter has been specified (the updelay is ignored in this
2518case). If there are slave interfaces waiting for the updelay timeout
2519to expire, the interface that first went into that state will be
2520immediately reused. This reduces down time of the network if the
2521value of updelay has been overestimated, and since this occurs only in
2522cases with no connectivity, there is no additional penalty for
2523ignoring the updelay.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002524
2525 In addition to the concerns about switch timings, if your
2526switches take a long time to go into backup mode, it may be desirable
2527to not activate a backup interface immediately after a link goes down.
2528Failover may be delayed via the downdelay bonding module option.
2529
Auke Kok6224e012006-06-08 11:15:35 -0700253013.2 Duplicated Incoming Packets
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002531--------------------------------
2532
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002533 NOTE: Starting with version 3.0.2, the bonding driver has logic to
2534suppress duplicate packets, which should largely eliminate this problem.
2535The following description is kept for reference.
2536
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002537 It is not uncommon to observe a short burst of duplicated
2538traffic when the bonding device is first used, or after it has been
2539idle for some period of time. This is most easily observed by issuing
2540a "ping" to some other host on the network, and noticing that the
2541output from ping flags duplicates (typically one per slave).
2542
2543 For example, on a bond in active-backup mode with five slaves
2544all connected to one switch, the output may appear as follows:
2545
2546# ping -n 10.0.4.2
2547PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data.
254864 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms
254964 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
255064 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
255164 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
255264 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
255364 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms
255464 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms
255564 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms
2556
2557 This is not due to an error in the bonding driver, rather, it
2558is a side effect of how many switches update their MAC forwarding
2559tables. Initially, the switch does not associate the MAC address in
2560the packet with a particular switch port, and so it may send the
2561traffic to all ports until its MAC forwarding table is updated. Since
2562the interfaces attached to the bond may occupy multiple ports on a
2563single switch, when the switch (temporarily) floods the traffic to all
2564ports, the bond device receives multiple copies of the same packet
2565(one per slave device).
2566
2567 The duplicated packet behavior is switch dependent, some
2568switches exhibit this, and some do not. On switches that display this
2569behavior, it can be induced by clearing the MAC forwarding table (on
2570most Cisco switches, the privileged command "clear mac address-table
2571dynamic" will accomplish this).
2572
Auke Kok6224e012006-06-08 11:15:35 -0700257314. Hardware Specific Considerations
Linus Torvalds1da177e2005-04-16 15:20:36 -07002574====================================
2575
2576 This section contains additional information for configuring
2577bonding on specific hardware platforms, or for interfacing bonding
2578with particular switches or other devices.
2579
Auke Kok6224e012006-06-08 11:15:35 -0700258014.1 IBM BladeCenter
Linus Torvalds1da177e2005-04-16 15:20:36 -07002581--------------------
2582
2583 This applies to the JS20 and similar systems.
2584
2585 On the JS20 blades, the bonding driver supports only
2586balance-rr, active-backup, balance-tlb and balance-alb modes. This is
2587largely due to the network topology inside the BladeCenter, detailed
2588below.
2589
2590JS20 network adapter information
2591--------------------------------
2592
2593 All JS20s come with two Broadcom Gigabit Ethernet ports
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002594integrated on the planar (that's "motherboard" in IBM-speak). In the
2595BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to
2596I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2.
2597An add-on Broadcom daughter card can be installed on a JS20 to provide
2598two more Gigabit Ethernet ports. These ports, eth2 and eth3, are
2599wired to I/O Modules 3 and 4, respectively.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600
2601 Each I/O Module may contain either a switch or a passthrough
2602module (which allows ports to be directly connected to an external
2603switch). Some bonding modes require a specific BladeCenter internal
2604network topology in order to function; these are detailed below.
2605
2606 Additional BladeCenter-specific networking information can be
2607found in two IBM Redbooks (www.ibm.com/redbooks):
2608
2609"IBM eServer BladeCenter Networking Options"
2610"IBM eServer BladeCenter Layer 2-7 Network Switching"
2611
2612BladeCenter networking configuration
2613------------------------------------
2614
2615 Because a BladeCenter can be configured in a very large number
2616of ways, this discussion will be confined to describing basic
2617configurations.
2618
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002619 Normally, Ethernet Switch Modules (ESMs) are used in I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07002620modules 1 and 2. In this configuration, the eth0 and eth1 ports of a
2621JS20 will be connected to different internal switches (in the
2622respective I/O modules).
2623
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002624 A passthrough module (OPM or CPM, optical or copper,
2625passthrough module) connects the I/O module directly to an external
2626switch. By using PMs in I/O module #1 and #2, the eth0 and eth1
2627interfaces of a JS20 can be redirected to the outside world and
2628connected to a common external switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002629
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002630 Depending upon the mix of ESMs and PMs, the network will
2631appear to bonding as either a single switch topology (all PMs) or as a
2632multiple switch topology (one or more ESMs, zero or more PMs). It is
2633also possible to connect ESMs together, resulting in a configuration
2634much like the example in "High Availability in a Multiple Switch
2635Topology," above.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002636
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002637Requirements for specific modes
2638-------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002639
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002640 The balance-rr mode requires the use of passthrough modules
2641for devices in the bond, all connected to an common external switch.
2642That switch must be configured for "etherchannel" or "trunking" on the
Linus Torvalds1da177e2005-04-16 15:20:36 -07002643appropriate ports, as is usual for balance-rr.
2644
2645 The balance-alb and balance-tlb modes will function with
2646either switch modules or passthrough modules (or a mix). The only
2647specific requirement for these modes is that all network interfaces
2648must be able to reach all destinations for traffic sent over the
2649bonding device (i.e., the network must converge at some point outside
2650the BladeCenter).
2651
2652 The active-backup mode has no additional requirements.
2653
2654Link monitoring issues
2655----------------------
2656
2657 When an Ethernet Switch Module is in place, only the ARP
2658monitor will reliably detect link loss to an external switch. This is
2659nothing unusual, but examination of the BladeCenter cabinet would
2660suggest that the "external" network ports are the ethernet ports for
2661the system, when it fact there is a switch between these "external"
2662ports and the devices on the JS20 system itself. The MII monitor is
2663only able to detect link failures between the ESM and the JS20 system.
2664
2665 When a passthrough module is in place, the MII monitor does
2666detect failures to the "external" port, which is then directly
2667connected to the JS20 system.
2668
2669Other concerns
2670--------------
2671
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002672 The Serial Over LAN (SoL) link is established over the primary
Linus Torvalds1da177e2005-04-16 15:20:36 -07002673ethernet (eth0) only, therefore, any loss of link to eth0 will result
2674in losing your SoL connection. It will not fail over with other
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002675network traffic, as the SoL system is beyond the control of the
2676bonding driver.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002677
2678 It may be desirable to disable spanning tree on the switch
2679(either the internal Ethernet Switch Module, or an external switch) to
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002680avoid fail-over delay issues when using bonding.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002681
2682
Auke Kok6224e012006-06-08 11:15:35 -0700268315. Frequently Asked Questions
Linus Torvalds1da177e2005-04-16 15:20:36 -07002684==============================
2685
26861. Is it SMP safe?
2687
2688 Yes. The old 2.0.xx channel bonding patch was not SMP safe.
2689The new driver was designed to be SMP safe from the start.
2690
26912. What type of cards will work with it?
2692
2693 Any Ethernet type cards (you can even mix cards - a Intel
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002694EtherExpress PRO/100 and a 3com 3c905b, for example). For most modes,
2695devices need not be of the same speed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002696
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002697 Starting with version 3.2.1, bonding also supports Infiniband
2698slaves in active-backup mode.
2699
Linus Torvalds1da177e2005-04-16 15:20:36 -070027003. How many bonding devices can I have?
2701
2702 There is no limit.
2703
27044. How many slaves can a bonding device have?
2705
2706 This is limited only by the number of network interfaces Linux
2707supports and/or the number of network cards you can place in your
2708system.
2709
27105. What happens when a slave link dies?
2711
2712 If link monitoring is enabled, then the failing device will be
2713disabled. The active-backup mode will fail over to a backup link, and
2714other modes will ignore the failed link. The link will continue to be
2715monitored, and should it recover, it will rejoin the bond (in whatever
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002716manner is appropriate for the mode). See the sections on High
2717Availability and the documentation for each mode for additional
2718information.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002719
2720 Link monitoring can be enabled via either the miimon or
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002721arp_interval parameters (described in the module parameters section,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002722above). In general, miimon monitors the carrier state as sensed by
2723the underlying network device, and the arp monitor (arp_interval)
2724monitors connectivity to another host on the local network.
2725
2726 If no link monitoring is configured, the bonding driver will
2727be unable to detect link failures, and will assume that all links are
2728always available. This will likely result in lost packets, and a
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002729resulting degradation of performance. The precise performance loss
Linus Torvalds1da177e2005-04-16 15:20:36 -07002730depends upon the bonding mode and network configuration.
2731
27326. Can bonding be used for High Availability?
2733
2734 Yes. See the section on High Availability for details.
2735
27367. Which switches/systems does it work with?
2737
2738 The full answer to this depends upon the desired mode.
2739
2740 In the basic balance modes (balance-rr and balance-xor), it
2741works with any system that supports etherchannel (also called
2742trunking). Most managed switches currently available have such
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002743support, and many unmanaged switches as well.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002744
2745 The advanced balance modes (balance-tlb and balance-alb) do
2746not have special switch requirements, but do need device drivers that
2747support specific features (described in the appropriate section under
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002748module parameters, above).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002749
Auke Kok6224e012006-06-08 11:15:35 -07002750 In 802.3ad mode, it works with systems that support IEEE
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751802.3ad Dynamic Link Aggregation. Most managed and many unmanaged
2752switches currently available support 802.3ad.
2753
2754 The active-backup mode should work with any Layer-II switch.
2755
27568. Where does a bonding device get its MAC address from?
2757
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002758 When using slave devices that have fixed MAC addresses, or when
2759the fail_over_mac option is enabled, the bonding device's MAC address is
2760the MAC address of the active slave.
2761
2762 For other configurations, if not explicitly configured (with
2763ifconfig or ip link), the MAC address of the bonding device is taken from
2764its first slave device. This MAC address is then passed to all following
2765slaves and remains persistent (even if the first slave is removed) until
2766the bonding device is brought down or reconfigured.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767
2768 If you wish to change the MAC address, you can set it with
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002769ifconfig or ip link:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002770
2771# ifconfig bond0 hw ether 00:11:22:33:44:55
2772
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002773# ip link set bond0 address 66:77:88:99:aa:bb
2774
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775 The MAC address can be also changed by bringing down/up the
2776device and then changing its slaves (or their order):
2777
2778# ifconfig bond0 down ; modprobe -r bonding
2779# ifconfig bond0 .... up
2780# ifenslave bond0 eth...
2781
2782 This method will automatically take the address from the next
2783slave that is added.
2784
2785 To restore your slaves' MAC addresses, you need to detach them
2786from the bond (`ifenslave -d bond0 eth0'). The bonding driver will
2787then restore the MAC addresses that the slaves had before they were
2788enslaved.
2789
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700279016. Resources and Links
Linus Torvalds1da177e2005-04-16 15:20:36 -07002791=======================
2792
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002793 The latest version of the bonding driver can be found in the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -07002794version of the linux kernel, found on http://kernel.org
2795
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002796 The latest version of this document can be found in the latest kernel
2797source (named Documentation/networking/bonding.txt).
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002798
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002799 Discussions regarding the usage of the bonding driver take place on the
2800bonding-devel mailing list, hosted at sourceforge.net. If you have questions or
2801problems, post them to the list. The list address is:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002802
2803bonding-devel@lists.sourceforge.net
2804
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002805 The administrative interface (to subscribe or unsubscribe) can
2806be found at:
2807
Linus Torvalds1da177e2005-04-16 15:20:36 -07002808https://lists.sourceforge.net/lists/listinfo/bonding-devel
2809
Rick Jonesf8b72d32012-07-20 10:51:37 +00002810 Discussions regarding the development of the bonding driver take place
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002811on the main Linux network mailing list, hosted at vger.kernel.org. The list
2812address is:
2813
2814netdev@vger.kernel.org
2815
2816 The administrative interface (to subscribe or unsubscribe) can
2817be found at:
2818
2819http://vger.kernel.org/vger-lists.html#netdev
2820
Linus Torvalds1da177e2005-04-16 15:20:36 -07002821Donald Becker's Ethernet Drivers and diag programs may be found at :
Justin P. Mattock0ea6e612010-07-23 20:51:24 -07002822 - http://web.archive.org/web/*/http://www.scyld.com/network/
Linus Torvalds1da177e2005-04-16 15:20:36 -07002823
2824You will also find a lot of information regarding Ethernet, NWay, MII,
2825etc. at www.scyld.com.
2826
2827-- END --