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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
Linus Torvalds1da177e2005-04-16 15:20:36 -070054
Auke Kok6224e012006-06-08 11:15:35 -0700554. Querying Bonding Configuration
564.1 Bonding Configuration
574.2 Network Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -070058
Auke Kok6224e012006-06-08 11:15:35 -0700595. Switch Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
Auke Kok6224e012006-06-08 11:15:35 -0700616. 802.1q VLAN Support
Linus Torvalds1da177e2005-04-16 15:20:36 -070062
Auke Kok6224e012006-06-08 11:15:35 -0700637. Link Monitoring
647.1 ARP Monitor Operation
657.2 Configuring Multiple ARP Targets
667.3 MII Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -070067
Auke Kok6224e012006-06-08 11:15:35 -0700688. Potential Trouble Sources
698.1 Adventures in Routing
708.2 Ethernet Device Renaming
718.3 Painfully Slow Or No Failed Link Detection By Miimon
Linus Torvalds1da177e2005-04-16 15:20:36 -070072
Auke Kok6224e012006-06-08 11:15:35 -0700739. SNMP agents
Linus Torvalds1da177e2005-04-16 15:20:36 -070074
Auke Kok6224e012006-06-08 11:15:35 -07007510. Promiscuous mode
Linus Torvalds1da177e2005-04-16 15:20:36 -070076
Auke Kok6224e012006-06-08 11:15:35 -07007711. Configuring Bonding for High Availability
7811.1 High Availability in a Single Switch Topology
7911.2 High Availability in a Multiple Switch Topology
8011.2.1 HA Bonding Mode Selection for Multiple Switch Topology
8111.2.2 HA Link Monitoring for Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -070082
Auke Kok6224e012006-06-08 11:15:35 -07008312. Configuring Bonding for Maximum Throughput
8412.1 Maximum Throughput in a Single Switch Topology
8512.1.1 MT Bonding Mode Selection for Single Switch Topology
8612.1.2 MT Link Monitoring for Single Switch Topology
8712.2 Maximum Throughput in a Multiple Switch Topology
8812.2.1 MT Bonding Mode Selection for Multiple Switch Topology
8912.2.2 MT Link Monitoring for Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -070090
Auke Kok6224e012006-06-08 11:15:35 -07009113. Switch Behavior Issues
9213.1 Link Establishment and Failover Delays
9313.2 Duplicated Incoming Packets
Linus Torvalds1da177e2005-04-16 15:20:36 -070094
Auke Kok6224e012006-06-08 11:15:35 -07009514. Hardware Specific Considerations
9614.1 IBM BladeCenter
Jay Vosburgh00354cf2005-07-21 12:18:02 -070097
Auke Kok6224e012006-06-08 11:15:35 -07009815. Frequently Asked Questions
Jay Vosburgh00354cf2005-07-21 12:18:02 -070099
Auke Kok6224e012006-06-08 11:15:35 -070010016. Resources and Links
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101
102
1031. Bonding Driver Installation
104==============================
105
106 Most popular distro kernels ship with the bonding driver
Cong Wangb1098bb2013-05-27 15:49:16 +0000107already available as a module. If your distro does not, or you
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108have need to compile bonding from source (e.g., configuring and
109installing a mainline kernel from kernel.org), you'll need to perform
110the following steps:
111
1121.1 Configure and build the kernel with bonding
113-----------------------------------------------
114
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700115 The current version of the bonding driver is available in the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116drivers/net/bonding subdirectory of the most recent kernel source
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700117(which is available on http://kernel.org). Most users "rolling their
118own" will want to use the most recent kernel from kernel.org.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119
120 Configure kernel with "make menuconfig" (or "make xconfig" or
121"make config"), then select "Bonding driver support" in the "Network
122device support" section. It is recommended that you configure the
123driver as module since it is currently the only way to pass parameters
124to the driver or configure more than one bonding device.
125
Cong Wangb1098bb2013-05-27 15:49:16 +0000126 Build and install the new kernel and modules.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700127
Cong Wangb1098bb2013-05-27 15:49:16 +00001281.2 Bonding Control Utility
Linus Torvalds1da177e2005-04-16 15:20:36 -0700129-------------------------------------
130
Cong Wangb1098bb2013-05-27 15:49:16 +0000131 It is recommended to configure bonding via iproute2 (netlink)
132or sysfs, the old ifenslave control utility is obsolete.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700133
1342. Bonding Driver Options
135=========================
136
Jay Vosburgh9a6c6862007-11-13 20:25:48 -0800137 Options for the bonding driver are supplied as parameters to the
138bonding module at load time, or are specified via sysfs.
139
140 Module options may be given as command line arguments to the
141insmod or modprobe command, but are usually specified in either the
Lucas De Marchi970e2482012-03-30 13:37:16 -0700142/etc/modrobe.d/*.conf configuration files, or in a distro-specific
143configuration file (some of which are detailed in the next section).
Jay Vosburgh9a6c6862007-11-13 20:25:48 -0800144
145 Details on bonding support for sysfs is provided in the
146"Configuring Bonding Manually via Sysfs" section, below.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147
148 The available bonding driver parameters are listed below. If a
149parameter is not specified the default value is used. When initially
150configuring a bond, it is recommended "tail -f /var/log/messages" be
151run in a separate window to watch for bonding driver error messages.
152
153 It is critical that either the miimon or arp_interval and
154arp_ip_target parameters be specified, otherwise serious network
155degradation will occur during link failures. Very few devices do not
156support at least miimon, so there is really no reason not to use it.
157
158 Options with textual values will accept either the text name
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700159or, for backwards compatibility, the option value. E.g.,
160"mode=802.3ad" and "mode=4" set the same mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
162 The parameters are as follows:
163
Nicolas de Pesloüan1ba9ac72011-12-26 13:35:24 +0000164active_slave
165
166 Specifies the new active slave for modes that support it
167 (active-backup, balance-alb and balance-tlb). Possible values
168 are the name of any currently enslaved interface, or an empty
169 string. If a name is given, the slave and its link must be up in order
170 to be selected as the new active slave. If an empty string is
171 specified, the current active slave is cleared, and a new active
172 slave is selected automatically.
173
174 Note that this is only available through the sysfs interface. No module
175 parameter by this name exists.
176
177 The normal value of this option is the name of the currently
178 active slave, or the empty string if there is no active slave or
179 the current mode does not use an active slave.
180
Jay Vosburghfd989c82008-11-04 17:51:16 -0800181ad_select
182
183 Specifies the 802.3ad aggregation selection logic to use. The
184 possible values and their effects are:
185
186 stable or 0
187
188 The active aggregator is chosen by largest aggregate
189 bandwidth.
190
191 Reselection of the active aggregator occurs only when all
192 slaves of the active aggregator are down or the active
193 aggregator has no slaves.
194
195 This is the default value.
196
197 bandwidth or 1
198
199 The active aggregator is chosen by largest aggregate
200 bandwidth. Reselection occurs if:
201
202 - A slave is added to or removed from the bond
203
204 - Any slave's link state changes
205
206 - Any slave's 802.3ad association state changes
207
Matt LaPlante19f59462009-04-27 15:06:31 +0200208 - The bond's administrative state changes to up
Jay Vosburghfd989c82008-11-04 17:51:16 -0800209
210 count or 2
211
212 The active aggregator is chosen by the largest number of
213 ports (slaves). Reselection occurs as described under the
214 "bandwidth" setting, above.
215
216 The bandwidth and count selection policies permit failover of
217 802.3ad aggregations when partial failure of the active aggregator
218 occurs. This keeps the aggregator with the highest availability
219 (either in bandwidth or in number of ports) active at all times.
220
221 This option was added in bonding version 3.4.0.
222
Nicolas de Pesloüan025890b2011-08-06 07:06:39 +0000223all_slaves_active
224
225 Specifies that duplicate frames (received on inactive ports) should be
226 dropped (0) or delivered (1).
227
228 Normally, bonding will drop duplicate frames (received on inactive
229 ports), which is desirable for most users. But there are some times
230 it is nice to allow duplicate frames to be delivered.
231
232 The default value is 0 (drop duplicate frames received on inactive
233 ports).
234
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235arp_interval
236
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700237 Specifies the ARP link monitoring frequency in milliseconds.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700238
239 The ARP monitor works by periodically checking the slave
240 devices to determine whether they have sent or received
241 traffic recently (the precise criteria depends upon the
242 bonding mode, and the state of the slave). Regular traffic is
243 generated via ARP probes issued for the addresses specified by
244 the arp_ip_target option.
245
246 This behavior can be modified by the arp_validate option,
247 below.
248
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700249 If ARP monitoring is used in an etherchannel compatible mode
250 (modes 0 and 2), the switch should be configured in a mode
251 that evenly distributes packets across all links. If the
252 switch is configured to distribute the packets in an XOR
Linus Torvalds1da177e2005-04-16 15:20:36 -0700253 fashion, all replies from the ARP targets will be received on
254 the same link which could cause the other team members to
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700255 fail. ARP monitoring should not be used in conjunction with
256 miimon. A value of 0 disables ARP monitoring. The default
Linus Torvalds1da177e2005-04-16 15:20:36 -0700257 value is 0.
258
259arp_ip_target
260
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700261 Specifies the IP addresses to use as ARP monitoring peers when
262 arp_interval is > 0. These are the targets of the ARP request
263 sent to determine the health of the link to the targets.
264 Specify these values in ddd.ddd.ddd.ddd format. Multiple IP
265 addresses must be separated by a comma. At least one IP
266 address must be given for ARP monitoring to function. The
267 maximum number of targets that can be specified is 16. The
268 default value is no IP addresses.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700270arp_validate
271
272 Specifies whether or not ARP probes and replies should be
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100273 validated in any mode that supports arp monitoring, or whether
274 non-ARP traffic should be filtered (disregarded) for link
275 monitoring purposes.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700276
277 Possible values are:
278
279 none or 0
280
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100281 No validation or filtering is performed.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700282
283 active or 1
284
285 Validation is performed only for the active slave.
286
287 backup or 2
288
289 Validation is performed only for backup slaves.
290
291 all or 3
292
293 Validation is performed for all slaves.
294
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100295 filter or 4
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700296
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100297 Filtering is applied to all slaves. No validation is
298 performed.
Veaceslav Falicod7d35c62013-06-24 11:49:33 +0200299
Veaceslav Falico52f65ef2014-02-18 07:48:41 +0100300 filter_active or 5
301
302 Filtering is applied to all slaves, validation is performed
303 only for the active slave.
304
305 filter_backup or 6
306
307 Filtering is applied to all slaves, validation is performed
308 only for backup slaves.
309
310 Validation:
311
312 Enabling validation causes the ARP monitor to examine the incoming
313 ARP requests and replies, and only consider a slave to be up if it
314 is receiving the appropriate ARP traffic.
315
316 For an active slave, the validation checks ARP replies to confirm
317 that they were generated by an arp_ip_target. Since backup slaves
318 do not typically receive these replies, the validation performed
319 for backup slaves is on the broadcast ARP request sent out via the
320 active slave. It is possible that some switch or network
321 configurations may result in situations wherein the backup slaves
322 do not receive the ARP requests; in such a situation, validation
323 of backup slaves must be disabled.
324
325 The validation of ARP requests on backup slaves is mainly helping
326 bonding to decide which slaves are more likely to work in case of
327 the active slave failure, it doesn't really guarantee that the
328 backup slave will work if it's selected as the next active slave.
329
330 Validation is useful in network configurations in which multiple
331 bonding hosts are concurrently issuing ARPs to one or more targets
332 beyond a common switch. Should the link between the switch and
333 target fail (but not the switch itself), the probe traffic
334 generated by the multiple bonding instances will fool the standard
335 ARP monitor into considering the links as still up. Use of
336 validation can resolve this, as the ARP monitor will only consider
337 ARP requests and replies associated with its own instance of
338 bonding.
339
340 Filtering:
341
342 Enabling filtering causes the ARP monitor to only use incoming ARP
343 packets for link availability purposes. Arriving packets that are
344 not ARPs are delivered normally, but do not count when determining
345 if a slave is available.
346
347 Filtering operates by only considering the reception of ARP
348 packets (any ARP packet, regardless of source or destination) when
349 determining if a slave has received traffic for link availability
350 purposes.
351
352 Filtering is useful in network configurations in which significant
353 levels of third party broadcast traffic would fool the standard
354 ARP monitor into considering the links as still up. Use of
355 filtering can resolve this, as only ARP traffic is considered for
356 link availability purposes.
Jay Vosburghf5b2b962006-09-22 21:54:53 -0700357
358 This option was added in bonding version 3.1.0.
359
Veaceslav Falico8599b522013-06-24 11:49:34 +0200360arp_all_targets
361
362 Specifies the quantity of arp_ip_targets that must be reachable
363 in order for the ARP monitor to consider a slave as being up.
364 This option affects only active-backup mode for slaves with
365 arp_validation enabled.
366
367 Possible values are:
368
369 any or 0
370
371 consider the slave up only when any of the arp_ip_targets
372 is reachable
373
374 all or 1
375
376 consider the slave up only when all of the arp_ip_targets
377 are reachable
378
Linus Torvalds1da177e2005-04-16 15:20:36 -0700379downdelay
380
381 Specifies the time, in milliseconds, to wait before disabling
382 a slave after a link failure has been detected. This option
383 is only valid for the miimon link monitor. The downdelay
384 value should be a multiple of the miimon value; if not, it
385 will be rounded down to the nearest multiple. The default
386 value is 0.
387
Jay Vosburghdd957c52007-10-09 19:57:24 -0700388fail_over_mac
389
390 Specifies whether active-backup mode should set all slaves to
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700391 the same MAC address at enslavement (the traditional
392 behavior), or, when enabled, perform special handling of the
393 bond's MAC address in accordance with the selected policy.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700394
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700395 Possible values are:
Jay Vosburghdd957c52007-10-09 19:57:24 -0700396
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700397 none or 0
Jay Vosburghdd957c52007-10-09 19:57:24 -0700398
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700399 This setting disables fail_over_mac, and causes
400 bonding to set all slaves of an active-backup bond to
401 the same MAC address at enslavement time. This is the
402 default.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700403
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700404 active or 1
Jay Vosburghdd957c52007-10-09 19:57:24 -0700405
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700406 The "active" fail_over_mac policy indicates that the
407 MAC address of the bond should always be the MAC
408 address of the currently active slave. The MAC
409 address of the slaves is not changed; instead, the MAC
410 address of the bond changes during a failover.
411
412 This policy is useful for devices that cannot ever
413 alter their MAC address, or for devices that refuse
414 incoming broadcasts with their own source MAC (which
415 interferes with the ARP monitor).
416
417 The down side of this policy is that every device on
418 the network must be updated via gratuitous ARP,
419 vs. just updating a switch or set of switches (which
420 often takes place for any traffic, not just ARP
421 traffic, if the switch snoops incoming traffic to
422 update its tables) for the traditional method. If the
423 gratuitous ARP is lost, communication may be
424 disrupted.
425
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300426 When this policy is used in conjunction with the mii
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700427 monitor, devices which assert link up prior to being
428 able to actually transmit and receive are particularly
Matt LaPlante19f59462009-04-27 15:06:31 +0200429 susceptible to loss of the gratuitous ARP, and an
Jay Vosburgh3915c1e82008-05-17 21:10:14 -0700430 appropriate updelay setting may be required.
431
432 follow or 2
433
434 The "follow" fail_over_mac policy causes the MAC
435 address of the bond to be selected normally (normally
436 the MAC address of the first slave added to the bond).
437 However, the second and subsequent slaves are not set
438 to this MAC address while they are in a backup role; a
439 slave is programmed with the bond's MAC address at
440 failover time (and the formerly active slave receives
441 the newly active slave's MAC address).
442
443 This policy is useful for multiport devices that
444 either become confused or incur a performance penalty
445 when multiple ports are programmed with the same MAC
446 address.
447
448
449 The default policy is none, unless the first slave cannot
450 change its MAC address, in which case the active policy is
451 selected by default.
452
453 This option may be modified via sysfs only when no slaves are
454 present in the bond.
455
456 This option was added in bonding version 3.2.0. The "follow"
457 policy was added in bonding version 3.3.0.
Jay Vosburghdd957c52007-10-09 19:57:24 -0700458
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459lacp_rate
460
461 Option specifying the rate in which we'll ask our link partner
462 to transmit LACPDU packets in 802.3ad mode. Possible values
463 are:
464
465 slow or 0
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700466 Request partner to transmit LACPDUs every 30 seconds
Linus Torvalds1da177e2005-04-16 15:20:36 -0700467
468 fast or 1
469 Request partner to transmit LACPDUs every 1 second
470
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700471 The default is slow.
472
Linus Torvalds1da177e2005-04-16 15:20:36 -0700473max_bonds
474
475 Specifies the number of bonding devices to create for this
476 instance of the bonding driver. E.g., if max_bonds is 3, and
477 the bonding driver is not already loaded, then bond0, bond1
Jay Vosburghb8a97872008-06-13 18:12:04 -0700478 and bond2 will be created. The default value is 1. Specifying
479 a value of 0 will load bonding, but will not create any devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480
481miimon
482
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700483 Specifies the MII link monitoring frequency in milliseconds.
484 This determines how often the link state of each slave is
485 inspected for link failures. A value of zero disables MII
486 link monitoring. A value of 100 is a good starting point.
487 The use_carrier option, below, affects how the link state is
Linus Torvalds1da177e2005-04-16 15:20:36 -0700488 determined. See the High Availability section for additional
489 information. The default value is 0.
490
Nicolas de Pesloüan025890b2011-08-06 07:06:39 +0000491min_links
492
493 Specifies the minimum number of links that must be active before
494 asserting carrier. It is similar to the Cisco EtherChannel min-links
495 feature. This allows setting the minimum number of member ports that
496 must be up (link-up state) before marking the bond device as up
497 (carrier on). This is useful for situations where higher level services
498 such as clustering want to ensure a minimum number of low bandwidth
499 links are active before switchover. This option only affect 802.3ad
500 mode.
501
502 The default value is 0. This will cause carrier to be asserted (for
503 802.3ad mode) whenever there is an active aggregator, regardless of the
504 number of available links in that aggregator. Note that, because an
505 aggregator cannot be active without at least one available link,
506 setting this option to 0 or to 1 has the exact same effect.
507
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508mode
509
510 Specifies one of the bonding policies. The default is
511 balance-rr (round robin). Possible values are:
512
513 balance-rr or 0
514
515 Round-robin policy: Transmit packets in sequential
516 order from the first available slave through the
517 last. This mode provides load balancing and fault
518 tolerance.
519
520 active-backup or 1
521
522 Active-backup policy: Only one slave in the bond is
523 active. A different slave becomes active if, and only
524 if, the active slave fails. The bond's MAC address is
525 externally visible on only one port (network adapter)
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700526 to avoid confusing the switch.
527
528 In bonding version 2.6.2 or later, when a failover
529 occurs in active-backup mode, bonding will issue one
530 or more gratuitous ARPs on the newly active slave.
Auke Kok6224e012006-06-08 11:15:35 -0700531 One gratuitous ARP is issued for the bonding master
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700532 interface and each VLAN interfaces configured above
533 it, provided that the interface has at least one IP
534 address configured. Gratuitous ARPs issued for VLAN
535 interfaces are tagged with the appropriate VLAN id.
536
537 This mode provides fault tolerance. The primary
538 option, documented below, affects the behavior of this
539 mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540
541 balance-xor or 2
542
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700543 XOR policy: Transmit based on the selected transmit
544 hash policy. The default policy is a simple [(source
Jianhua Xie92abf752014-07-17 14:16:26 +0800545 MAC address XOR'd with destination MAC address XOR
546 packet type ID) modulo slave count]. Alternate transmit
547 policies may be selected via the xmit_hash_policy option,
548 described below.
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700549
550 This mode provides load balancing and fault tolerance.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700551
552 broadcast or 3
553
554 Broadcast policy: transmits everything on all slave
555 interfaces. This mode provides fault tolerance.
556
557 802.3ad or 4
558
559 IEEE 802.3ad Dynamic link aggregation. Creates
560 aggregation groups that share the same speed and
561 duplex settings. Utilizes all slaves in the active
562 aggregator according to the 802.3ad specification.
563
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700564 Slave selection for outgoing traffic is done according
565 to the transmit hash policy, which may be changed from
566 the default simple XOR policy via the xmit_hash_policy
567 option, documented below. Note that not all transmit
568 policies may be 802.3ad compliant, particularly in
569 regards to the packet mis-ordering requirements of
570 section 43.2.4 of the 802.3ad standard. Differing
571 peer implementations will have varying tolerances for
572 noncompliance.
573
574 Prerequisites:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700575
576 1. Ethtool support in the base drivers for retrieving
577 the speed and duplex of each slave.
578
579 2. A switch that supports IEEE 802.3ad Dynamic link
580 aggregation.
581
582 Most switches will require some type of configuration
583 to enable 802.3ad mode.
584
585 balance-tlb or 5
586
587 Adaptive transmit load balancing: channel bonding that
Mahesh Bandeware9f0fb82014-04-22 16:30:22 -0700588 does not require any special switch support.
589
590 In tlb_dynamic_lb=1 mode; the outgoing traffic is
591 distributed according to the current load (computed
592 relative to the speed) on each slave.
593
594 In tlb_dynamic_lb=0 mode; the load balancing based on
595 current load is disabled and the load is distributed
596 only using the hash distribution.
597
598 Incoming traffic is received by the current slave.
599 If the receiving slave fails, another slave takes over
600 the MAC address of the failed receiving slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700601
602 Prerequisite:
603
604 Ethtool support in the base drivers for retrieving the
605 speed of each slave.
606
607 balance-alb or 6
608
609 Adaptive load balancing: includes balance-tlb plus
610 receive load balancing (rlb) for IPV4 traffic, and
611 does not require any special switch support. The
612 receive load balancing is achieved by ARP negotiation.
613 The bonding driver intercepts the ARP Replies sent by
614 the local system on their way out and overwrites the
615 source hardware address with the unique hardware
616 address of one of the slaves in the bond such that
617 different peers use different hardware addresses for
618 the server.
619
620 Receive traffic from connections created by the server
621 is also balanced. When the local system sends an ARP
622 Request the bonding driver copies and saves the peer's
623 IP information from the ARP packet. When the ARP
624 Reply arrives from the peer, its hardware address is
625 retrieved and the bonding driver initiates an ARP
626 reply to this peer assigning it to one of the slaves
627 in the bond. A problematic outcome of using ARP
628 negotiation for balancing is that each time that an
629 ARP request is broadcast it uses the hardware address
630 of the bond. Hence, peers learn the hardware address
631 of the bond and the balancing of receive traffic
632 collapses to the current slave. This is handled by
633 sending updates (ARP Replies) to all the peers with
634 their individually assigned hardware address such that
635 the traffic is redistributed. Receive traffic is also
636 redistributed when a new slave is added to the bond
637 and when an inactive slave is re-activated. The
638 receive load is distributed sequentially (round robin)
639 among the group of highest speed slaves in the bond.
640
641 When a link is reconnected or a new slave joins the
642 bond the receive traffic is redistributed among all
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700643 active slaves in the bond by initiating ARP Replies
Auke Kok6224e012006-06-08 11:15:35 -0700644 with the selected MAC address to each of the
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 clients. The updelay parameter (detailed below) must
646 be set to a value equal or greater than the switch's
647 forwarding delay so that the ARP Replies sent to the
648 peers will not be blocked by the switch.
649
650 Prerequisites:
651
652 1. Ethtool support in the base drivers for retrieving
653 the speed of each slave.
654
655 2. Base driver support for setting the hardware
656 address of a device while it is open. This is
657 required so that there will always be one slave in the
658 team using the bond hardware address (the
659 curr_active_slave) while having a unique hardware
660 address for each slave in the bond. If the
661 curr_active_slave fails its hardware address is
662 swapped with the new curr_active_slave that was
663 chosen.
664
Jay Vosburghb59f9f72008-06-13 18:12:03 -0700665num_grat_arp
Brian Haley305d5522008-11-04 17:51:14 -0800666num_unsol_na
667
Ben Hutchingsad246c92011-04-26 15:25:52 +0000668 Specify the number of peer notifications (gratuitous ARPs and
669 unsolicited IPv6 Neighbor Advertisements) to be issued after a
670 failover event. As soon as the link is up on the new slave
671 (possibly immediately) a peer notification is sent on the
672 bonding device and each VLAN sub-device. This is repeated at
673 each link monitor interval (arp_interval or miimon, whichever
674 is active) if the number is greater than 1.
Brian Haley305d5522008-11-04 17:51:14 -0800675
Ben Hutchingsad246c92011-04-26 15:25:52 +0000676 The valid range is 0 - 255; the default value is 1. These options
677 affect only the active-backup mode. These options were added for
678 bonding versions 3.3.0 and 3.4.0 respectively.
679
Jesper Juhl8fb4e132011-08-01 17:59:44 -0700680 From Linux 3.0 and bonding version 3.7.1, these notifications
Ben Hutchingsad246c92011-04-26 15:25:52 +0000681 are generated by the ipv4 and ipv6 code and the numbers of
682 repetitions cannot be set independently.
Brian Haley305d5522008-11-04 17:51:14 -0800683
Nikolay Aleksandrov12465fb2013-11-05 13:51:42 +0100684packets_per_slave
685
686 Specify the number of packets to transmit through a slave before
687 moving to the next one. When set to 0 then a slave is chosen at
688 random.
689
690 The valid range is 0 - 65535; the default value is 1. This option
691 has effect only in balance-rr mode.
692
Linus Torvalds1da177e2005-04-16 15:20:36 -0700693primary
694
695 A string (eth0, eth2, etc) specifying which slave is the
696 primary device. The specified device will always be the
697 active slave while it is available. Only when the primary is
698 off-line will alternate devices be used. This is useful when
699 one slave is preferred over another, e.g., when one slave has
700 higher throughput than another.
701
dingtianhonge1d206a2014-01-18 16:28:57 +0800702 The primary option is only valid for active-backup(1),
703 balance-tlb (5) and balance-alb (6) mode.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700704
Jiri Pirkoa5499522009-09-25 03:28:09 +0000705primary_reselect
706
707 Specifies the reselection policy for the primary slave. This
708 affects how the primary slave is chosen to become the active slave
709 when failure of the active slave or recovery of the primary slave
710 occurs. This option is designed to prevent flip-flopping between
711 the primary slave and other slaves. Possible values are:
712
713 always or 0 (default)
714
715 The primary slave becomes the active slave whenever it
716 comes back up.
717
718 better or 1
719
720 The primary slave becomes the active slave when it comes
721 back up, if the speed and duplex of the primary slave is
722 better than the speed and duplex of the current active
723 slave.
724
725 failure or 2
726
727 The primary slave becomes the active slave only if the
728 current active slave fails and the primary slave is up.
729
730 The primary_reselect setting is ignored in two cases:
731
732 If no slaves are active, the first slave to recover is
733 made the active slave.
734
735 When initially enslaved, the primary slave is always made
736 the active slave.
737
738 Changing the primary_reselect policy via sysfs will cause an
739 immediate selection of the best active slave according to the new
740 policy. This may or may not result in a change of the active
741 slave, depending upon the circumstances.
742
743 This option was added for bonding version 3.6.0.
744
Mahesh Bandeware9f0fb82014-04-22 16:30:22 -0700745tlb_dynamic_lb
746
747 Specifies if dynamic shuffling of flows is enabled in tlb
748 mode. The value has no effect on any other modes.
749
750 The default behavior of tlb mode is to shuffle active flows across
751 slaves based on the load in that interval. This gives nice lb
752 characteristics but can cause packet reordering. If re-ordering is
753 a concern use this variable to disable flow shuffling and rely on
754 load balancing provided solely by the hash distribution.
755 xmit-hash-policy can be used to select the appropriate hashing for
756 the setup.
757
758 The sysfs entry can be used to change the setting per bond device
759 and the initial value is derived from the module parameter. The
760 sysfs entry is allowed to be changed only if the bond device is
761 down.
762
763 The default value is "1" that enables flow shuffling while value "0"
764 disables it. This option was added in bonding driver 3.7.1
765
766
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767updelay
768
769 Specifies the time, in milliseconds, to wait before enabling a
770 slave after a link recovery has been detected. This option is
771 only valid for the miimon link monitor. The updelay value
772 should be a multiple of the miimon value; if not, it will be
773 rounded down to the nearest multiple. The default value is 0.
774
775use_carrier
776
777 Specifies whether or not miimon should use MII or ETHTOOL
778 ioctls vs. netif_carrier_ok() to determine the link
779 status. The MII or ETHTOOL ioctls are less efficient and
780 utilize a deprecated calling sequence within the kernel. The
781 netif_carrier_ok() relies on the device driver to maintain its
782 state with netif_carrier_on/off; at this writing, most, but
783 not all, device drivers support this facility.
784
785 If bonding insists that the link is up when it should not be,
786 it may be that your network device driver does not support
787 netif_carrier_on/off. The default state for netif_carrier is
788 "carrier on," so if a driver does not support netif_carrier,
789 it will appear as if the link is always up. In this case,
790 setting use_carrier to 0 will cause bonding to revert to the
791 MII / ETHTOOL ioctl method to determine the link state.
792
793 A value of 1 enables the use of netif_carrier_ok(), a value of
794 0 will use the deprecated MII / ETHTOOL ioctls. The default
795 value is 1.
796
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700797xmit_hash_policy
798
799 Selects the transmit hash policy to use for slave selection in
Mahesh Bandewarf05b42e2014-04-22 16:30:20 -0700800 balance-xor, 802.3ad, and tlb modes. Possible values are:
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700801
802 layer2
803
Jianhua Xie92abf752014-07-17 14:16:26 +0800804 Uses XOR of hardware MAC addresses and packet type ID
805 field to generate the hash. The formula is
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700806
Jianhua Xie92abf752014-07-17 14:16:26 +0800807 hash = source MAC XOR destination MAC XOR packet type ID
808 slave number = hash modulo slave count
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700809
810 This algorithm will place all traffic to a particular
811 network peer on the same slave.
812
813 This algorithm is 802.3ad compliant.
814
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800815 layer2+3
816
817 This policy uses a combination of layer2 and layer3
818 protocol information to generate the hash.
819
820 Uses XOR of hardware MAC addresses and IP addresses to
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200821 generate the hash. The formula is
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800822
Jianhua Xie92abf752014-07-17 14:16:26 +0800823 hash = source MAC XOR destination MAC XOR packet type ID
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200824 hash = hash XOR source IP XOR destination IP
825 hash = hash XOR (hash RSHIFT 16)
826 hash = hash XOR (hash RSHIFT 8)
827 And then hash is reduced modulo slave count.
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800828
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200829 If the protocol is IPv6 then the source and destination
830 addresses are first hashed using ipv6_addr_hash.
John Eaglesham6b923cb2012-08-21 20:43:35 +0000831
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800832 This algorithm will place all traffic to a particular
833 network peer on the same slave. For non-IP traffic,
834 the formula is the same as for the layer2 transmit
835 hash policy.
836
837 This policy is intended to provide a more balanced
838 distribution of traffic than layer2 alone, especially
839 in environments where a layer3 gateway device is
840 required to reach most destinations.
841
Matt LaPlanted9195882008-07-25 19:45:33 -0700842 This algorithm is 802.3ad compliant.
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800843
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700844 layer3+4
845
846 This policy uses upper layer protocol information,
847 when available, to generate the hash. This allows for
848 traffic to a particular network peer to span multiple
849 slaves, although a single connection will not span
850 multiple slaves.
851
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200852 The formula for unfragmented TCP and UDP packets is
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700853
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200854 hash = source port, destination port (as in the header)
855 hash = hash XOR source IP XOR destination IP
856 hash = hash XOR (hash RSHIFT 16)
857 hash = hash XOR (hash RSHIFT 8)
858 And then hash is reduced modulo slave count.
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700859
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200860 If the protocol is IPv6 then the source and destination
861 addresses are first hashed using ipv6_addr_hash.
John Eaglesham6b923cb2012-08-21 20:43:35 +0000862
863 For fragmented TCP or UDP packets and all other IPv4 and
864 IPv6 protocol traffic, the source and destination port
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700865 information is omitted. For non-IP traffic, the
866 formula is the same as for the layer2 transmit hash
867 policy.
868
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700869 This algorithm is not fully 802.3ad compliant. A
870 single TCP or UDP conversation containing both
871 fragmented and unfragmented packets will see packets
872 striped across two interfaces. This may result in out
873 of order delivery. Most traffic types will not meet
874 this criteria, as TCP rarely fragments traffic, and
875 most UDP traffic is not involved in extended
876 conversations. Other implementations of 802.3ad may
877 or may not tolerate this noncompliance.
878
Nikolay Aleksandrov7a6afab2013-10-02 13:39:26 +0200879 encap2+3
880
881 This policy uses the same formula as layer2+3 but it
882 relies on skb_flow_dissect to obtain the header fields
883 which might result in the use of inner headers if an
884 encapsulation protocol is used. For example this will
885 improve the performance for tunnel users because the
886 packets will be distributed according to the encapsulated
887 flows.
888
889 encap3+4
890
891 This policy uses the same formula as layer3+4 but it
892 relies on skb_flow_dissect to obtain the header fields
893 which might result in the use of inner headers if an
894 encapsulation protocol is used. For example this will
895 improve the performance for tunnel users because the
896 packets will be distributed according to the encapsulated
897 flows.
898
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700899 The default value is layer2. This option was added in bonding
Jay Vosburgh6f6652b2007-12-06 23:40:34 -0800900 version 2.6.3. In earlier versions of bonding, this parameter
901 does not exist, and the layer2 policy is the only policy. The
902 layer2+3 value was added for bonding version 3.2.2.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903
Flavio Leitnerc2952c32010-10-05 14:23:59 +0000904resend_igmp
905
906 Specifies the number of IGMP membership reports to be issued after
907 a failover event. One membership report is issued immediately after
908 the failover, subsequent packets are sent in each 200ms interval.
909
Flavio Leitner94265cf2011-05-25 08:38:58 +0000910 The valid range is 0 - 255; the default value is 1. A value of 0
911 prevents the IGMP membership report from being issued in response
912 to the failover event.
913
914 This option is useful for bonding modes balance-rr (0), active-backup
915 (1), balance-tlb (5) and balance-alb (6), in which a failover can
916 switch the IGMP traffic from one slave to another. Therefore a fresh
917 IGMP report must be issued to cause the switch to forward the incoming
918 IGMP traffic over the newly selected slave.
919
920 This option was added for bonding version 3.7.0.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700921
dingtianhong84a6a0a2013-12-21 14:40:22 +0800922lp_interval
923
924 Specifies the number of seconds between instances where the bonding
925 driver sends learning packets to each slaves peer switch.
926
927 The valid range is 1 - 0x7fffffff; the default value is 1. This Option
928 has effect only in balance-tlb and balance-alb modes.
929
Linus Torvalds1da177e2005-04-16 15:20:36 -07009303. Configuring Bonding Devices
931==============================
932
Auke Kok6224e012006-06-08 11:15:35 -0700933 You can configure bonding using either your distro's network
Cong Wangb1098bb2013-05-27 15:49:16 +0000934initialization scripts, or manually using either iproute2 or the
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000935sysfs interface. Distros generally use one of three packages for the
936network initialization scripts: initscripts, sysconfig or interfaces.
937Recent versions of these packages have support for bonding, while older
Auke Kok6224e012006-06-08 11:15:35 -0700938versions do not.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700939
940 We will first describe the options for configuring bonding for
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000941distros using versions of initscripts, sysconfig and interfaces with full
942or partial support for bonding, then provide information on enabling
Linus Torvalds1da177e2005-04-16 15:20:36 -0700943bonding without support from the network initialization scripts (i.e.,
944older versions of initscripts or sysconfig).
945
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000946 If you're unsure whether your distro uses sysconfig,
947initscripts or interfaces, or don't know if it's new enough, have no fear.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948Determining this is fairly straightforward.
949
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +0000950 First, look for a file called interfaces in /etc/network directory.
951If this file is present in your system, then your system use interfaces. See
952Configuration with Interfaces Support.
953
954 Else, issue the command:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955
956$ rpm -qf /sbin/ifup
957
958 It will respond with a line of text starting with either
959"initscripts" or "sysconfig," followed by some numbers. This is the
960package that provides your network initialization scripts.
961
962 Next, to determine if your installation supports bonding,
963issue the command:
964
965$ grep ifenslave /sbin/ifup
966
967 If this returns any matches, then your initscripts or
968sysconfig has support for bonding.
969
Auke Kok6224e012006-06-08 11:15:35 -07009703.1 Configuration with Sysconfig Support
Linus Torvalds1da177e2005-04-16 15:20:36 -0700971----------------------------------------
972
973 This section applies to distros using a version of sysconfig
974with bonding support, for example, SuSE Linux Enterprise Server 9.
975
976 SuSE SLES 9's networking configuration system does support
977bonding, however, at this writing, the YaST system configuration
Auke Kok6224e012006-06-08 11:15:35 -0700978front end does not provide any means to work with bonding devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700979Bonding devices can be managed by hand, however, as follows.
980
981 First, if they have not already been configured, configure the
982slave devices. On SLES 9, this is most easily done by running the
983yast2 sysconfig configuration utility. The goal is for to create an
984ifcfg-id file for each slave device. The simplest way to accomplish
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700985this is to configure the devices for DHCP (this is only to get the
986file ifcfg-id file created; see below for some issues with DHCP). The
987name of the configuration file for each device will be of the form:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700988
989ifcfg-id-xx:xx:xx:xx:xx:xx
990
991 Where the "xx" portion will be replaced with the digits from
992the device's permanent MAC address.
993
994 Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been
995created, it is necessary to edit the configuration files for the slave
996devices (the MAC addresses correspond to those of the slave devices).
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700997Before editing, the file will contain multiple lines, and will look
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998something like this:
999
1000BOOTPROTO='dhcp'
1001STARTMODE='on'
1002USERCTL='no'
1003UNIQUE='XNzu.WeZGOGF+4wE'
1004_nm_name='bus-pci-0001:61:01.0'
1005
1006 Change the BOOTPROTO and STARTMODE lines to the following:
1007
1008BOOTPROTO='none'
1009STARTMODE='off'
1010
1011 Do not alter the UNIQUE or _nm_name lines. Remove any other
1012lines (USERCTL, etc).
1013
1014 Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified,
1015it's time to create the configuration file for the bonding device
1016itself. This file is named ifcfg-bondX, where X is the number of the
1017bonding device to create, starting at 0. The first such file is
1018ifcfg-bond0, the second is ifcfg-bond1, and so on. The sysconfig
1019network configuration system will correctly start multiple instances
1020of bonding.
1021
1022 The contents of the ifcfg-bondX file is as follows:
1023
1024BOOTPROTO="static"
1025BROADCAST="10.0.2.255"
1026IPADDR="10.0.2.10"
1027NETMASK="255.255.0.0"
1028NETWORK="10.0.2.0"
1029REMOTE_IPADDR=""
1030STARTMODE="onboot"
1031BONDING_MASTER="yes"
1032BONDING_MODULE_OPTS="mode=active-backup miimon=100"
1033BONDING_SLAVE0="eth0"
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001034BONDING_SLAVE1="bus-pci-0000:06:08.1"
Linus Torvalds1da177e2005-04-16 15:20:36 -07001035
1036 Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK
1037values with the appropriate values for your network.
1038
Linus Torvalds1da177e2005-04-16 15:20:36 -07001039 The STARTMODE specifies when the device is brought online.
1040The possible values are:
1041
1042 onboot: The device is started at boot time. If you're not
1043 sure, this is probably what you want.
1044
1045 manual: The device is started only when ifup is called
1046 manually. Bonding devices may be configured this
1047 way if you do not wish them to start automatically
1048 at boot for some reason.
1049
1050 hotplug: The device is started by a hotplug event. This is not
1051 a valid choice for a bonding device.
1052
1053 off or ignore: The device configuration is ignored.
1054
1055 The line BONDING_MASTER='yes' indicates that the device is a
1056bonding master device. The only useful value is "yes."
1057
1058 The contents of BONDING_MODULE_OPTS are supplied to the
1059instance of the bonding module for this device. Specify the options
1060for the bonding mode, link monitoring, and so on here. Do not include
1061the max_bonds bonding parameter; this will confuse the configuration
1062system if you have multiple bonding devices.
1063
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001064 Finally, supply one BONDING_SLAVEn="slave device" for each
1065slave. where "n" is an increasing value, one for each slave. The
1066"slave device" is either an interface name, e.g., "eth0", or a device
1067specifier for the network device. The interface name is easier to
1068find, but the ethN names are subject to change at boot time if, e.g.,
1069a device early in the sequence has failed. The device specifiers
1070(bus-pci-0000:06:08.1 in the example above) specify the physical
1071network device, and will not change unless the device's bus location
1072changes (for example, it is moved from one PCI slot to another). The
1073example above uses one of each type for demonstration purposes; most
1074configurations will choose one or the other for all slave devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001075
1076 When all configuration files have been modified or created,
1077networking must be restarted for the configuration changes to take
1078effect. This can be accomplished via the following:
1079
1080# /etc/init.d/network restart
1081
1082 Note that the network control script (/sbin/ifdown) will
1083remove the bonding module as part of the network shutdown processing,
1084so it is not necessary to remove the module by hand if, e.g., the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001085module parameters have changed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001086
1087 Also, at this writing, YaST/YaST2 will not manage bonding
1088devices (they do not show bonding interfaces on its list of network
1089devices). It is necessary to edit the configuration file by hand to
1090change the bonding configuration.
1091
1092 Additional general options and details of the ifcfg file
1093format can be found in an example ifcfg template file:
1094
1095/etc/sysconfig/network/ifcfg.template
1096
1097 Note that the template does not document the various BONDING_
1098settings described above, but does describe many of the other options.
1099
Auke Kok6224e012006-06-08 11:15:35 -070011003.1.1 Using DHCP with Sysconfig
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001101-------------------------------
1102
1103 Under sysconfig, configuring a device with BOOTPROTO='dhcp'
1104will cause it to query DHCP for its IP address information. At this
1105writing, this does not function for bonding devices; the scripts
1106attempt to obtain the device address from DHCP prior to adding any of
1107the slave devices. Without active slaves, the DHCP requests are not
1108sent to the network.
1109
Auke Kok6224e012006-06-08 11:15:35 -070011103.1.2 Configuring Multiple Bonds with Sysconfig
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001111-----------------------------------------------
1112
1113 The sysconfig network initialization system is capable of
1114handling multiple bonding devices. All that is necessary is for each
1115bonding instance to have an appropriately configured ifcfg-bondX file
1116(as described above). Do not specify the "max_bonds" parameter to any
1117instance of bonding, as this will confuse sysconfig. If you require
1118multiple bonding devices with identical parameters, create multiple
1119ifcfg-bondX files.
1120
1121 Because the sysconfig scripts supply the bonding module
1122options in the ifcfg-bondX file, it is not necessary to add them to
Lucas De Marchi970e2482012-03-30 13:37:16 -07001123the system /etc/modules.d/*.conf configuration files.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001124
Auke Kok6224e012006-06-08 11:15:35 -070011253.2 Configuration with Initscripts Support
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126------------------------------------------
1127
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001128 This section applies to distros using a recent version of
1129initscripts with bonding support, for example, Red Hat Enterprise Linux
1130version 3 or later, Fedora, etc. On these systems, the network
1131initialization scripts have knowledge of bonding, and can be configured to
1132control bonding devices. Note that older versions of the initscripts
1133package have lower levels of support for bonding; this will be noted where
1134applicable.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001135
1136 These distros will not automatically load the network adapter
1137driver unless the ethX device is configured with an IP address.
1138Because of this constraint, users must manually configure a
1139network-script file for all physical adapters that will be members of
1140a bondX link. Network script files are located in the directory:
1141
1142/etc/sysconfig/network-scripts
1143
1144 The file name must be prefixed with "ifcfg-eth" and suffixed
1145with the adapter's physical adapter number. For example, the script
1146for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0.
1147Place the following text in the file:
1148
1149DEVICE=eth0
1150USERCTL=no
1151ONBOOT=yes
1152MASTER=bond0
1153SLAVE=yes
1154BOOTPROTO=none
1155
1156 The DEVICE= line will be different for every ethX device and
1157must correspond with the name of the file, i.e., ifcfg-eth1 must have
1158a device line of DEVICE=eth1. The setting of the MASTER= line will
1159also depend on the final bonding interface name chosen for your bond.
1160As with other network devices, these typically start at 0, and go up
1161one for each device, i.e., the first bonding instance is bond0, the
1162second is bond1, and so on.
1163
1164 Next, create a bond network script. The file name for this
1165script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is
1166the number of the bond. For bond0 the file is named "ifcfg-bond0",
1167for bond1 it is named "ifcfg-bond1", and so on. Within that file,
1168place the following text:
1169
1170DEVICE=bond0
1171IPADDR=192.168.1.1
1172NETMASK=255.255.255.0
1173NETWORK=192.168.1.0
1174BROADCAST=192.168.1.255
1175ONBOOT=yes
1176BOOTPROTO=none
1177USERCTL=no
1178
1179 Be sure to change the networking specific lines (IPADDR,
1180NETMASK, NETWORK and BROADCAST) to match your network configuration.
1181
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001182 For later versions of initscripts, such as that found with Fedora
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +000011837 (or later) and Red Hat Enterprise Linux version 5 (or later), it is possible,
1184and, indeed, preferable, to specify the bonding options in the ifcfg-bond0
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001185file, e.g. a line of the format:
1186
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001187BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=192.168.1.254"
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001188
1189 will configure the bond with the specified options. The options
1190specified in BONDING_OPTS are identical to the bonding module parameters
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001191except for the arp_ip_target field when using versions of initscripts older
1192than and 8.57 (Fedora 8) and 8.45.19 (Red Hat Enterprise Linux 5.2). When
1193using older versions each target should be included as a separate option and
1194should be preceded by a '+' to indicate it should be added to the list of
1195queried targets, e.g.,
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001196
1197 arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2
1198
1199 is the proper syntax to specify multiple targets. When specifying
Lucas De Marchi970e2482012-03-30 13:37:16 -07001200options via BONDING_OPTS, it is not necessary to edit /etc/modprobe.d/*.conf.
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001201
Andy Gospodarek3f8b4b12008-10-22 11:19:48 +00001202 For even older versions of initscripts that do not support
Lucas De Marchi970e2482012-03-30 13:37:16 -07001203BONDING_OPTS, it is necessary to edit /etc/modprobe.d/*.conf, depending upon
1204your distro) to load the bonding module with your desired options when the
1205bond0 interface is brought up. The following lines in /etc/modprobe.d/*.conf
1206will load the bonding module, and select its options:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001207
1208alias bond0 bonding
1209options bond0 mode=balance-alb miimon=100
1210
1211 Replace the sample parameters with the appropriate set of
1212options for your configuration.
1213
1214 Finally run "/etc/rc.d/init.d/network restart" as root. This
1215will restart the networking subsystem and your bond link should be now
1216up and running.
1217
Auke Kok6224e012006-06-08 11:15:35 -070012183.2.1 Using DHCP with Initscripts
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001219---------------------------------
1220
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001221 Recent versions of initscripts (the versions supplied with Fedora
1222Core 3 and Red Hat Enterprise Linux 4, or later versions, are reported to
1223work) have support for assigning IP information to bonding devices via
1224DHCP.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001225
1226 To configure bonding for DHCP, configure it as described
1227above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp"
1228and add a line consisting of "TYPE=Bonding". Note that the TYPE value
1229is case sensitive.
1230
Auke Kok6224e012006-06-08 11:15:35 -070012313.2.2 Configuring Multiple Bonds with Initscripts
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001232-------------------------------------------------
1233
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001234 Initscripts packages that are included with Fedora 7 and Red Hat
1235Enterprise Linux 5 support multiple bonding interfaces by simply
1236specifying the appropriate BONDING_OPTS= in ifcfg-bondX where X is the
1237number of the bond. This support requires sysfs support in the kernel,
1238and a bonding driver of version 3.0.0 or later. Other configurations may
1239not support this method for specifying multiple bonding interfaces; for
1240those instances, see the "Configuring Multiple Bonds Manually" section,
1241below.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001242
Cong Wangb1098bb2013-05-27 15:49:16 +000012433.3 Configuring Bonding Manually with iproute2
Auke Kok6224e012006-06-08 11:15:35 -07001244-----------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245
1246 This section applies to distros whose network initialization
1247scripts (the sysconfig or initscripts package) do not have specific
1248knowledge of bonding. One such distro is SuSE Linux Enterprise Server
1249version 8.
1250
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001251 The general method for these systems is to place the bonding
Lucas De Marchi970e2482012-03-30 13:37:16 -07001252module parameters into a config file in /etc/modprobe.d/ (as
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001253appropriate for the installed distro), then add modprobe and/or
Cong Wangb1098bb2013-05-27 15:49:16 +00001254`ip link` commands to the system's global init script. The name of
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001255the global init script differs; for sysconfig, it is
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256/etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local.
1257
1258 For example, if you wanted to make a simple bond of two e100
1259devices (presumed to be eth0 and eth1), and have it persist across
1260reboots, edit the appropriate file (/etc/init.d/boot.local or
1261/etc/rc.d/rc.local), and add the following:
1262
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001263modprobe bonding mode=balance-alb miimon=100
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264modprobe e100
1265ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
Cong Wangb1098bb2013-05-27 15:49:16 +00001266ip link set eth0 master bond0
1267ip link set eth1 master bond0
Linus Torvalds1da177e2005-04-16 15:20:36 -07001268
1269 Replace the example bonding module parameters and bond0
1270network configuration (IP address, netmask, etc) with the appropriate
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001271values for your configuration.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001272
1273 Unfortunately, this method will not provide support for the
1274ifup and ifdown scripts on the bond devices. To reload the bonding
1275configuration, it is necessary to run the initialization script, e.g.,
1276
1277# /etc/init.d/boot.local
1278
1279 or
1280
1281# /etc/rc.d/rc.local
1282
1283 It may be desirable in such a case to create a separate script
1284which only initializes the bonding configuration, then call that
1285separate script from within boot.local. This allows for bonding to be
1286enabled without re-running the entire global init script.
1287
1288 To shut down the bonding devices, it is necessary to first
1289mark the bonding device itself as being down, then remove the
1290appropriate device driver modules. For our example above, you can do
1291the following:
1292
1293# ifconfig bond0 down
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001294# rmmod bonding
Linus Torvalds1da177e2005-04-16 15:20:36 -07001295# rmmod e100
1296
1297 Again, for convenience, it may be desirable to create a script
1298with these commands.
1299
1300
Jay Vosburgh00354cf2005-07-21 12:18:02 -070013013.3.1 Configuring Multiple Bonds Manually
1302-----------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001303
1304 This section contains information on configuring multiple
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001305bonding devices with differing options for those systems whose network
1306initialization scripts lack support for configuring multiple bonds.
1307
1308 If you require multiple bonding devices, but all with the same
1309options, you may wish to use the "max_bonds" module parameter,
1310documented above.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001311
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001312 To create multiple bonding devices with differing options, it is
Rick Jonesf8b72d32012-07-20 10:51:37 +00001313preferable to use bonding parameters exported by sysfs, documented in the
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001314section below.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001316 For versions of bonding without sysfs support, the only means to
1317provide multiple instances of bonding with differing options is to load
1318the bonding driver multiple times. Note that current versions of the
1319sysconfig network initialization scripts handle this automatically; if
1320your distro uses these scripts, no special action is needed. See the
1321section Configuring Bonding Devices, above, if you're not sure about your
1322network initialization scripts.
1323
1324 To load multiple instances of the module, it is necessary to
1325specify a different name for each instance (the module loading system
1326requires that every loaded module, even multiple instances of the same
1327module, have a unique name). This is accomplished by supplying multiple
Lucas De Marchi970e2482012-03-30 13:37:16 -07001328sets of bonding options in /etc/modprobe.d/*.conf, for example:
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001329
1330alias bond0 bonding
1331options bond0 -o bond0 mode=balance-rr miimon=100
1332
1333alias bond1 bonding
1334options bond1 -o bond1 mode=balance-alb miimon=50
1335
1336 will load the bonding module two times. The first instance is
1337named "bond0" and creates the bond0 device in balance-rr mode with an
1338miimon of 100. The second instance is named "bond1" and creates the
1339bond1 device in balance-alb mode with an miimon of 50.
1340
1341 In some circumstances (typically with older distributions),
1342the above does not work, and the second bonding instance never sees
1343its options. In that case, the second options line can be substituted
1344as follows:
1345
1346install bond1 /sbin/modprobe --ignore-install bonding -o bond1 \
1347 mode=balance-alb miimon=50
1348
1349 This may be repeated any number of times, specifying a new and
1350unique name in place of bond1 for each subsequent instance.
1351
1352 It has been observed that some Red Hat supplied kernels are unable
1353to rename modules at load time (the "-o bond1" part). Attempts to pass
1354that option to modprobe will produce an "Operation not permitted" error.
1355This has been reported on some Fedora Core kernels, and has been seen on
1356RHEL 4 as well. On kernels exhibiting this problem, it will be impossible
1357to configure multiple bonds with differing parameters (as they are older
1358kernels, and also lack sysfs support).
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001359
Auke Kok6224e012006-06-08 11:15:35 -070013603.4 Configuring Bonding Manually via Sysfs
1361------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08001363 Starting with version 3.0.0, Channel Bonding may be configured
Auke Kok6224e012006-06-08 11:15:35 -07001364via the sysfs interface. This interface allows dynamic configuration
1365of all bonds in the system without unloading the module. It also
1366allows for adding and removing bonds at runtime. Ifenslave is no
1367longer required, though it is still supported.
1368
1369 Use of the sysfs interface allows you to use multiple bonds
1370with different configurations without having to reload the module.
1371It also allows you to use multiple, differently configured bonds when
1372bonding is compiled into the kernel.
1373
1374 You must have the sysfs filesystem mounted to configure
1375bonding this way. The examples in this document assume that you
1376are using the standard mount point for sysfs, e.g. /sys. If your
1377sysfs filesystem is mounted elsewhere, you will need to adjust the
1378example paths accordingly.
1379
1380Creating and Destroying Bonds
1381-----------------------------
1382To add a new bond foo:
1383# echo +foo > /sys/class/net/bonding_masters
1384
1385To remove an existing bond bar:
1386# echo -bar > /sys/class/net/bonding_masters
1387
1388To show all existing bonds:
1389# cat /sys/class/net/bonding_masters
1390
1391NOTE: due to 4K size limitation of sysfs files, this list may be
1392truncated if you have more than a few hundred bonds. This is unlikely
1393to occur under normal operating conditions.
1394
1395Adding and Removing Slaves
1396--------------------------
1397 Interfaces may be enslaved to a bond using the file
1398/sys/class/net/<bond>/bonding/slaves. The semantics for this file
1399are the same as for the bonding_masters file.
1400
1401To enslave interface eth0 to bond bond0:
1402# ifconfig bond0 up
1403# echo +eth0 > /sys/class/net/bond0/bonding/slaves
1404
1405To free slave eth0 from bond bond0:
1406# echo -eth0 > /sys/class/net/bond0/bonding/slaves
1407
Auke Kok6224e012006-06-08 11:15:35 -07001408 When an interface is enslaved to a bond, symlinks between the
1409two are created in the sysfs filesystem. In this case, you would get
1410/sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and
1411/sys/class/net/eth0/master pointing to /sys/class/net/bond0.
1412
1413 This means that you can tell quickly whether or not an
1414interface is enslaved by looking for the master symlink. Thus:
1415# echo -eth0 > /sys/class/net/eth0/master/bonding/slaves
1416will free eth0 from whatever bond it is enslaved to, regardless of
1417the name of the bond interface.
1418
1419Changing a Bond's Configuration
1420-------------------------------
1421 Each bond may be configured individually by manipulating the
1422files located in /sys/class/net/<bond name>/bonding
1423
1424 The names of these files correspond directly with the command-
Paolo Ornati670e9f32006-10-03 22:57:56 +02001425line parameters described elsewhere in this file, and, with the
Auke Kok6224e012006-06-08 11:15:35 -07001426exception of arp_ip_target, they accept the same values. To see the
1427current setting, simply cat the appropriate file.
1428
1429 A few examples will be given here; for specific usage
1430guidelines for each parameter, see the appropriate section in this
1431document.
1432
1433To configure bond0 for balance-alb mode:
1434# ifconfig bond0 down
1435# echo 6 > /sys/class/net/bond0/bonding/mode
1436 - or -
1437# echo balance-alb > /sys/class/net/bond0/bonding/mode
1438 NOTE: The bond interface must be down before the mode can be
1439changed.
1440
1441To enable MII monitoring on bond0 with a 1 second interval:
1442# echo 1000 > /sys/class/net/bond0/bonding/miimon
1443 NOTE: If ARP monitoring is enabled, it will disabled when MII
1444monitoring is enabled, and vice-versa.
1445
1446To add ARP targets:
1447# echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
1448# echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target
Brian Haley5a31bec2009-04-13 00:11:30 -07001449 NOTE: up to 16 target addresses may be specified.
Auke Kok6224e012006-06-08 11:15:35 -07001450
1451To remove an ARP target:
1452# echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
1453
Neil Horman7eacd032013-09-13 11:05:33 -04001454To configure the interval between learning packet transmits:
1455# echo 12 > /sys/class/net/bond0/bonding/lp_interval
1456 NOTE: the lp_inteval is the number of seconds between instances where
1457the bonding driver sends learning packets to each slaves peer switch. The
1458default interval is 1 second.
1459
Auke Kok6224e012006-06-08 11:15:35 -07001460Example Configuration
1461---------------------
1462 We begin with the same example that is shown in section 3.3,
1463executed with sysfs, and without using ifenslave.
1464
1465 To make a simple bond of two e100 devices (presumed to be eth0
1466and eth1), and have it persist across reboots, edit the appropriate
1467file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the
1468following:
1469
1470modprobe bonding
1471modprobe e100
1472echo balance-alb > /sys/class/net/bond0/bonding/mode
1473ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
1474echo 100 > /sys/class/net/bond0/bonding/miimon
1475echo +eth0 > /sys/class/net/bond0/bonding/slaves
1476echo +eth1 > /sys/class/net/bond0/bonding/slaves
1477
1478 To add a second bond, with two e1000 interfaces in
1479active-backup mode, using ARP monitoring, add the following lines to
1480your init script:
1481
1482modprobe e1000
1483echo +bond1 > /sys/class/net/bonding_masters
1484echo active-backup > /sys/class/net/bond1/bonding/mode
1485ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up
1486echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target
1487echo 2000 > /sys/class/net/bond1/bonding/arp_interval
1488echo +eth2 > /sys/class/net/bond1/bonding/slaves
1489echo +eth3 > /sys/class/net/bond1/bonding/slaves
1490
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +000014913.5 Configuration with Interfaces Support
1492-----------------------------------------
1493
1494 This section applies to distros which use /etc/network/interfaces file
1495to describe network interface configuration, most notably Debian and it's
1496derivatives.
1497
1498 The ifup and ifdown commands on Debian don't support bonding out of
1499the box. The ifenslave-2.6 package should be installed to provide bonding
1500support. Once installed, this package will provide bond-* options to be used
1501into /etc/network/interfaces.
1502
1503 Note that ifenslave-2.6 package will load the bonding module and use
1504the ifenslave command when appropriate.
1505
1506Example Configurations
1507----------------------
1508
1509In /etc/network/interfaces, the following stanza will configure bond0, in
1510active-backup mode, with eth0 and eth1 as slaves.
1511
1512auto bond0
1513iface bond0 inet dhcp
1514 bond-slaves eth0 eth1
1515 bond-mode active-backup
1516 bond-miimon 100
1517 bond-primary eth0 eth1
1518
1519If the above configuration doesn't work, you might have a system using
1520upstart for system startup. This is most notably true for recent
1521Ubuntu versions. The following stanza in /etc/network/interfaces will
1522produce the same result on those systems.
1523
1524auto bond0
1525iface bond0 inet dhcp
1526 bond-slaves none
1527 bond-mode active-backup
1528 bond-miimon 100
1529
1530auto eth0
1531iface eth0 inet manual
1532 bond-master bond0
1533 bond-primary eth0 eth1
1534
1535auto eth1
1536iface eth1 inet manual
1537 bond-master bond0
1538 bond-primary eth0 eth1
1539
1540For a full list of bond-* supported options in /etc/network/interfaces and some
1541more advanced examples tailored to you particular distros, see the files in
1542/usr/share/doc/ifenslave-2.6.
1543
15443.6 Overriding Configuration for Special Cases
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001545----------------------------------------------
Nicolas de Pesloüande221bd2011-01-24 13:21:37 +00001546
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001547When using the bonding driver, the physical port which transmits a frame is
1548typically selected by the bonding driver, and is not relevant to the user or
1549system administrator. The output port is simply selected using the policies of
1550the selected bonding mode. On occasion however, it is helpful to direct certain
1551classes of traffic to certain physical interfaces on output to implement
1552slightly more complex policies. For example, to reach a web server over a
1553bonded interface in which eth0 connects to a private network, while eth1
1554connects via a public network, it may be desirous to bias the bond to send said
1555traffic over eth0 first, using eth1 only as a fall back, while all other traffic
1556can safely be sent over either interface. Such configurations may be achieved
1557using the traffic control utilities inherent in linux.
Auke Kok6224e012006-06-08 11:15:35 -07001558
Andy Gospodarekbb1d9122010-06-02 08:40:18 +00001559By default the bonding driver is multiqueue aware and 16 queues are created
1560when the driver initializes (see Documentation/networking/multiqueue.txt
1561for details). If more or less queues are desired the module parameter
1562tx_queues can be used to change this value. There is no sysfs parameter
1563available as the allocation is done at module init time.
1564
1565The output of the file /proc/net/bonding/bondX has changed so the output Queue
1566ID is now printed for each slave:
1567
1568Bonding Mode: fault-tolerance (active-backup)
1569Primary Slave: None
1570Currently Active Slave: eth0
1571MII Status: up
1572MII Polling Interval (ms): 0
1573Up Delay (ms): 0
1574Down Delay (ms): 0
1575
1576Slave Interface: eth0
1577MII Status: up
1578Link Failure Count: 0
1579Permanent HW addr: 00:1a:a0:12:8f:cb
1580Slave queue ID: 0
1581
1582Slave Interface: eth1
1583MII Status: up
1584Link Failure Count: 0
1585Permanent HW addr: 00:1a:a0:12:8f:cc
1586Slave queue ID: 2
1587
1588The queue_id for a slave can be set using the command:
1589
1590# echo "eth1:2" > /sys/class/net/bond0/bonding/queue_id
1591
1592Any interface that needs a queue_id set should set it with multiple calls
1593like the one above until proper priorities are set for all interfaces. On
1594distributions that allow configuration via initscripts, multiple 'queue_id'
1595arguments can be added to BONDING_OPTS to set all needed slave queues.
1596
1597These queue id's can be used in conjunction with the tc utility to configure
1598a multiqueue qdisc and filters to bias certain traffic to transmit on certain
1599slave devices. For instance, say we wanted, in the above configuration to
1600force all traffic bound to 192.168.1.100 to use eth1 in the bond as its output
1601device. The following commands would accomplish this:
1602
1603# tc qdisc add dev bond0 handle 1 root multiq
1604
1605# tc filter add dev bond0 protocol ip parent 1: prio 1 u32 match ip dst \
1606 192.168.1.100 action skbedit queue_mapping 2
1607
1608These commands tell the kernel to attach a multiqueue queue discipline to the
1609bond0 interface and filter traffic enqueued to it, such that packets with a dst
1610ip of 192.168.1.100 have their output queue mapping value overwritten to 2.
1611This value is then passed into the driver, causing the normal output path
1612selection policy to be overridden, selecting instead qid 2, which maps to eth1.
1613
1614Note that qid values begin at 1. Qid 0 is reserved to initiate to the driver
1615that normal output policy selection should take place. One benefit to simply
1616leaving the qid for a slave to 0 is the multiqueue awareness in the bonding
1617driver that is now present. This awareness allows tc filters to be placed on
1618slave devices as well as bond devices and the bonding driver will simply act as
1619a pass-through for selecting output queues on the slave device rather than
1620output port selection.
1621
1622This feature first appeared in bonding driver version 3.7.0 and support for
1623output slave selection was limited to round-robin and active-backup modes.
1624
16254 Querying Bonding Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626=================================
1627
Auke Kok6224e012006-06-08 11:15:35 -070016284.1 Bonding Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629-------------------------
1630
1631 Each bonding device has a read-only file residing in the
1632/proc/net/bonding directory. The file contents include information
1633about the bonding configuration, options and state of each slave.
1634
1635 For example, the contents of /proc/net/bonding/bond0 after the
1636driver is loaded with parameters of mode=0 and miimon=1000 is
1637generally as follows:
1638
1639 Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004)
1640 Bonding Mode: load balancing (round-robin)
1641 Currently Active Slave: eth0
1642 MII Status: up
1643 MII Polling Interval (ms): 1000
1644 Up Delay (ms): 0
1645 Down Delay (ms): 0
1646
1647 Slave Interface: eth1
1648 MII Status: up
1649 Link Failure Count: 1
1650
1651 Slave Interface: eth0
1652 MII Status: up
1653 Link Failure Count: 1
1654
1655 The precise format and contents will change depending upon the
1656bonding configuration, state, and version of the bonding driver.
1657
Auke Kok6224e012006-06-08 11:15:35 -070016584.2 Network configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659-------------------------
1660
1661 The network configuration can be inspected using the ifconfig
1662command. Bonding devices will have the MASTER flag set; Bonding slave
1663devices will have the SLAVE flag set. The ifconfig output does not
1664contain information on which slaves are associated with which masters.
1665
1666 In the example below, the bond0 interface is the master
1667(MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of
1668bond0 have the same MAC address (HWaddr) as bond0 for all modes except
1669TLB and ALB that require a unique MAC address for each slave.
1670
1671# /sbin/ifconfig
1672bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
1673 inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0
1674 UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1
1675 RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0
1676 TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0
1677 collisions:0 txqueuelen:0
1678
1679eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
Linus Torvalds1da177e2005-04-16 15:20:36 -07001680 UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
1681 RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0
1682 TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0
1683 collisions:0 txqueuelen:100
1684 Interrupt:10 Base address:0x1080
1685
1686eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4
Linus Torvalds1da177e2005-04-16 15:20:36 -07001687 UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1
1688 RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0
1689 TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0
1690 collisions:0 txqueuelen:100
1691 Interrupt:9 Base address:0x1400
1692
Auke Kok6224e012006-06-08 11:15:35 -070016935. Switch Configuration
Linus Torvalds1da177e2005-04-16 15:20:36 -07001694=======================
1695
1696 For this section, "switch" refers to whatever system the
1697bonded devices are directly connected to (i.e., where the other end of
1698the cable plugs into). This may be an actual dedicated switch device,
1699or it may be another regular system (e.g., another computer running
1700Linux),
1701
1702 The active-backup, balance-tlb and balance-alb modes do not
1703require any specific configuration of the switch.
1704
1705 The 802.3ad mode requires that the switch have the appropriate
1706ports configured as an 802.3ad aggregation. The precise method used
1707to configure this varies from switch to switch, but, for example, a
1708Cisco 3550 series switch requires that the appropriate ports first be
1709grouped together in a single etherchannel instance, then that
1710etherchannel is set to mode "lacp" to enable 802.3ad (instead of
1711standard EtherChannel).
1712
1713 The balance-rr, balance-xor and broadcast modes generally
1714require that the switch have the appropriate ports grouped together.
1715The nomenclature for such a group differs between switches, it may be
1716called an "etherchannel" (as in the Cisco example, above), a "trunk
1717group" or some other similar variation. For these modes, each switch
1718will also have its own configuration options for the switch's transmit
1719policy to the bond. Typical choices include XOR of either the MAC or
1720IP addresses. The transmit policy of the two peers does not need to
1721match. For these three modes, the bonding mode really selects a
1722transmit policy for an EtherChannel group; all three will interoperate
1723with another EtherChannel group.
1724
1725
Auke Kok6224e012006-06-08 11:15:35 -070017266. 802.1q VLAN Support
Linus Torvalds1da177e2005-04-16 15:20:36 -07001727======================
1728
1729 It is possible to configure VLAN devices over a bond interface
1730using the 8021q driver. However, only packets coming from the 8021q
1731driver and passing through bonding will be tagged by default. Self
1732generated packets, for example, bonding's learning packets or ARP
1733packets generated by either ALB mode or the ARP monitor mechanism, are
1734tagged internally by bonding itself. As a result, bonding must
1735"learn" the VLAN IDs configured above it, and use those IDs to tag
1736self generated packets.
1737
1738 For reasons of simplicity, and to support the use of adapters
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001739that can do VLAN hardware acceleration offloading, the bonding
1740interface declares itself as fully hardware offloading capable, it gets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001741the add_vid/kill_vid notifications to gather the necessary
1742information, and it propagates those actions to the slaves. In case
1743of mixed adapter types, hardware accelerated tagged packets that
1744should go through an adapter that is not offloading capable are
1745"un-accelerated" by the bonding driver so the VLAN tag sits in the
1746regular location.
1747
1748 VLAN interfaces *must* be added on top of a bonding interface
1749only after enslaving at least one slave. The bonding interface has a
1750hardware address of 00:00:00:00:00:00 until the first slave is added.
1751If the VLAN interface is created prior to the first enslavement, it
1752would pick up the all-zeroes hardware address. Once the first slave
1753is attached to the bond, the bond device itself will pick up the
1754slave's hardware address, which is then available for the VLAN device.
1755
1756 Also, be aware that a similar problem can occur if all slaves
1757are released from a bond that still has one or more VLAN interfaces on
1758top of it. When a new slave is added, the bonding interface will
1759obtain its hardware address from the first slave, which might not
1760match the hardware address of the VLAN interfaces (which was
1761ultimately copied from an earlier slave).
1762
1763 There are two methods to insure that the VLAN device operates
1764with the correct hardware address if all slaves are removed from a
1765bond interface:
1766
1767 1. Remove all VLAN interfaces then recreate them
1768
1769 2. Set the bonding interface's hardware address so that it
1770matches the hardware address of the VLAN interfaces.
1771
1772 Note that changing a VLAN interface's HW address would set the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001773underlying device -- i.e. the bonding interface -- to promiscuous
Linus Torvalds1da177e2005-04-16 15:20:36 -07001774mode, which might not be what you want.
1775
1776
Auke Kok6224e012006-06-08 11:15:35 -070017777. Link Monitoring
Linus Torvalds1da177e2005-04-16 15:20:36 -07001778==================
1779
1780 The bonding driver at present supports two schemes for
1781monitoring a slave device's link state: the ARP monitor and the MII
1782monitor.
1783
1784 At the present time, due to implementation restrictions in the
1785bonding driver itself, it is not possible to enable both ARP and MII
1786monitoring simultaneously.
1787
Auke Kok6224e012006-06-08 11:15:35 -070017887.1 ARP Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -07001789-------------------------
1790
1791 The ARP monitor operates as its name suggests: it sends ARP
1792queries to one or more designated peer systems on the network, and
1793uses the response as an indication that the link is operating. This
1794gives some assurance that traffic is actually flowing to and from one
1795or more peers on the local network.
1796
1797 The ARP monitor relies on the device driver itself to verify
1798that traffic is flowing. In particular, the driver must keep up to
1799date the last receive time, dev->last_rx, and transmit start time,
1800dev->trans_start. If these are not updated by the driver, then the
1801ARP monitor will immediately fail any slaves using that driver, and
1802those slaves will stay down. If networking monitoring (tcpdump, etc)
1803shows the ARP requests and replies on the network, then it may be that
1804your device driver is not updating last_rx and trans_start.
1805
Auke Kok6224e012006-06-08 11:15:35 -070018067.2 Configuring Multiple ARP Targets
Linus Torvalds1da177e2005-04-16 15:20:36 -07001807------------------------------------
1808
1809 While ARP monitoring can be done with just one target, it can
1810be useful in a High Availability setup to have several targets to
1811monitor. In the case of just one target, the target itself may go
1812down or have a problem making it unresponsive to ARP requests. Having
1813an additional target (or several) increases the reliability of the ARP
1814monitoring.
1815
Jay Vosburgh00354cf2005-07-21 12:18:02 -07001816 Multiple ARP targets must be separated by commas as follows:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001817
1818# example options for ARP monitoring with three targets
1819alias bond0 bonding
1820options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9
1821
1822 For just a single target the options would resemble:
1823
1824# example options for ARP monitoring with one target
1825alias bond0 bonding
1826options bond0 arp_interval=60 arp_ip_target=192.168.0.100
1827
1828
Auke Kok6224e012006-06-08 11:15:35 -070018297.3 MII Monitor Operation
Linus Torvalds1da177e2005-04-16 15:20:36 -07001830-------------------------
1831
1832 The MII monitor monitors only the carrier state of the local
1833network interface. It accomplishes this in one of three ways: by
1834depending upon the device driver to maintain its carrier state, by
1835querying the device's MII registers, or by making an ethtool query to
1836the device.
1837
1838 If the use_carrier module parameter is 1 (the default value),
1839then the MII monitor will rely on the driver for carrier state
1840information (via the netif_carrier subsystem). As explained in the
1841use_carrier parameter information, above, if the MII monitor fails to
1842detect carrier loss on the device (e.g., when the cable is physically
1843disconnected), it may be that the driver does not support
1844netif_carrier.
1845
1846 If use_carrier is 0, then the MII monitor will first query the
1847device's (via ioctl) MII registers and check the link state. If that
1848request fails (not just that it returns carrier down), then the MII
1849monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain
1850the same information. If both methods fail (i.e., the driver either
1851does not support or had some error in processing both the MII register
1852and ethtool requests), then the MII monitor will assume the link is
1853up.
1854
Auke Kok6224e012006-06-08 11:15:35 -070018558. Potential Sources of Trouble
Linus Torvalds1da177e2005-04-16 15:20:36 -07001856===============================
1857
Auke Kok6224e012006-06-08 11:15:35 -070018588.1 Adventures in Routing
Linus Torvalds1da177e2005-04-16 15:20:36 -07001859-------------------------
1860
1861 When bonding is configured, it is important that the slave
Auke Kok6224e012006-06-08 11:15:35 -07001862devices not have routes that supersede routes of the master (or,
Linus Torvalds1da177e2005-04-16 15:20:36 -07001863generally, not have routes at all). For example, suppose the bonding
1864device bond0 has two slaves, eth0 and eth1, and the routing table is
1865as follows:
1866
1867Kernel IP routing table
1868Destination Gateway Genmask Flags MSS Window irtt Iface
186910.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth0
187010.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth1
187110.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 bond0
1872127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo
1873
1874 This routing configuration will likely still update the
1875receive/transmit times in the driver (needed by the ARP monitor), but
1876may bypass the bonding driver (because outgoing traffic to, in this
1877case, another host on network 10 would use eth0 or eth1 before bond0).
1878
1879 The ARP monitor (and ARP itself) may become confused by this
1880configuration, because ARP requests (generated by the ARP monitor)
1881will be sent on one interface (bond0), but the corresponding reply
1882will arrive on a different interface (eth0). This reply looks to ARP
1883as an unsolicited ARP reply (because ARP matches replies on an
1884interface basis), and is discarded. The MII monitor is not affected
1885by the state of the routing table.
1886
1887 The solution here is simply to insure that slaves do not have
1888routes of their own, and if for some reason they must, those routes do
Auke Kok6224e012006-06-08 11:15:35 -07001889not supersede routes of their master. This should generally be the
Linus Torvalds1da177e2005-04-16 15:20:36 -07001890case, but unusual configurations or errant manual or automatic static
1891route additions may cause trouble.
1892
Auke Kok6224e012006-06-08 11:15:35 -070018938.2 Ethernet Device Renaming
Linus Torvalds1da177e2005-04-16 15:20:36 -07001894----------------------------
1895
1896 On systems with network configuration scripts that do not
1897associate physical devices directly with network interface names (so
1898that the same physical device always has the same "ethX" name), it may
Lucas De Marchi970e2482012-03-30 13:37:16 -07001899be necessary to add some special logic to config files in
1900/etc/modprobe.d/.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001901
1902 For example, given a modules.conf containing the following:
1903
1904alias bond0 bonding
1905options bond0 mode=some-mode miimon=50
1906alias eth0 tg3
1907alias eth1 tg3
1908alias eth2 e1000
1909alias eth3 e1000
1910
1911 If neither eth0 and eth1 are slaves to bond0, then when the
1912bond0 interface comes up, the devices may end up reordered. This
1913happens because bonding is loaded first, then its slave device's
1914drivers are loaded next. Since no other drivers have been loaded,
1915when the e1000 driver loads, it will receive eth0 and eth1 for its
1916devices, but the bonding configuration tries to enslave eth2 and eth3
1917(which may later be assigned to the tg3 devices).
1918
1919 Adding the following:
1920
1921add above bonding e1000 tg3
1922
1923 causes modprobe to load e1000 then tg3, in that order, when
1924bonding is loaded. This command is fully documented in the
1925modules.conf manual page.
1926
Lucas De Marchi970e2482012-03-30 13:37:16 -07001927 On systems utilizing modprobe an equivalent problem can occur.
1928In this case, the following can be added to config files in
1929/etc/modprobe.d/ as:
Linus Torvalds1da177e2005-04-16 15:20:36 -07001930
Lucas De Marchi78286cd2012-03-30 13:37:20 -07001931softdep bonding pre: tg3 e1000
Linus Torvalds1da177e2005-04-16 15:20:36 -07001932
Lucas De Marchi970e2482012-03-30 13:37:16 -07001933 This will load tg3 and e1000 modules before loading the bonding one.
1934Full documentation on this can be found in the modprobe.d and modprobe
1935manual pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001936
Auke Kok6224e012006-06-08 11:15:35 -070019378.3. Painfully Slow Or No Failed Link Detection By Miimon
Linus Torvalds1da177e2005-04-16 15:20:36 -07001938---------------------------------------------------------
1939
1940 By default, bonding enables the use_carrier option, which
1941instructs bonding to trust the driver to maintain carrier state.
1942
1943 As discussed in the options section, above, some drivers do
1944not support the netif_carrier_on/_off link state tracking system.
1945With use_carrier enabled, bonding will always see these links as up,
1946regardless of their actual state.
1947
1948 Additionally, other drivers do support netif_carrier, but do
1949not maintain it in real time, e.g., only polling the link state at
1950some fixed interval. In this case, miimon will detect failures, but
1951only after some long period of time has expired. If it appears that
1952miimon is very slow in detecting link failures, try specifying
1953use_carrier=0 to see if that improves the failure detection time. If
1954it does, then it may be that the driver checks the carrier state at a
1955fixed interval, but does not cache the MII register values (so the
1956use_carrier=0 method of querying the registers directly works). If
1957use_carrier=0 does not improve the failover, then the driver may cache
1958the registers, or the problem may be elsewhere.
1959
1960 Also, remember that miimon only checks for the device's
1961carrier state. It has no way to determine the state of devices on or
1962beyond other ports of a switch, or if a switch is refusing to pass
1963traffic while still maintaining carrier on.
1964
Auke Kok6224e012006-06-08 11:15:35 -070019659. SNMP agents
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966===============
1967
1968 If running SNMP agents, the bonding driver should be loaded
1969before any network drivers participating in a bond. This requirement
Tobias Klauserd533f672005-09-10 00:26:46 -07001970is due to the interface index (ipAdEntIfIndex) being associated to
Linus Torvalds1da177e2005-04-16 15:20:36 -07001971the first interface found with a given IP address. That is, there is
1972only one ipAdEntIfIndex for each IP address. For example, if eth0 and
1973eth1 are slaves of bond0 and the driver for eth0 is loaded before the
1974bonding driver, the interface for the IP address will be associated
1975with the eth0 interface. This configuration is shown below, the IP
1976address 192.168.1.1 has an interface index of 2 which indexes to eth0
1977in the ifDescr table (ifDescr.2).
1978
1979 interfaces.ifTable.ifEntry.ifDescr.1 = lo
1980 interfaces.ifTable.ifEntry.ifDescr.2 = eth0
1981 interfaces.ifTable.ifEntry.ifDescr.3 = eth1
1982 interfaces.ifTable.ifEntry.ifDescr.4 = eth2
1983 interfaces.ifTable.ifEntry.ifDescr.5 = eth3
1984 interfaces.ifTable.ifEntry.ifDescr.6 = bond0
1985 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5
1986 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
1987 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4
1988 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
1989
1990 This problem is avoided by loading the bonding driver before
1991any network drivers participating in a bond. Below is an example of
1992loading the bonding driver first, the IP address 192.168.1.1 is
1993correctly associated with ifDescr.2.
1994
1995 interfaces.ifTable.ifEntry.ifDescr.1 = lo
1996 interfaces.ifTable.ifEntry.ifDescr.2 = bond0
1997 interfaces.ifTable.ifEntry.ifDescr.3 = eth0
1998 interfaces.ifTable.ifEntry.ifDescr.4 = eth1
1999 interfaces.ifTable.ifEntry.ifDescr.5 = eth2
2000 interfaces.ifTable.ifEntry.ifDescr.6 = eth3
2001 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6
2002 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
2003 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5
2004 ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
2005
2006 While some distributions may not report the interface name in
2007ifDescr, the association between the IP address and IfIndex remains
2008and SNMP functions such as Interface_Scan_Next will report that
2009association.
2010
Auke Kok6224e012006-06-08 11:15:35 -0700201110. Promiscuous mode
Linus Torvalds1da177e2005-04-16 15:20:36 -07002012====================
2013
2014 When running network monitoring tools, e.g., tcpdump, it is
2015common to enable promiscuous mode on the device, so that all traffic
2016is seen (instead of seeing only traffic destined for the local host).
2017The bonding driver handles promiscuous mode changes to the bonding
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002018master device (e.g., bond0), and propagates the setting to the slave
Linus Torvalds1da177e2005-04-16 15:20:36 -07002019devices.
2020
2021 For the balance-rr, balance-xor, broadcast, and 802.3ad modes,
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002022the promiscuous mode setting is propagated to all slaves.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002023
2024 For the active-backup, balance-tlb and balance-alb modes, the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002025promiscuous mode setting is propagated only to the active slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002026
2027 For balance-tlb mode, the active slave is the slave currently
2028receiving inbound traffic.
2029
2030 For balance-alb mode, the active slave is the slave used as a
2031"primary." This slave is used for mode-specific control traffic, for
2032sending to peers that are unassigned or if the load is unbalanced.
2033
2034 For the active-backup, balance-tlb and balance-alb modes, when
2035the active slave changes (e.g., due to a link failure), the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002036promiscuous setting will be propagated to the new active slave.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002037
Auke Kok6224e012006-06-08 11:15:35 -0700203811. Configuring Bonding for High Availability
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002039=============================================
Linus Torvalds1da177e2005-04-16 15:20:36 -07002040
2041 High Availability refers to configurations that provide
2042maximum network availability by having redundant or backup devices,
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002043links or switches between the host and the rest of the world. The
2044goal is to provide the maximum availability of network connectivity
2045(i.e., the network always works), even though other configurations
2046could provide higher throughput.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002047
Auke Kok6224e012006-06-08 11:15:35 -0700204811.1 High Availability in a Single Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -07002049--------------------------------------------------
2050
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002051 If two hosts (or a host and a single switch) are directly
2052connected via multiple physical links, then there is no availability
2053penalty to optimizing for maximum bandwidth. In this case, there is
2054only one switch (or peer), so if it fails, there is no alternative
2055access to fail over to. Additionally, the bonding load balance modes
2056support link monitoring of their members, so if individual links fail,
2057the load will be rebalanced across the remaining devices.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002058
Rick Jonesf8b72d32012-07-20 10:51:37 +00002059 See Section 12, "Configuring Bonding for Maximum Throughput"
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002060for information on configuring bonding with one peer device.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002061
Auke Kok6224e012006-06-08 11:15:35 -0700206211.2 High Availability in a Multiple Switch Topology
Linus Torvalds1da177e2005-04-16 15:20:36 -07002063----------------------------------------------------
2064
2065 With multiple switches, the configuration of bonding and the
2066network changes dramatically. In multiple switch topologies, there is
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002067a trade off between network availability and usable bandwidth.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002068
2069 Below is a sample network, configured to maximize the
2070availability of the network:
2071
2072 | |
2073 |port3 port3|
2074 +-----+----+ +-----+----+
2075 | |port2 ISL port2| |
2076 | switch A +--------------------------+ switch B |
2077 | | | |
2078 +-----+----+ +-----++---+
2079 |port1 port1|
2080 | +-------+ |
2081 +-------------+ host1 +---------------+
2082 eth0 +-------+ eth1
2083
2084 In this configuration, there is a link between the two
2085switches (ISL, or inter switch link), and multiple ports connecting to
2086the outside world ("port3" on each switch). There is no technical
2087reason that this could not be extended to a third switch.
2088
Auke Kok6224e012006-06-08 11:15:35 -0700208911.2.1 HA Bonding Mode Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002090-------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002091
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002092 In a topology such as the example above, the active-backup and
2093broadcast modes are the only useful bonding modes when optimizing for
2094availability; the other modes require all links to terminate on the
2095same peer for them to behave rationally.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002096
2097active-backup: This is generally the preferred mode, particularly if
2098 the switches have an ISL and play together well. If the
2099 network configuration is such that one switch is specifically
2100 a backup switch (e.g., has lower capacity, higher cost, etc),
2101 then the primary option can be used to insure that the
2102 preferred link is always used when it is available.
2103
2104broadcast: This mode is really a special purpose mode, and is suitable
2105 only for very specific needs. For example, if the two
2106 switches are not connected (no ISL), and the networks beyond
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002107 them are totally independent. In this case, if it is
Linus Torvalds1da177e2005-04-16 15:20:36 -07002108 necessary for some specific one-way traffic to reach both
2109 independent networks, then the broadcast mode may be suitable.
2110
Auke Kok6224e012006-06-08 11:15:35 -0700211111.2.2 HA Link Monitoring Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002112----------------------------------------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002113
2114 The choice of link monitoring ultimately depends upon your
2115switch. If the switch can reliably fail ports in response to other
2116failures, then either the MII or ARP monitors should work. For
2117example, in the above example, if the "port3" link fails at the remote
2118end, the MII monitor has no direct means to detect this. The ARP
2119monitor could be configured with a target at the remote end of port3,
2120thus detecting that failure without switch support.
2121
2122 In general, however, in a multiple switch topology, the ARP
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002123monitor can provide a higher level of reliability in detecting end to
2124end connectivity failures (which may be caused by the failure of any
2125individual component to pass traffic for any reason). Additionally,
2126the ARP monitor should be configured with multiple targets (at least
2127one for each switch in the network). This will insure that,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002128regardless of which switch is active, the ARP monitor has a suitable
2129target to query.
2130
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002131 Note, also, that of late many switches now support a functionality
2132generally referred to as "trunk failover." This is a feature of the
2133switch that causes the link state of a particular switch port to be set
2134down (or up) when the state of another switch port goes down (or up).
Matt LaPlante19f59462009-04-27 15:06:31 +02002135Its purpose is to propagate link failures from logically "exterior" ports
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002136to the logically "interior" ports that bonding is able to monitor via
2137miimon. Availability and configuration for trunk failover varies by
2138switch, but this can be a viable alternative to the ARP monitor when using
2139suitable switches.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002140
Auke Kok6224e012006-06-08 11:15:35 -0700214112. Configuring Bonding for Maximum Throughput
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002142==============================================
Linus Torvalds1da177e2005-04-16 15:20:36 -07002143
Auke Kok6224e012006-06-08 11:15:35 -0700214412.1 Maximizing Throughput in a Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002145------------------------------------------------------
2146
2147 In a single switch configuration, the best method to maximize
2148throughput depends upon the application and network environment. The
2149various load balancing modes each have strengths and weaknesses in
2150different environments, as detailed below.
2151
2152 For this discussion, we will break down the topologies into
2153two categories. Depending upon the destination of most traffic, we
2154categorize them into either "gatewayed" or "local" configurations.
2155
2156 In a gatewayed configuration, the "switch" is acting primarily
2157as a router, and the majority of traffic passes through this router to
2158other networks. An example would be the following:
2159
2160
2161 +----------+ +----------+
2162 | |eth0 port1| | to other networks
2163 | Host A +---------------------+ router +------------------->
2164 | +---------------------+ | Hosts B and C are out
2165 | |eth1 port2| | here somewhere
2166 +----------+ +----------+
2167
2168 The router may be a dedicated router device, or another host
2169acting as a gateway. For our discussion, the important point is that
2170the majority of traffic from Host A will pass through the router to
2171some other network before reaching its final destination.
2172
2173 In a gatewayed network configuration, although Host A may
2174communicate with many other systems, all of its traffic will be sent
2175and received via one other peer on the local network, the router.
2176
2177 Note that the case of two systems connected directly via
2178multiple physical links is, for purposes of configuring bonding, the
2179same as a gatewayed configuration. In that case, it happens that all
2180traffic is destined for the "gateway" itself, not some other network
2181beyond the gateway.
2182
2183 In a local configuration, the "switch" is acting primarily as
2184a switch, and the majority of traffic passes through this switch to
2185reach other stations on the same network. An example would be the
2186following:
2187
2188 +----------+ +----------+ +--------+
2189 | |eth0 port1| +-------+ Host B |
2190 | Host A +------------+ switch |port3 +--------+
2191 | +------------+ | +--------+
2192 | |eth1 port2| +------------------+ Host C |
2193 +----------+ +----------+port4 +--------+
2194
2195
2196 Again, the switch may be a dedicated switch device, or another
2197host acting as a gateway. For our discussion, the important point is
2198that the majority of traffic from Host A is destined for other hosts
2199on the same local network (Hosts B and C in the above example).
2200
2201 In summary, in a gatewayed configuration, traffic to and from
2202the bonded device will be to the same MAC level peer on the network
2203(the gateway itself, i.e., the router), regardless of its final
2204destination. In a local configuration, traffic flows directly to and
2205from the final destinations, thus, each destination (Host B, Host C)
2206will be addressed directly by their individual MAC addresses.
2207
2208 This distinction between a gatewayed and a local network
2209configuration is important because many of the load balancing modes
2210available use the MAC addresses of the local network source and
2211destination to make load balancing decisions. The behavior of each
2212mode is described below.
2213
2214
Auke Kok6224e012006-06-08 11:15:35 -0700221512.1.1 MT Bonding Mode Selection for Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002216-----------------------------------------------------------
2217
2218 This configuration is the easiest to set up and to understand,
2219although you will have to decide which bonding mode best suits your
2220needs. The trade offs for each mode are detailed below:
2221
2222balance-rr: This mode is the only mode that will permit a single
2223 TCP/IP connection to stripe traffic across multiple
2224 interfaces. It is therefore the only mode that will allow a
2225 single TCP/IP stream to utilize more than one interface's
2226 worth of throughput. This comes at a cost, however: the
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002227 striping generally results in peer systems receiving packets out
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002228 of order, causing TCP/IP's congestion control system to kick
2229 in, often by retransmitting segments.
2230
2231 It is possible to adjust TCP/IP's congestion limits by
2232 altering the net.ipv4.tcp_reordering sysctl parameter. The
2233 usual default value is 3, and the maximum useful value is 127.
2234 For a four interface balance-rr bond, expect that a single
2235 TCP/IP stream will utilize no more than approximately 2.3
2236 interface's worth of throughput, even after adjusting
2237 tcp_reordering.
2238
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002239 Note that the fraction of packets that will be delivered out of
2240 order is highly variable, and is unlikely to be zero. The level
2241 of reordering depends upon a variety of factors, including the
2242 networking interfaces, the switch, and the topology of the
2243 configuration. Speaking in general terms, higher speed network
2244 cards produce more reordering (due to factors such as packet
2245 coalescing), and a "many to many" topology will reorder at a
2246 higher rate than a "many slow to one fast" configuration.
2247
2248 Many switches do not support any modes that stripe traffic
2249 (instead choosing a port based upon IP or MAC level addresses);
2250 for those devices, traffic for a particular connection flowing
2251 through the switch to a balance-rr bond will not utilize greater
2252 than one interface's worth of bandwidth.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002253
2254 If you are utilizing protocols other than TCP/IP, UDP for
2255 example, and your application can tolerate out of order
2256 delivery, then this mode can allow for single stream datagram
2257 performance that scales near linearly as interfaces are added
2258 to the bond.
2259
2260 This mode requires the switch to have the appropriate ports
2261 configured for "etherchannel" or "trunking."
2262
2263active-backup: There is not much advantage in this network topology to
2264 the active-backup mode, as the inactive backup devices are all
2265 connected to the same peer as the primary. In this case, a
2266 load balancing mode (with link monitoring) will provide the
2267 same level of network availability, but with increased
2268 available bandwidth. On the plus side, active-backup mode
2269 does not require any configuration of the switch, so it may
2270 have value if the hardware available does not support any of
2271 the load balance modes.
2272
2273balance-xor: This mode will limit traffic such that packets destined
2274 for specific peers will always be sent over the same
2275 interface. Since the destination is determined by the MAC
2276 addresses involved, this mode works best in a "local" network
2277 configuration (as described above), with destinations all on
2278 the same local network. This mode is likely to be suboptimal
2279 if all your traffic is passed through a single router (i.e., a
2280 "gatewayed" network configuration, as described above).
2281
2282 As with balance-rr, the switch ports need to be configured for
2283 "etherchannel" or "trunking."
2284
2285broadcast: Like active-backup, there is not much advantage to this
2286 mode in this type of network topology.
2287
2288802.3ad: This mode can be a good choice for this type of network
2289 topology. The 802.3ad mode is an IEEE standard, so all peers
2290 that implement 802.3ad should interoperate well. The 802.3ad
2291 protocol includes automatic configuration of the aggregates,
2292 so minimal manual configuration of the switch is needed
2293 (typically only to designate that some set of devices is
2294 available for 802.3ad). The 802.3ad standard also mandates
2295 that frames be delivered in order (within certain limits), so
2296 in general single connections will not see misordering of
2297 packets. The 802.3ad mode does have some drawbacks: the
2298 standard mandates that all devices in the aggregate operate at
2299 the same speed and duplex. Also, as with all bonding load
2300 balance modes other than balance-rr, no single connection will
2301 be able to utilize more than a single interface's worth of
2302 bandwidth.
2303
2304 Additionally, the linux bonding 802.3ad implementation
Jianhua Xie92abf752014-07-17 14:16:26 +08002305 distributes traffic by peer (using an XOR of MAC addresses
2306 and packet type ID), so in a "gatewayed" configuration, all
2307 outgoing traffic will generally use the same device. Incoming
2308 traffic may also end up on a single device, but that is
2309 dependent upon the balancing policy of the peer's 8023.ad
2310 implementation. In a "local" configuration, traffic will be
2311 distributed across the devices in the bond.
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002312
2313 Finally, the 802.3ad mode mandates the use of the MII monitor,
2314 therefore, the ARP monitor is not available in this mode.
2315
2316balance-tlb: The balance-tlb mode balances outgoing traffic by peer.
2317 Since the balancing is done according to MAC address, in a
2318 "gatewayed" configuration (as described above), this mode will
2319 send all traffic across a single device. However, in a
2320 "local" network configuration, this mode balances multiple
2321 local network peers across devices in a vaguely intelligent
2322 manner (not a simple XOR as in balance-xor or 802.3ad mode),
2323 so that mathematically unlucky MAC addresses (i.e., ones that
2324 XOR to the same value) will not all "bunch up" on a single
2325 interface.
2326
2327 Unlike 802.3ad, interfaces may be of differing speeds, and no
2328 special switch configuration is required. On the down side,
2329 in this mode all incoming traffic arrives over a single
2330 interface, this mode requires certain ethtool support in the
2331 network device driver of the slave interfaces, and the ARP
2332 monitor is not available.
2333
2334balance-alb: This mode is everything that balance-tlb is, and more.
2335 It has all of the features (and restrictions) of balance-tlb,
2336 and will also balance incoming traffic from local network
2337 peers (as described in the Bonding Module Options section,
2338 above).
2339
2340 The only additional down side to this mode is that the network
2341 device driver must support changing the hardware address while
2342 the device is open.
2343
Auke Kok6224e012006-06-08 11:15:35 -0700234412.1.2 MT Link Monitoring for Single Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002345----------------------------------------------------
2346
2347 The choice of link monitoring may largely depend upon which
2348mode you choose to use. The more advanced load balancing modes do not
2349support the use of the ARP monitor, and are thus restricted to using
2350the MII monitor (which does not provide as high a level of end to end
2351assurance as the ARP monitor).
2352
Auke Kok6224e012006-06-08 11:15:35 -0700235312.2 Maximum Throughput in a Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002354-----------------------------------------------------
2355
2356 Multiple switches may be utilized to optimize for throughput
2357when they are configured in parallel as part of an isolated network
2358between two or more systems, for example:
2359
2360 +-----------+
2361 | Host A |
2362 +-+---+---+-+
2363 | | |
2364 +--------+ | +---------+
2365 | | |
2366 +------+---+ +-----+----+ +-----+----+
2367 | Switch A | | Switch B | | Switch C |
2368 +------+---+ +-----+----+ +-----+----+
2369 | | |
2370 +--------+ | +---------+
2371 | | |
2372 +-+---+---+-+
2373 | Host B |
2374 +-----------+
2375
2376 In this configuration, the switches are isolated from one
2377another. One reason to employ a topology such as this is for an
2378isolated network with many hosts (a cluster configured for high
2379performance, for example), using multiple smaller switches can be more
2380cost effective than a single larger switch, e.g., on a network with 24
2381hosts, three 24 port switches can be significantly less expensive than
2382a single 72 port switch.
2383
2384 If access beyond the network is required, an individual host
2385can be equipped with an additional network device connected to an
2386external network; this host then additionally acts as a gateway.
2387
Auke Kok6224e012006-06-08 11:15:35 -0700238812.2.1 MT Bonding Mode Selection for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002389-------------------------------------------------------------
2390
2391 In actual practice, the bonding mode typically employed in
2392configurations of this type is balance-rr. Historically, in this
2393network configuration, the usual caveats about out of order packet
2394delivery are mitigated by the use of network adapters that do not do
2395any kind of packet coalescing (via the use of NAPI, or because the
2396device itself does not generate interrupts until some number of
2397packets has arrived). When employed in this fashion, the balance-rr
2398mode allows individual connections between two hosts to effectively
2399utilize greater than one interface's bandwidth.
2400
Auke Kok6224e012006-06-08 11:15:35 -0700240112.2.2 MT Link Monitoring for Multiple Switch Topology
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002402------------------------------------------------------
2403
2404 Again, in actual practice, the MII monitor is most often used
2405in this configuration, as performance is given preference over
2406availability. The ARP monitor will function in this topology, but its
2407advantages over the MII monitor are mitigated by the volume of probes
2408needed as the number of systems involved grows (remember that each
2409host in the network is configured with bonding).
2410
Auke Kok6224e012006-06-08 11:15:35 -0700241113. Switch Behavior Issues
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002412==========================
2413
Auke Kok6224e012006-06-08 11:15:35 -0700241413.1 Link Establishment and Failover Delays
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002415-------------------------------------------
2416
2417 Some switches exhibit undesirable behavior with regard to the
2418timing of link up and down reporting by the switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002419
2420 First, when a link comes up, some switches may indicate that
2421the link is up (carrier available), but not pass traffic over the
2422interface for some period of time. This delay is typically due to
2423some type of autonegotiation or routing protocol, but may also occur
2424during switch initialization (e.g., during recovery after a switch
2425failure). If you find this to be a problem, specify an appropriate
2426value to the updelay bonding module option to delay the use of the
2427relevant interface(s).
2428
2429 Second, some switches may "bounce" the link state one or more
2430times while a link is changing state. This occurs most commonly while
2431the switch is initializing. Again, an appropriate updelay value may
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002432help.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002433
2434 Note that when a bonding interface has no active links, the
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002435driver will immediately reuse the first link that goes up, even if the
2436updelay parameter has been specified (the updelay is ignored in this
2437case). If there are slave interfaces waiting for the updelay timeout
2438to expire, the interface that first went into that state will be
2439immediately reused. This reduces down time of the network if the
2440value of updelay has been overestimated, and since this occurs only in
2441cases with no connectivity, there is no additional penalty for
2442ignoring the updelay.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002443
2444 In addition to the concerns about switch timings, if your
2445switches take a long time to go into backup mode, it may be desirable
2446to not activate a backup interface immediately after a link goes down.
2447Failover may be delayed via the downdelay bonding module option.
2448
Auke Kok6224e012006-06-08 11:15:35 -0700244913.2 Duplicated Incoming Packets
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002450--------------------------------
2451
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002452 NOTE: Starting with version 3.0.2, the bonding driver has logic to
2453suppress duplicate packets, which should largely eliminate this problem.
2454The following description is kept for reference.
2455
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002456 It is not uncommon to observe a short burst of duplicated
2457traffic when the bonding device is first used, or after it has been
2458idle for some period of time. This is most easily observed by issuing
2459a "ping" to some other host on the network, and noticing that the
2460output from ping flags duplicates (typically one per slave).
2461
2462 For example, on a bond in active-backup mode with five slaves
2463all connected to one switch, the output may appear as follows:
2464
2465# ping -n 10.0.4.2
2466PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data.
246764 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms
246864 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
246964 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
247064 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
247164 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
247264 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms
247364 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms
247464 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms
2475
2476 This is not due to an error in the bonding driver, rather, it
2477is a side effect of how many switches update their MAC forwarding
2478tables. Initially, the switch does not associate the MAC address in
2479the packet with a particular switch port, and so it may send the
2480traffic to all ports until its MAC forwarding table is updated. Since
2481the interfaces attached to the bond may occupy multiple ports on a
2482single switch, when the switch (temporarily) floods the traffic to all
2483ports, the bond device receives multiple copies of the same packet
2484(one per slave device).
2485
2486 The duplicated packet behavior is switch dependent, some
2487switches exhibit this, and some do not. On switches that display this
2488behavior, it can be induced by clearing the MAC forwarding table (on
2489most Cisco switches, the privileged command "clear mac address-table
2490dynamic" will accomplish this).
2491
Auke Kok6224e012006-06-08 11:15:35 -0700249214. Hardware Specific Considerations
Linus Torvalds1da177e2005-04-16 15:20:36 -07002493====================================
2494
2495 This section contains additional information for configuring
2496bonding on specific hardware platforms, or for interfacing bonding
2497with particular switches or other devices.
2498
Auke Kok6224e012006-06-08 11:15:35 -0700249914.1 IBM BladeCenter
Linus Torvalds1da177e2005-04-16 15:20:36 -07002500--------------------
2501
2502 This applies to the JS20 and similar systems.
2503
2504 On the JS20 blades, the bonding driver supports only
2505balance-rr, active-backup, balance-tlb and balance-alb modes. This is
2506largely due to the network topology inside the BladeCenter, detailed
2507below.
2508
2509JS20 network adapter information
2510--------------------------------
2511
2512 All JS20s come with two Broadcom Gigabit Ethernet ports
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002513integrated on the planar (that's "motherboard" in IBM-speak). In the
2514BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to
2515I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2.
2516An add-on Broadcom daughter card can be installed on a JS20 to provide
2517two more Gigabit Ethernet ports. These ports, eth2 and eth3, are
2518wired to I/O Modules 3 and 4, respectively.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002519
2520 Each I/O Module may contain either a switch or a passthrough
2521module (which allows ports to be directly connected to an external
2522switch). Some bonding modes require a specific BladeCenter internal
2523network topology in order to function; these are detailed below.
2524
2525 Additional BladeCenter-specific networking information can be
2526found in two IBM Redbooks (www.ibm.com/redbooks):
2527
2528"IBM eServer BladeCenter Networking Options"
2529"IBM eServer BladeCenter Layer 2-7 Network Switching"
2530
2531BladeCenter networking configuration
2532------------------------------------
2533
2534 Because a BladeCenter can be configured in a very large number
2535of ways, this discussion will be confined to describing basic
2536configurations.
2537
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002538 Normally, Ethernet Switch Modules (ESMs) are used in I/O
Linus Torvalds1da177e2005-04-16 15:20:36 -07002539modules 1 and 2. In this configuration, the eth0 and eth1 ports of a
2540JS20 will be connected to different internal switches (in the
2541respective I/O modules).
2542
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002543 A passthrough module (OPM or CPM, optical or copper,
2544passthrough module) connects the I/O module directly to an external
2545switch. By using PMs in I/O module #1 and #2, the eth0 and eth1
2546interfaces of a JS20 can be redirected to the outside world and
2547connected to a common external switch.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002548
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002549 Depending upon the mix of ESMs and PMs, the network will
2550appear to bonding as either a single switch topology (all PMs) or as a
2551multiple switch topology (one or more ESMs, zero or more PMs). It is
2552also possible to connect ESMs together, resulting in a configuration
2553much like the example in "High Availability in a Multiple Switch
2554Topology," above.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002555
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002556Requirements for specific modes
2557-------------------------------
Linus Torvalds1da177e2005-04-16 15:20:36 -07002558
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002559 The balance-rr mode requires the use of passthrough modules
2560for devices in the bond, all connected to an common external switch.
2561That switch must be configured for "etherchannel" or "trunking" on the
Linus Torvalds1da177e2005-04-16 15:20:36 -07002562appropriate ports, as is usual for balance-rr.
2563
2564 The balance-alb and balance-tlb modes will function with
2565either switch modules or passthrough modules (or a mix). The only
2566specific requirement for these modes is that all network interfaces
2567must be able to reach all destinations for traffic sent over the
2568bonding device (i.e., the network must converge at some point outside
2569the BladeCenter).
2570
2571 The active-backup mode has no additional requirements.
2572
2573Link monitoring issues
2574----------------------
2575
2576 When an Ethernet Switch Module is in place, only the ARP
2577monitor will reliably detect link loss to an external switch. This is
2578nothing unusual, but examination of the BladeCenter cabinet would
2579suggest that the "external" network ports are the ethernet ports for
2580the system, when it fact there is a switch between these "external"
2581ports and the devices on the JS20 system itself. The MII monitor is
2582only able to detect link failures between the ESM and the JS20 system.
2583
2584 When a passthrough module is in place, the MII monitor does
2585detect failures to the "external" port, which is then directly
2586connected to the JS20 system.
2587
2588Other concerns
2589--------------
2590
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002591 The Serial Over LAN (SoL) link is established over the primary
Linus Torvalds1da177e2005-04-16 15:20:36 -07002592ethernet (eth0) only, therefore, any loss of link to eth0 will result
2593in losing your SoL connection. It will not fail over with other
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002594network traffic, as the SoL system is beyond the control of the
2595bonding driver.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002596
2597 It may be desirable to disable spanning tree on the switch
2598(either the internal Ethernet Switch Module, or an external switch) to
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002599avoid fail-over delay issues when using bonding.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600
2601
Auke Kok6224e012006-06-08 11:15:35 -0700260215. Frequently Asked Questions
Linus Torvalds1da177e2005-04-16 15:20:36 -07002603==============================
2604
26051. Is it SMP safe?
2606
2607 Yes. The old 2.0.xx channel bonding patch was not SMP safe.
2608The new driver was designed to be SMP safe from the start.
2609
26102. What type of cards will work with it?
2611
2612 Any Ethernet type cards (you can even mix cards - a Intel
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002613EtherExpress PRO/100 and a 3com 3c905b, for example). For most modes,
2614devices need not be of the same speed.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002615
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002616 Starting with version 3.2.1, bonding also supports Infiniband
2617slaves in active-backup mode.
2618
Linus Torvalds1da177e2005-04-16 15:20:36 -070026193. How many bonding devices can I have?
2620
2621 There is no limit.
2622
26234. How many slaves can a bonding device have?
2624
2625 This is limited only by the number of network interfaces Linux
2626supports and/or the number of network cards you can place in your
2627system.
2628
26295. What happens when a slave link dies?
2630
2631 If link monitoring is enabled, then the failing device will be
2632disabled. The active-backup mode will fail over to a backup link, and
2633other modes will ignore the failed link. The link will continue to be
2634monitored, and should it recover, it will rejoin the bond (in whatever
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002635manner is appropriate for the mode). See the sections on High
2636Availability and the documentation for each mode for additional
2637information.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002638
2639 Link monitoring can be enabled via either the miimon or
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002640arp_interval parameters (described in the module parameters section,
Linus Torvalds1da177e2005-04-16 15:20:36 -07002641above). In general, miimon monitors the carrier state as sensed by
2642the underlying network device, and the arp monitor (arp_interval)
2643monitors connectivity to another host on the local network.
2644
2645 If no link monitoring is configured, the bonding driver will
2646be unable to detect link failures, and will assume that all links are
2647always available. This will likely result in lost packets, and a
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002648resulting degradation of performance. The precise performance loss
Linus Torvalds1da177e2005-04-16 15:20:36 -07002649depends upon the bonding mode and network configuration.
2650
26516. Can bonding be used for High Availability?
2652
2653 Yes. See the section on High Availability for details.
2654
26557. Which switches/systems does it work with?
2656
2657 The full answer to this depends upon the desired mode.
2658
2659 In the basic balance modes (balance-rr and balance-xor), it
2660works with any system that supports etherchannel (also called
2661trunking). Most managed switches currently available have such
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002662support, and many unmanaged switches as well.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002663
2664 The advanced balance modes (balance-tlb and balance-alb) do
2665not have special switch requirements, but do need device drivers that
2666support specific features (described in the appropriate section under
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002667module parameters, above).
Linus Torvalds1da177e2005-04-16 15:20:36 -07002668
Auke Kok6224e012006-06-08 11:15:35 -07002669 In 802.3ad mode, it works with systems that support IEEE
Linus Torvalds1da177e2005-04-16 15:20:36 -07002670802.3ad Dynamic Link Aggregation. Most managed and many unmanaged
2671switches currently available support 802.3ad.
2672
2673 The active-backup mode should work with any Layer-II switch.
2674
26758. Where does a bonding device get its MAC address from?
2676
Jay Vosburgh9a6c6862007-11-13 20:25:48 -08002677 When using slave devices that have fixed MAC addresses, or when
2678the fail_over_mac option is enabled, the bonding device's MAC address is
2679the MAC address of the active slave.
2680
2681 For other configurations, if not explicitly configured (with
2682ifconfig or ip link), the MAC address of the bonding device is taken from
2683its first slave device. This MAC address is then passed to all following
2684slaves and remains persistent (even if the first slave is removed) until
2685the bonding device is brought down or reconfigured.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002686
2687 If you wish to change the MAC address, you can set it with
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002688ifconfig or ip link:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002689
2690# ifconfig bond0 hw ether 00:11:22:33:44:55
2691
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002692# ip link set bond0 address 66:77:88:99:aa:bb
2693
Linus Torvalds1da177e2005-04-16 15:20:36 -07002694 The MAC address can be also changed by bringing down/up the
2695device and then changing its slaves (or their order):
2696
2697# ifconfig bond0 down ; modprobe -r bonding
2698# ifconfig bond0 .... up
2699# ifenslave bond0 eth...
2700
2701 This method will automatically take the address from the next
2702slave that is added.
2703
2704 To restore your slaves' MAC addresses, you need to detach them
2705from the bond (`ifenslave -d bond0 eth0'). The bonding driver will
2706then restore the MAC addresses that the slaves had before they were
2707enslaved.
2708
Jay Vosburgh00354cf2005-07-21 12:18:02 -0700270916. Resources and Links
Linus Torvalds1da177e2005-04-16 15:20:36 -07002710=======================
2711
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002712 The latest version of the bonding driver can be found in the latest
Linus Torvalds1da177e2005-04-16 15:20:36 -07002713version of the linux kernel, found on http://kernel.org
2714
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002715 The latest version of this document can be found in the latest kernel
2716source (named Documentation/networking/bonding.txt).
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002717
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002718 Discussions regarding the usage of the bonding driver take place on the
2719bonding-devel mailing list, hosted at sourceforge.net. If you have questions or
2720problems, post them to the list. The list address is:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002721
2722bonding-devel@lists.sourceforge.net
2723
Jay Vosburgh00354cf2005-07-21 12:18:02 -07002724 The administrative interface (to subscribe or unsubscribe) can
2725be found at:
2726
Linus Torvalds1da177e2005-04-16 15:20:36 -07002727https://lists.sourceforge.net/lists/listinfo/bonding-devel
2728
Rick Jonesf8b72d32012-07-20 10:51:37 +00002729 Discussions regarding the development of the bonding driver take place
Nicolas de Pesloüana23c37f12011-03-13 10:34:22 +00002730on the main Linux network mailing list, hosted at vger.kernel.org. The list
2731address is:
2732
2733netdev@vger.kernel.org
2734
2735 The administrative interface (to subscribe or unsubscribe) can
2736be found at:
2737
2738http://vger.kernel.org/vger-lists.html#netdev
2739
Linus Torvalds1da177e2005-04-16 15:20:36 -07002740Donald Becker's Ethernet Drivers and diag programs may be found at :
Justin P. Mattock0ea6e612010-07-23 20:51:24 -07002741 - http://web.archive.org/web/*/http://www.scyld.com/network/
Linus Torvalds1da177e2005-04-16 15:20:36 -07002742
2743You will also find a lot of information regarding Ethernet, NWay, MII,
2744etc. at www.scyld.com.
2745
2746-- END --