Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 2 | Linux Ethernet Bonding Driver HOWTO |
| 3 | |
| 4 | Latest update: 21 June 2005 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 5 | |
| 6 | Initial release : Thomas Davis <tadavis at lbl.gov> |
| 7 | Corrections, 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 | |
| 14 | Reorganized and updated Feb 2005 by Jay Vosburgh |
| 15 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 16 | Introduction |
| 17 | ============ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 19 | The Linux bonding driver provides a method for aggregating |
| 20 | multiple network interfaces into a single logical "bonded" interface. |
| 21 | The behavior of the bonded interfaces depends upon the mode; generally |
| 22 | speaking, modes provide either hot standby or load balancing services. |
| 23 | Additionally, link integrity monitoring may be performed. |
| 24 | |
| 25 | The bonding driver originally came from Donald Becker's |
| 26 | beowulf patches for kernel 2.0. It has changed quite a bit since, and |
| 27 | the original tools from extreme-linux and beowulf sites will not work |
| 28 | with this version of the driver. |
| 29 | |
| 30 | For new versions of the driver, updated userspace tools, and |
| 31 | who to ask for help, please follow the links at the end of this file. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 32 | |
| 33 | Table of Contents |
| 34 | ================= |
| 35 | |
| 36 | 1. Bonding Driver Installation |
| 37 | |
| 38 | 2. Bonding Driver Options |
| 39 | |
| 40 | 3. Configuring Bonding Devices |
| 41 | 3.1 Configuration with sysconfig support |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 42 | 3.1.1 Using DHCP with sysconfig |
| 43 | 3.1.2 Configuring Multiple Bonds with sysconfig |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | 3.2 Configuration with initscripts support |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 45 | 3.2.1 Using DHCP with initscripts |
| 46 | 3.2.2 Configuring Multiple Bonds with initscripts |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 47 | 3.3 Configuring Bonding Manually |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 48 | 3.3.1 Configuring Multiple Bonds Manually |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 49 | |
| 50 | 5. Querying Bonding Configuration |
| 51 | 5.1 Bonding Configuration |
| 52 | 5.2 Network Configuration |
| 53 | |
| 54 | 6. Switch Configuration |
| 55 | |
| 56 | 7. 802.1q VLAN Support |
| 57 | |
| 58 | 8. Link Monitoring |
| 59 | 8.1 ARP Monitor Operation |
| 60 | 8.2 Configuring Multiple ARP Targets |
| 61 | 8.3 MII Monitor Operation |
| 62 | |
| 63 | 9. Potential Trouble Sources |
| 64 | 9.1 Adventures in Routing |
| 65 | 9.2 Ethernet Device Renaming |
| 66 | 9.3 Painfully Slow Or No Failed Link Detection By Miimon |
| 67 | |
| 68 | 10. SNMP agents |
| 69 | |
| 70 | 11. Promiscuous mode |
| 71 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 72 | 12. Configuring Bonding for High Availability |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | 12.1 High Availability in a Single Switch Topology |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | 12.2 High Availability in a Multiple Switch Topology |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 75 | 12.2.1 HA Bonding Mode Selection for Multiple Switch Topology |
| 76 | 12.2.2 HA Link Monitoring for Multiple Switch Topology |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 77 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 78 | 13. Configuring Bonding for Maximum Throughput |
| 79 | 13.1 Maximum Throughput in a Single Switch Topology |
| 80 | 13.1.1 MT Bonding Mode Selection for Single Switch Topology |
| 81 | 13.1.2 MT Link Monitoring for Single Switch Topology |
| 82 | 13.2 Maximum Throughput in a Multiple Switch Topology |
| 83 | 13.2.1 MT Bonding Mode Selection for Multiple Switch Topology |
| 84 | 13.2.2 MT Link Monitoring for Multiple Switch Topology |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 85 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 86 | 14. Switch Behavior Issues |
| 87 | 14.1 Link Establishment and Failover Delays |
| 88 | 14.2 Duplicated Incoming Packets |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 90 | 15. Hardware Specific Considerations |
| 91 | 15.1 IBM BladeCenter |
| 92 | |
| 93 | 16. Frequently Asked Questions |
| 94 | |
| 95 | 17. Resources and Links |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 96 | |
| 97 | |
| 98 | 1. Bonding Driver Installation |
| 99 | ============================== |
| 100 | |
| 101 | Most popular distro kernels ship with the bonding driver |
| 102 | already available as a module and the ifenslave user level control |
| 103 | program installed and ready for use. If your distro does not, or you |
| 104 | have need to compile bonding from source (e.g., configuring and |
| 105 | installing a mainline kernel from kernel.org), you'll need to perform |
| 106 | the following steps: |
| 107 | |
| 108 | 1.1 Configure and build the kernel with bonding |
| 109 | ----------------------------------------------- |
| 110 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 111 | The current version of the bonding driver is available in the |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | drivers/net/bonding subdirectory of the most recent kernel source |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 113 | (which is available on http://kernel.org). Most users "rolling their |
| 114 | own" will want to use the most recent kernel from kernel.org. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | |
| 116 | Configure kernel with "make menuconfig" (or "make xconfig" or |
| 117 | "make config"), then select "Bonding driver support" in the "Network |
| 118 | device support" section. It is recommended that you configure the |
| 119 | driver as module since it is currently the only way to pass parameters |
| 120 | to the driver or configure more than one bonding device. |
| 121 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 122 | Build and install the new kernel and modules, then continue |
| 123 | below to install ifenslave. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 124 | |
| 125 | 1.2 Install ifenslave Control Utility |
| 126 | ------------------------------------- |
| 127 | |
| 128 | The ifenslave user level control program is included in the |
| 129 | kernel source tree, in the file Documentation/networking/ifenslave.c. |
| 130 | It is generally recommended that you use the ifenslave that |
| 131 | corresponds to the kernel that you are using (either from the same |
| 132 | source tree or supplied with the distro), however, ifenslave |
| 133 | executables from older kernels should function (but features newer |
| 134 | than the ifenslave release are not supported). Running an ifenslave |
| 135 | that is newer than the kernel is not supported, and may or may not |
| 136 | work. |
| 137 | |
| 138 | To install ifenslave, do the following: |
| 139 | |
| 140 | # gcc -Wall -O -I/usr/src/linux/include ifenslave.c -o ifenslave |
| 141 | # cp ifenslave /sbin/ifenslave |
| 142 | |
| 143 | If your kernel source is not in "/usr/src/linux," then replace |
| 144 | "/usr/src/linux/include" in the above with the location of your kernel |
| 145 | source include directory. |
| 146 | |
| 147 | You may wish to back up any existing /sbin/ifenslave, or, for |
| 148 | testing or informal use, tag the ifenslave to the kernel version |
| 149 | (e.g., name the ifenslave executable /sbin/ifenslave-2.6.10). |
| 150 | |
| 151 | IMPORTANT NOTE: |
| 152 | |
| 153 | If you omit the "-I" or specify an incorrect directory, you |
| 154 | may end up with an ifenslave that is incompatible with the kernel |
| 155 | you're trying to build it for. Some distros (e.g., Red Hat from 7.1 |
| 156 | onwards) do not have /usr/include/linux symbolically linked to the |
| 157 | default kernel source include directory. |
| 158 | |
| 159 | |
| 160 | 2. Bonding Driver Options |
| 161 | ========================= |
| 162 | |
| 163 | Options for the bonding driver are supplied as parameters to |
| 164 | the bonding module at load time. They may be given as command line |
| 165 | arguments to the insmod or modprobe command, but are usually specified |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 166 | in either the /etc/modules.conf or /etc/modprobe.conf configuration |
| 167 | file, or in a distro-specific configuration file (some of which are |
| 168 | detailed in the next section). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | |
| 170 | The available bonding driver parameters are listed below. If a |
| 171 | parameter is not specified the default value is used. When initially |
| 172 | configuring a bond, it is recommended "tail -f /var/log/messages" be |
| 173 | run in a separate window to watch for bonding driver error messages. |
| 174 | |
| 175 | It is critical that either the miimon or arp_interval and |
| 176 | arp_ip_target parameters be specified, otherwise serious network |
| 177 | degradation will occur during link failures. Very few devices do not |
| 178 | support at least miimon, so there is really no reason not to use it. |
| 179 | |
| 180 | Options with textual values will accept either the text name |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 181 | or, for backwards compatibility, the option value. E.g., |
| 182 | "mode=802.3ad" and "mode=4" set the same mode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 183 | |
| 184 | The parameters are as follows: |
| 185 | |
| 186 | arp_interval |
| 187 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 188 | Specifies the ARP link monitoring frequency in milliseconds. |
| 189 | If ARP monitoring is used in an etherchannel compatible mode |
| 190 | (modes 0 and 2), the switch should be configured in a mode |
| 191 | that evenly distributes packets across all links. If the |
| 192 | switch is configured to distribute the packets in an XOR |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | fashion, all replies from the ARP targets will be received on |
| 194 | the same link which could cause the other team members to |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 195 | fail. ARP monitoring should not be used in conjunction with |
| 196 | miimon. A value of 0 disables ARP monitoring. The default |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | value is 0. |
| 198 | |
| 199 | arp_ip_target |
| 200 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 201 | Specifies the IP addresses to use as ARP monitoring peers when |
| 202 | arp_interval is > 0. These are the targets of the ARP request |
| 203 | sent to determine the health of the link to the targets. |
| 204 | Specify these values in ddd.ddd.ddd.ddd format. Multiple IP |
| 205 | addresses must be separated by a comma. At least one IP |
| 206 | address must be given for ARP monitoring to function. The |
| 207 | maximum number of targets that can be specified is 16. The |
| 208 | default value is no IP addresses. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | |
| 210 | downdelay |
| 211 | |
| 212 | Specifies the time, in milliseconds, to wait before disabling |
| 213 | a slave after a link failure has been detected. This option |
| 214 | is only valid for the miimon link monitor. The downdelay |
| 215 | value should be a multiple of the miimon value; if not, it |
| 216 | will be rounded down to the nearest multiple. The default |
| 217 | value is 0. |
| 218 | |
| 219 | lacp_rate |
| 220 | |
| 221 | Option specifying the rate in which we'll ask our link partner |
| 222 | to transmit LACPDU packets in 802.3ad mode. Possible values |
| 223 | are: |
| 224 | |
| 225 | slow or 0 |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 226 | Request partner to transmit LACPDUs every 30 seconds |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 227 | |
| 228 | fast or 1 |
| 229 | Request partner to transmit LACPDUs every 1 second |
| 230 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 231 | The default is slow. |
| 232 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | max_bonds |
| 234 | |
| 235 | Specifies the number of bonding devices to create for this |
| 236 | instance of the bonding driver. E.g., if max_bonds is 3, and |
| 237 | the bonding driver is not already loaded, then bond0, bond1 |
| 238 | and bond2 will be created. The default value is 1. |
| 239 | |
| 240 | miimon |
| 241 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 242 | Specifies the MII link monitoring frequency in milliseconds. |
| 243 | This determines how often the link state of each slave is |
| 244 | inspected for link failures. A value of zero disables MII |
| 245 | link monitoring. A value of 100 is a good starting point. |
| 246 | The use_carrier option, below, affects how the link state is |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | determined. See the High Availability section for additional |
| 248 | information. The default value is 0. |
| 249 | |
| 250 | mode |
| 251 | |
| 252 | Specifies one of the bonding policies. The default is |
| 253 | balance-rr (round robin). Possible values are: |
| 254 | |
| 255 | balance-rr or 0 |
| 256 | |
| 257 | Round-robin policy: Transmit packets in sequential |
| 258 | order from the first available slave through the |
| 259 | last. This mode provides load balancing and fault |
| 260 | tolerance. |
| 261 | |
| 262 | active-backup or 1 |
| 263 | |
| 264 | Active-backup policy: Only one slave in the bond is |
| 265 | active. A different slave becomes active if, and only |
| 266 | if, the active slave fails. The bond's MAC address is |
| 267 | externally visible on only one port (network adapter) |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 268 | to avoid confusing the switch. |
| 269 | |
| 270 | In bonding version 2.6.2 or later, when a failover |
| 271 | occurs in active-backup mode, bonding will issue one |
| 272 | or more gratuitous ARPs on the newly active slave. |
| 273 | One gratutious ARP is issued for the bonding master |
| 274 | interface and each VLAN interfaces configured above |
| 275 | it, provided that the interface has at least one IP |
| 276 | address configured. Gratuitous ARPs issued for VLAN |
| 277 | interfaces are tagged with the appropriate VLAN id. |
| 278 | |
| 279 | This mode provides fault tolerance. The primary |
| 280 | option, documented below, affects the behavior of this |
| 281 | mode. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 282 | |
| 283 | balance-xor or 2 |
| 284 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 285 | XOR policy: Transmit based on the selected transmit |
| 286 | hash policy. The default policy is a simple [(source |
| 287 | MAC address XOR'd with destination MAC address) modulo |
| 288 | slave count]. Alternate transmit policies may be |
| 289 | selected via the xmit_hash_policy option, described |
| 290 | below. |
| 291 | |
| 292 | This mode provides load balancing and fault tolerance. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 293 | |
| 294 | broadcast or 3 |
| 295 | |
| 296 | Broadcast policy: transmits everything on all slave |
| 297 | interfaces. This mode provides fault tolerance. |
| 298 | |
| 299 | 802.3ad or 4 |
| 300 | |
| 301 | IEEE 802.3ad Dynamic link aggregation. Creates |
| 302 | aggregation groups that share the same speed and |
| 303 | duplex settings. Utilizes all slaves in the active |
| 304 | aggregator according to the 802.3ad specification. |
| 305 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 306 | Slave selection for outgoing traffic is done according |
| 307 | to the transmit hash policy, which may be changed from |
| 308 | the default simple XOR policy via the xmit_hash_policy |
| 309 | option, documented below. Note that not all transmit |
| 310 | policies may be 802.3ad compliant, particularly in |
| 311 | regards to the packet mis-ordering requirements of |
| 312 | section 43.2.4 of the 802.3ad standard. Differing |
| 313 | peer implementations will have varying tolerances for |
| 314 | noncompliance. |
| 315 | |
| 316 | Prerequisites: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 317 | |
| 318 | 1. Ethtool support in the base drivers for retrieving |
| 319 | the speed and duplex of each slave. |
| 320 | |
| 321 | 2. A switch that supports IEEE 802.3ad Dynamic link |
| 322 | aggregation. |
| 323 | |
| 324 | Most switches will require some type of configuration |
| 325 | to enable 802.3ad mode. |
| 326 | |
| 327 | balance-tlb or 5 |
| 328 | |
| 329 | Adaptive transmit load balancing: channel bonding that |
| 330 | does not require any special switch support. The |
| 331 | outgoing traffic is distributed according to the |
| 332 | current load (computed relative to the speed) on each |
| 333 | slave. Incoming traffic is received by the current |
| 334 | slave. If the receiving slave fails, another slave |
| 335 | takes over the MAC address of the failed receiving |
| 336 | slave. |
| 337 | |
| 338 | Prerequisite: |
| 339 | |
| 340 | Ethtool support in the base drivers for retrieving the |
| 341 | speed of each slave. |
| 342 | |
| 343 | balance-alb or 6 |
| 344 | |
| 345 | Adaptive load balancing: includes balance-tlb plus |
| 346 | receive load balancing (rlb) for IPV4 traffic, and |
| 347 | does not require any special switch support. The |
| 348 | receive load balancing is achieved by ARP negotiation. |
| 349 | The bonding driver intercepts the ARP Replies sent by |
| 350 | the local system on their way out and overwrites the |
| 351 | source hardware address with the unique hardware |
| 352 | address of one of the slaves in the bond such that |
| 353 | different peers use different hardware addresses for |
| 354 | the server. |
| 355 | |
| 356 | Receive traffic from connections created by the server |
| 357 | is also balanced. When the local system sends an ARP |
| 358 | Request the bonding driver copies and saves the peer's |
| 359 | IP information from the ARP packet. When the ARP |
| 360 | Reply arrives from the peer, its hardware address is |
| 361 | retrieved and the bonding driver initiates an ARP |
| 362 | reply to this peer assigning it to one of the slaves |
| 363 | in the bond. A problematic outcome of using ARP |
| 364 | negotiation for balancing is that each time that an |
| 365 | ARP request is broadcast it uses the hardware address |
| 366 | of the bond. Hence, peers learn the hardware address |
| 367 | of the bond and the balancing of receive traffic |
| 368 | collapses to the current slave. This is handled by |
| 369 | sending updates (ARP Replies) to all the peers with |
| 370 | their individually assigned hardware address such that |
| 371 | the traffic is redistributed. Receive traffic is also |
| 372 | redistributed when a new slave is added to the bond |
| 373 | and when an inactive slave is re-activated. The |
| 374 | receive load is distributed sequentially (round robin) |
| 375 | among the group of highest speed slaves in the bond. |
| 376 | |
| 377 | When a link is reconnected or a new slave joins the |
| 378 | bond the receive traffic is redistributed among all |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 379 | active slaves in the bond by initiating ARP Replies |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | with the selected mac address to each of the |
| 381 | clients. The updelay parameter (detailed below) must |
| 382 | be set to a value equal or greater than the switch's |
| 383 | forwarding delay so that the ARP Replies sent to the |
| 384 | peers will not be blocked by the switch. |
| 385 | |
| 386 | Prerequisites: |
| 387 | |
| 388 | 1. Ethtool support in the base drivers for retrieving |
| 389 | the speed of each slave. |
| 390 | |
| 391 | 2. Base driver support for setting the hardware |
| 392 | address of a device while it is open. This is |
| 393 | required so that there will always be one slave in the |
| 394 | team using the bond hardware address (the |
| 395 | curr_active_slave) while having a unique hardware |
| 396 | address for each slave in the bond. If the |
| 397 | curr_active_slave fails its hardware address is |
| 398 | swapped with the new curr_active_slave that was |
| 399 | chosen. |
| 400 | |
| 401 | primary |
| 402 | |
| 403 | A string (eth0, eth2, etc) specifying which slave is the |
| 404 | primary device. The specified device will always be the |
| 405 | active slave while it is available. Only when the primary is |
| 406 | off-line will alternate devices be used. This is useful when |
| 407 | one slave is preferred over another, e.g., when one slave has |
| 408 | higher throughput than another. |
| 409 | |
| 410 | The primary option is only valid for active-backup mode. |
| 411 | |
| 412 | updelay |
| 413 | |
| 414 | Specifies the time, in milliseconds, to wait before enabling a |
| 415 | slave after a link recovery has been detected. This option is |
| 416 | only valid for the miimon link monitor. The updelay value |
| 417 | should be a multiple of the miimon value; if not, it will be |
| 418 | rounded down to the nearest multiple. The default value is 0. |
| 419 | |
| 420 | use_carrier |
| 421 | |
| 422 | Specifies whether or not miimon should use MII or ETHTOOL |
| 423 | ioctls vs. netif_carrier_ok() to determine the link |
| 424 | status. The MII or ETHTOOL ioctls are less efficient and |
| 425 | utilize a deprecated calling sequence within the kernel. The |
| 426 | netif_carrier_ok() relies on the device driver to maintain its |
| 427 | state with netif_carrier_on/off; at this writing, most, but |
| 428 | not all, device drivers support this facility. |
| 429 | |
| 430 | If bonding insists that the link is up when it should not be, |
| 431 | it may be that your network device driver does not support |
| 432 | netif_carrier_on/off. The default state for netif_carrier is |
| 433 | "carrier on," so if a driver does not support netif_carrier, |
| 434 | it will appear as if the link is always up. In this case, |
| 435 | setting use_carrier to 0 will cause bonding to revert to the |
| 436 | MII / ETHTOOL ioctl method to determine the link state. |
| 437 | |
| 438 | A value of 1 enables the use of netif_carrier_ok(), a value of |
| 439 | 0 will use the deprecated MII / ETHTOOL ioctls. The default |
| 440 | value is 1. |
| 441 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 442 | xmit_hash_policy |
| 443 | |
| 444 | Selects the transmit hash policy to use for slave selection in |
| 445 | balance-xor and 802.3ad modes. Possible values are: |
| 446 | |
| 447 | layer2 |
| 448 | |
| 449 | Uses XOR of hardware MAC addresses to generate the |
| 450 | hash. The formula is |
| 451 | |
| 452 | (source MAC XOR destination MAC) modulo slave count |
| 453 | |
| 454 | This algorithm will place all traffic to a particular |
| 455 | network peer on the same slave. |
| 456 | |
| 457 | This algorithm is 802.3ad compliant. |
| 458 | |
| 459 | layer3+4 |
| 460 | |
| 461 | This policy uses upper layer protocol information, |
| 462 | when available, to generate the hash. This allows for |
| 463 | traffic to a particular network peer to span multiple |
| 464 | slaves, although a single connection will not span |
| 465 | multiple slaves. |
| 466 | |
| 467 | The formula for unfragmented TCP and UDP packets is |
| 468 | |
| 469 | ((source port XOR dest port) XOR |
| 470 | ((source IP XOR dest IP) AND 0xffff) |
| 471 | modulo slave count |
| 472 | |
| 473 | For fragmented TCP or UDP packets and all other IP |
| 474 | protocol traffic, the source and destination port |
| 475 | information is omitted. For non-IP traffic, the |
| 476 | formula is the same as for the layer2 transmit hash |
| 477 | policy. |
| 478 | |
| 479 | This policy is intended to mimic the behavior of |
| 480 | certain switches, notably Cisco switches with PFC2 as |
| 481 | well as some Foundry and IBM products. |
| 482 | |
| 483 | This algorithm is not fully 802.3ad compliant. A |
| 484 | single TCP or UDP conversation containing both |
| 485 | fragmented and unfragmented packets will see packets |
| 486 | striped across two interfaces. This may result in out |
| 487 | of order delivery. Most traffic types will not meet |
| 488 | this criteria, as TCP rarely fragments traffic, and |
| 489 | most UDP traffic is not involved in extended |
| 490 | conversations. Other implementations of 802.3ad may |
| 491 | or may not tolerate this noncompliance. |
| 492 | |
| 493 | The default value is layer2. This option was added in bonding |
| 494 | version 2.6.3. In earlier versions of bonding, this parameter does |
| 495 | not exist, and the layer2 policy is the only policy. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 496 | |
| 497 | |
| 498 | 3. Configuring Bonding Devices |
| 499 | ============================== |
| 500 | |
| 501 | There are, essentially, two methods for configuring bonding: |
| 502 | with support from the distro's network initialization scripts, and |
| 503 | without. Distros generally use one of two packages for the network |
| 504 | initialization scripts: initscripts or sysconfig. Recent versions of |
| 505 | these packages have support for bonding, while older versions do not. |
| 506 | |
| 507 | We will first describe the options for configuring bonding for |
| 508 | distros using versions of initscripts and sysconfig with full or |
| 509 | partial support for bonding, then provide information on enabling |
| 510 | bonding without support from the network initialization scripts (i.e., |
| 511 | older versions of initscripts or sysconfig). |
| 512 | |
| 513 | If you're unsure whether your distro uses sysconfig or |
| 514 | initscripts, or don't know if it's new enough, have no fear. |
| 515 | Determining this is fairly straightforward. |
| 516 | |
| 517 | First, issue the command: |
| 518 | |
| 519 | $ rpm -qf /sbin/ifup |
| 520 | |
| 521 | It will respond with a line of text starting with either |
| 522 | "initscripts" or "sysconfig," followed by some numbers. This is the |
| 523 | package that provides your network initialization scripts. |
| 524 | |
| 525 | Next, to determine if your installation supports bonding, |
| 526 | issue the command: |
| 527 | |
| 528 | $ grep ifenslave /sbin/ifup |
| 529 | |
| 530 | If this returns any matches, then your initscripts or |
| 531 | sysconfig has support for bonding. |
| 532 | |
| 533 | 3.1 Configuration with sysconfig support |
| 534 | ---------------------------------------- |
| 535 | |
| 536 | This section applies to distros using a version of sysconfig |
| 537 | with bonding support, for example, SuSE Linux Enterprise Server 9. |
| 538 | |
| 539 | SuSE SLES 9's networking configuration system does support |
| 540 | bonding, however, at this writing, the YaST system configuration |
| 541 | frontend does not provide any means to work with bonding devices. |
| 542 | Bonding devices can be managed by hand, however, as follows. |
| 543 | |
| 544 | First, if they have not already been configured, configure the |
| 545 | slave devices. On SLES 9, this is most easily done by running the |
| 546 | yast2 sysconfig configuration utility. The goal is for to create an |
| 547 | ifcfg-id file for each slave device. The simplest way to accomplish |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 548 | this is to configure the devices for DHCP (this is only to get the |
| 549 | file ifcfg-id file created; see below for some issues with DHCP). The |
| 550 | name of the configuration file for each device will be of the form: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 551 | |
| 552 | ifcfg-id-xx:xx:xx:xx:xx:xx |
| 553 | |
| 554 | Where the "xx" portion will be replaced with the digits from |
| 555 | the device's permanent MAC address. |
| 556 | |
| 557 | Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been |
| 558 | created, it is necessary to edit the configuration files for the slave |
| 559 | devices (the MAC addresses correspond to those of the slave devices). |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 560 | Before editing, the file will contain multiple lines, and will look |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 561 | something like this: |
| 562 | |
| 563 | BOOTPROTO='dhcp' |
| 564 | STARTMODE='on' |
| 565 | USERCTL='no' |
| 566 | UNIQUE='XNzu.WeZGOGF+4wE' |
| 567 | _nm_name='bus-pci-0001:61:01.0' |
| 568 | |
| 569 | Change the BOOTPROTO and STARTMODE lines to the following: |
| 570 | |
| 571 | BOOTPROTO='none' |
| 572 | STARTMODE='off' |
| 573 | |
| 574 | Do not alter the UNIQUE or _nm_name lines. Remove any other |
| 575 | lines (USERCTL, etc). |
| 576 | |
| 577 | Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified, |
| 578 | it's time to create the configuration file for the bonding device |
| 579 | itself. This file is named ifcfg-bondX, where X is the number of the |
| 580 | bonding device to create, starting at 0. The first such file is |
| 581 | ifcfg-bond0, the second is ifcfg-bond1, and so on. The sysconfig |
| 582 | network configuration system will correctly start multiple instances |
| 583 | of bonding. |
| 584 | |
| 585 | The contents of the ifcfg-bondX file is as follows: |
| 586 | |
| 587 | BOOTPROTO="static" |
| 588 | BROADCAST="10.0.2.255" |
| 589 | IPADDR="10.0.2.10" |
| 590 | NETMASK="255.255.0.0" |
| 591 | NETWORK="10.0.2.0" |
| 592 | REMOTE_IPADDR="" |
| 593 | STARTMODE="onboot" |
| 594 | BONDING_MASTER="yes" |
| 595 | BONDING_MODULE_OPTS="mode=active-backup miimon=100" |
| 596 | BONDING_SLAVE0="eth0" |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 597 | BONDING_SLAVE1="bus-pci-0000:06:08.1" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 598 | |
| 599 | Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK |
| 600 | values with the appropriate values for your network. |
| 601 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 602 | The STARTMODE specifies when the device is brought online. |
| 603 | The possible values are: |
| 604 | |
| 605 | onboot: The device is started at boot time. If you're not |
| 606 | sure, this is probably what you want. |
| 607 | |
| 608 | manual: The device is started only when ifup is called |
| 609 | manually. Bonding devices may be configured this |
| 610 | way if you do not wish them to start automatically |
| 611 | at boot for some reason. |
| 612 | |
| 613 | hotplug: The device is started by a hotplug event. This is not |
| 614 | a valid choice for a bonding device. |
| 615 | |
| 616 | off or ignore: The device configuration is ignored. |
| 617 | |
| 618 | The line BONDING_MASTER='yes' indicates that the device is a |
| 619 | bonding master device. The only useful value is "yes." |
| 620 | |
| 621 | The contents of BONDING_MODULE_OPTS are supplied to the |
| 622 | instance of the bonding module for this device. Specify the options |
| 623 | for the bonding mode, link monitoring, and so on here. Do not include |
| 624 | the max_bonds bonding parameter; this will confuse the configuration |
| 625 | system if you have multiple bonding devices. |
| 626 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 627 | Finally, supply one BONDING_SLAVEn="slave device" for each |
| 628 | slave. where "n" is an increasing value, one for each slave. The |
| 629 | "slave device" is either an interface name, e.g., "eth0", or a device |
| 630 | specifier for the network device. The interface name is easier to |
| 631 | find, but the ethN names are subject to change at boot time if, e.g., |
| 632 | a device early in the sequence has failed. The device specifiers |
| 633 | (bus-pci-0000:06:08.1 in the example above) specify the physical |
| 634 | network device, and will not change unless the device's bus location |
| 635 | changes (for example, it is moved from one PCI slot to another). The |
| 636 | example above uses one of each type for demonstration purposes; most |
| 637 | configurations will choose one or the other for all slave devices. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 638 | |
| 639 | When all configuration files have been modified or created, |
| 640 | networking must be restarted for the configuration changes to take |
| 641 | effect. This can be accomplished via the following: |
| 642 | |
| 643 | # /etc/init.d/network restart |
| 644 | |
| 645 | Note that the network control script (/sbin/ifdown) will |
| 646 | remove the bonding module as part of the network shutdown processing, |
| 647 | so it is not necessary to remove the module by hand if, e.g., the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 648 | module parameters have changed. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 649 | |
| 650 | Also, at this writing, YaST/YaST2 will not manage bonding |
| 651 | devices (they do not show bonding interfaces on its list of network |
| 652 | devices). It is necessary to edit the configuration file by hand to |
| 653 | change the bonding configuration. |
| 654 | |
| 655 | Additional general options and details of the ifcfg file |
| 656 | format can be found in an example ifcfg template file: |
| 657 | |
| 658 | /etc/sysconfig/network/ifcfg.template |
| 659 | |
| 660 | Note that the template does not document the various BONDING_ |
| 661 | settings described above, but does describe many of the other options. |
| 662 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 663 | 3.1.1 Using DHCP with sysconfig |
| 664 | ------------------------------- |
| 665 | |
| 666 | Under sysconfig, configuring a device with BOOTPROTO='dhcp' |
| 667 | will cause it to query DHCP for its IP address information. At this |
| 668 | writing, this does not function for bonding devices; the scripts |
| 669 | attempt to obtain the device address from DHCP prior to adding any of |
| 670 | the slave devices. Without active slaves, the DHCP requests are not |
| 671 | sent to the network. |
| 672 | |
| 673 | 3.1.2 Configuring Multiple Bonds with sysconfig |
| 674 | ----------------------------------------------- |
| 675 | |
| 676 | The sysconfig network initialization system is capable of |
| 677 | handling multiple bonding devices. All that is necessary is for each |
| 678 | bonding instance to have an appropriately configured ifcfg-bondX file |
| 679 | (as described above). Do not specify the "max_bonds" parameter to any |
| 680 | instance of bonding, as this will confuse sysconfig. If you require |
| 681 | multiple bonding devices with identical parameters, create multiple |
| 682 | ifcfg-bondX files. |
| 683 | |
| 684 | Because the sysconfig scripts supply the bonding module |
| 685 | options in the ifcfg-bondX file, it is not necessary to add them to |
| 686 | the system /etc/modules.conf or /etc/modprobe.conf configuration file. |
| 687 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 688 | 3.2 Configuration with initscripts support |
| 689 | ------------------------------------------ |
| 690 | |
| 691 | This section applies to distros using a version of initscripts |
| 692 | with bonding support, for example, Red Hat Linux 9 or Red Hat |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 693 | Enterprise Linux version 3 or 4. On these systems, the network |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 694 | initialization scripts have some knowledge of bonding, and can be |
| 695 | configured to control bonding devices. |
| 696 | |
| 697 | These distros will not automatically load the network adapter |
| 698 | driver unless the ethX device is configured with an IP address. |
| 699 | Because of this constraint, users must manually configure a |
| 700 | network-script file for all physical adapters that will be members of |
| 701 | a bondX link. Network script files are located in the directory: |
| 702 | |
| 703 | /etc/sysconfig/network-scripts |
| 704 | |
| 705 | The file name must be prefixed with "ifcfg-eth" and suffixed |
| 706 | with the adapter's physical adapter number. For example, the script |
| 707 | for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0. |
| 708 | Place the following text in the file: |
| 709 | |
| 710 | DEVICE=eth0 |
| 711 | USERCTL=no |
| 712 | ONBOOT=yes |
| 713 | MASTER=bond0 |
| 714 | SLAVE=yes |
| 715 | BOOTPROTO=none |
| 716 | |
| 717 | The DEVICE= line will be different for every ethX device and |
| 718 | must correspond with the name of the file, i.e., ifcfg-eth1 must have |
| 719 | a device line of DEVICE=eth1. The setting of the MASTER= line will |
| 720 | also depend on the final bonding interface name chosen for your bond. |
| 721 | As with other network devices, these typically start at 0, and go up |
| 722 | one for each device, i.e., the first bonding instance is bond0, the |
| 723 | second is bond1, and so on. |
| 724 | |
| 725 | Next, create a bond network script. The file name for this |
| 726 | script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is |
| 727 | the number of the bond. For bond0 the file is named "ifcfg-bond0", |
| 728 | for bond1 it is named "ifcfg-bond1", and so on. Within that file, |
| 729 | place the following text: |
| 730 | |
| 731 | DEVICE=bond0 |
| 732 | IPADDR=192.168.1.1 |
| 733 | NETMASK=255.255.255.0 |
| 734 | NETWORK=192.168.1.0 |
| 735 | BROADCAST=192.168.1.255 |
| 736 | ONBOOT=yes |
| 737 | BOOTPROTO=none |
| 738 | USERCTL=no |
| 739 | |
| 740 | Be sure to change the networking specific lines (IPADDR, |
| 741 | NETMASK, NETWORK and BROADCAST) to match your network configuration. |
| 742 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 743 | Finally, it is necessary to edit /etc/modules.conf (or |
| 744 | /etc/modprobe.conf, depending upon your distro) to load the bonding |
| 745 | module with your desired options when the bond0 interface is brought |
| 746 | up. The following lines in /etc/modules.conf (or modprobe.conf) will |
| 747 | load the bonding module, and select its options: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 748 | |
| 749 | alias bond0 bonding |
| 750 | options bond0 mode=balance-alb miimon=100 |
| 751 | |
| 752 | Replace the sample parameters with the appropriate set of |
| 753 | options for your configuration. |
| 754 | |
| 755 | Finally run "/etc/rc.d/init.d/network restart" as root. This |
| 756 | will restart the networking subsystem and your bond link should be now |
| 757 | up and running. |
| 758 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 759 | 3.2.1 Using DHCP with initscripts |
| 760 | --------------------------------- |
| 761 | |
| 762 | Recent versions of initscripts (the version supplied with |
| 763 | Fedora Core 3 and Red Hat Enterprise Linux 4 is reported to work) do |
| 764 | have support for assigning IP information to bonding devices via DHCP. |
| 765 | |
| 766 | To configure bonding for DHCP, configure it as described |
| 767 | above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp" |
| 768 | and add a line consisting of "TYPE=Bonding". Note that the TYPE value |
| 769 | is case sensitive. |
| 770 | |
| 771 | 3.2.2 Configuring Multiple Bonds with initscripts |
| 772 | ------------------------------------------------- |
| 773 | |
| 774 | At this writing, the initscripts package does not directly |
| 775 | support loading the bonding driver multiple times, so the process for |
| 776 | doing so is the same as described in the "Configuring Multiple Bonds |
| 777 | Manually" section, below. |
| 778 | |
| 779 | NOTE: It has been observed that some Red Hat supplied kernels |
| 780 | are apparently unable to rename modules at load time (the "-obonding1" |
| 781 | part). Attempts to pass that option to modprobe will produce an |
| 782 | "Operation not permitted" error. This has been reported on some |
| 783 | Fedora Core kernels, and has been seen on RHEL 4 as well. On kernels |
| 784 | exhibiting this problem, it will be impossible to configure multiple |
| 785 | bonds with differing parameters. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 786 | |
| 787 | 3.3 Configuring Bonding Manually |
| 788 | -------------------------------- |
| 789 | |
| 790 | This section applies to distros whose network initialization |
| 791 | scripts (the sysconfig or initscripts package) do not have specific |
| 792 | knowledge of bonding. One such distro is SuSE Linux Enterprise Server |
| 793 | version 8. |
| 794 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 795 | The general method for these systems is to place the bonding |
| 796 | module parameters into /etc/modules.conf or /etc/modprobe.conf (as |
| 797 | appropriate for the installed distro), then add modprobe and/or |
| 798 | ifenslave commands to the system's global init script. The name of |
| 799 | the global init script differs; for sysconfig, it is |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 800 | /etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local. |
| 801 | |
| 802 | For example, if you wanted to make a simple bond of two e100 |
| 803 | devices (presumed to be eth0 and eth1), and have it persist across |
| 804 | reboots, edit the appropriate file (/etc/init.d/boot.local or |
| 805 | /etc/rc.d/rc.local), and add the following: |
| 806 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 807 | modprobe bonding mode=balance-alb miimon=100 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 808 | modprobe e100 |
| 809 | ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up |
| 810 | ifenslave bond0 eth0 |
| 811 | ifenslave bond0 eth1 |
| 812 | |
| 813 | Replace the example bonding module parameters and bond0 |
| 814 | network configuration (IP address, netmask, etc) with the appropriate |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 815 | values for your configuration. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 816 | |
| 817 | Unfortunately, this method will not provide support for the |
| 818 | ifup and ifdown scripts on the bond devices. To reload the bonding |
| 819 | configuration, it is necessary to run the initialization script, e.g., |
| 820 | |
| 821 | # /etc/init.d/boot.local |
| 822 | |
| 823 | or |
| 824 | |
| 825 | # /etc/rc.d/rc.local |
| 826 | |
| 827 | It may be desirable in such a case to create a separate script |
| 828 | which only initializes the bonding configuration, then call that |
| 829 | separate script from within boot.local. This allows for bonding to be |
| 830 | enabled without re-running the entire global init script. |
| 831 | |
| 832 | To shut down the bonding devices, it is necessary to first |
| 833 | mark the bonding device itself as being down, then remove the |
| 834 | appropriate device driver modules. For our example above, you can do |
| 835 | the following: |
| 836 | |
| 837 | # ifconfig bond0 down |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 838 | # rmmod bonding |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 839 | # rmmod e100 |
| 840 | |
| 841 | Again, for convenience, it may be desirable to create a script |
| 842 | with these commands. |
| 843 | |
| 844 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 845 | 3.3.1 Configuring Multiple Bonds Manually |
| 846 | ----------------------------------------- |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 847 | |
| 848 | This section contains information on configuring multiple |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 849 | bonding devices with differing options for those systems whose network |
| 850 | initialization scripts lack support for configuring multiple bonds. |
| 851 | |
| 852 | If you require multiple bonding devices, but all with the same |
| 853 | options, you may wish to use the "max_bonds" module parameter, |
| 854 | documented above. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 855 | |
| 856 | To create multiple bonding devices with differing options, it |
| 857 | is necessary to load the bonding driver multiple times. Note that |
| 858 | current versions of the sysconfig network initialization scripts |
| 859 | handle this automatically; if your distro uses these scripts, no |
| 860 | special action is needed. See the section Configuring Bonding |
| 861 | Devices, above, if you're not sure about your network initialization |
| 862 | scripts. |
| 863 | |
| 864 | To load multiple instances of the module, it is necessary to |
| 865 | specify a different name for each instance (the module loading system |
| 866 | requires that every loaded module, even multiple instances of the same |
| 867 | module, have a unique name). This is accomplished by supplying |
| 868 | multiple sets of bonding options in /etc/modprobe.conf, for example: |
| 869 | |
| 870 | alias bond0 bonding |
| 871 | options bond0 -o bond0 mode=balance-rr miimon=100 |
| 872 | |
| 873 | alias bond1 bonding |
| 874 | options bond1 -o bond1 mode=balance-alb miimon=50 |
| 875 | |
| 876 | will load the bonding module two times. The first instance is |
| 877 | named "bond0" and creates the bond0 device in balance-rr mode with an |
| 878 | miimon of 100. The second instance is named "bond1" and creates the |
| 879 | bond1 device in balance-alb mode with an miimon of 50. |
| 880 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 881 | In some circumstances (typically with older distributions), |
| 882 | the above does not work, and the second bonding instance never sees |
| 883 | its options. In that case, the second options line can be substituted |
| 884 | as follows: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 885 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 886 | install bonding1 /sbin/modprobe bonding -obond1 mode=balance-alb miimon=50 |
| 887 | |
| 888 | This may be repeated any number of times, specifying a new and |
| 889 | unique name in place of bond1 for each subsequent instance. |
| 890 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 891 | |
| 892 | 5. Querying Bonding Configuration |
| 893 | ================================= |
| 894 | |
| 895 | 5.1 Bonding Configuration |
| 896 | ------------------------- |
| 897 | |
| 898 | Each bonding device has a read-only file residing in the |
| 899 | /proc/net/bonding directory. The file contents include information |
| 900 | about the bonding configuration, options and state of each slave. |
| 901 | |
| 902 | For example, the contents of /proc/net/bonding/bond0 after the |
| 903 | driver is loaded with parameters of mode=0 and miimon=1000 is |
| 904 | generally as follows: |
| 905 | |
| 906 | Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004) |
| 907 | Bonding Mode: load balancing (round-robin) |
| 908 | Currently Active Slave: eth0 |
| 909 | MII Status: up |
| 910 | MII Polling Interval (ms): 1000 |
| 911 | Up Delay (ms): 0 |
| 912 | Down Delay (ms): 0 |
| 913 | |
| 914 | Slave Interface: eth1 |
| 915 | MII Status: up |
| 916 | Link Failure Count: 1 |
| 917 | |
| 918 | Slave Interface: eth0 |
| 919 | MII Status: up |
| 920 | Link Failure Count: 1 |
| 921 | |
| 922 | The precise format and contents will change depending upon the |
| 923 | bonding configuration, state, and version of the bonding driver. |
| 924 | |
| 925 | 5.2 Network configuration |
| 926 | ------------------------- |
| 927 | |
| 928 | The network configuration can be inspected using the ifconfig |
| 929 | command. Bonding devices will have the MASTER flag set; Bonding slave |
| 930 | devices will have the SLAVE flag set. The ifconfig output does not |
| 931 | contain information on which slaves are associated with which masters. |
| 932 | |
| 933 | In the example below, the bond0 interface is the master |
| 934 | (MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of |
| 935 | bond0 have the same MAC address (HWaddr) as bond0 for all modes except |
| 936 | TLB and ALB that require a unique MAC address for each slave. |
| 937 | |
| 938 | # /sbin/ifconfig |
| 939 | bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 |
| 940 | inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0 |
| 941 | UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 |
| 942 | RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0 |
| 943 | TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0 |
| 944 | collisions:0 txqueuelen:0 |
| 945 | |
| 946 | eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 |
| 947 | inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0 |
| 948 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
| 949 | RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0 |
| 950 | TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0 |
| 951 | collisions:0 txqueuelen:100 |
| 952 | Interrupt:10 Base address:0x1080 |
| 953 | |
| 954 | eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 |
| 955 | inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0 |
| 956 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
| 957 | RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0 |
| 958 | TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0 |
| 959 | collisions:0 txqueuelen:100 |
| 960 | Interrupt:9 Base address:0x1400 |
| 961 | |
| 962 | 6. Switch Configuration |
| 963 | ======================= |
| 964 | |
| 965 | For this section, "switch" refers to whatever system the |
| 966 | bonded devices are directly connected to (i.e., where the other end of |
| 967 | the cable plugs into). This may be an actual dedicated switch device, |
| 968 | or it may be another regular system (e.g., another computer running |
| 969 | Linux), |
| 970 | |
| 971 | The active-backup, balance-tlb and balance-alb modes do not |
| 972 | require any specific configuration of the switch. |
| 973 | |
| 974 | The 802.3ad mode requires that the switch have the appropriate |
| 975 | ports configured as an 802.3ad aggregation. The precise method used |
| 976 | to configure this varies from switch to switch, but, for example, a |
| 977 | Cisco 3550 series switch requires that the appropriate ports first be |
| 978 | grouped together in a single etherchannel instance, then that |
| 979 | etherchannel is set to mode "lacp" to enable 802.3ad (instead of |
| 980 | standard EtherChannel). |
| 981 | |
| 982 | The balance-rr, balance-xor and broadcast modes generally |
| 983 | require that the switch have the appropriate ports grouped together. |
| 984 | The nomenclature for such a group differs between switches, it may be |
| 985 | called an "etherchannel" (as in the Cisco example, above), a "trunk |
| 986 | group" or some other similar variation. For these modes, each switch |
| 987 | will also have its own configuration options for the switch's transmit |
| 988 | policy to the bond. Typical choices include XOR of either the MAC or |
| 989 | IP addresses. The transmit policy of the two peers does not need to |
| 990 | match. For these three modes, the bonding mode really selects a |
| 991 | transmit policy for an EtherChannel group; all three will interoperate |
| 992 | with another EtherChannel group. |
| 993 | |
| 994 | |
| 995 | 7. 802.1q VLAN Support |
| 996 | ====================== |
| 997 | |
| 998 | It is possible to configure VLAN devices over a bond interface |
| 999 | using the 8021q driver. However, only packets coming from the 8021q |
| 1000 | driver and passing through bonding will be tagged by default. Self |
| 1001 | generated packets, for example, bonding's learning packets or ARP |
| 1002 | packets generated by either ALB mode or the ARP monitor mechanism, are |
| 1003 | tagged internally by bonding itself. As a result, bonding must |
| 1004 | "learn" the VLAN IDs configured above it, and use those IDs to tag |
| 1005 | self generated packets. |
| 1006 | |
| 1007 | For reasons of simplicity, and to support the use of adapters |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1008 | that can do VLAN hardware acceleration offloading, the bonding |
| 1009 | interface declares itself as fully hardware offloading capable, it gets |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1010 | the add_vid/kill_vid notifications to gather the necessary |
| 1011 | information, and it propagates those actions to the slaves. In case |
| 1012 | of mixed adapter types, hardware accelerated tagged packets that |
| 1013 | should go through an adapter that is not offloading capable are |
| 1014 | "un-accelerated" by the bonding driver so the VLAN tag sits in the |
| 1015 | regular location. |
| 1016 | |
| 1017 | VLAN interfaces *must* be added on top of a bonding interface |
| 1018 | only after enslaving at least one slave. The bonding interface has a |
| 1019 | hardware address of 00:00:00:00:00:00 until the first slave is added. |
| 1020 | If the VLAN interface is created prior to the first enslavement, it |
| 1021 | would pick up the all-zeroes hardware address. Once the first slave |
| 1022 | is attached to the bond, the bond device itself will pick up the |
| 1023 | slave's hardware address, which is then available for the VLAN device. |
| 1024 | |
| 1025 | Also, be aware that a similar problem can occur if all slaves |
| 1026 | are released from a bond that still has one or more VLAN interfaces on |
| 1027 | top of it. When a new slave is added, the bonding interface will |
| 1028 | obtain its hardware address from the first slave, which might not |
| 1029 | match the hardware address of the VLAN interfaces (which was |
| 1030 | ultimately copied from an earlier slave). |
| 1031 | |
| 1032 | There are two methods to insure that the VLAN device operates |
| 1033 | with the correct hardware address if all slaves are removed from a |
| 1034 | bond interface: |
| 1035 | |
| 1036 | 1. Remove all VLAN interfaces then recreate them |
| 1037 | |
| 1038 | 2. Set the bonding interface's hardware address so that it |
| 1039 | matches the hardware address of the VLAN interfaces. |
| 1040 | |
| 1041 | Note that changing a VLAN interface's HW address would set the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1042 | underlying device -- i.e. the bonding interface -- to promiscuous |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1043 | mode, which might not be what you want. |
| 1044 | |
| 1045 | |
| 1046 | 8. Link Monitoring |
| 1047 | ================== |
| 1048 | |
| 1049 | The bonding driver at present supports two schemes for |
| 1050 | monitoring a slave device's link state: the ARP monitor and the MII |
| 1051 | monitor. |
| 1052 | |
| 1053 | At the present time, due to implementation restrictions in the |
| 1054 | bonding driver itself, it is not possible to enable both ARP and MII |
| 1055 | monitoring simultaneously. |
| 1056 | |
| 1057 | 8.1 ARP Monitor Operation |
| 1058 | ------------------------- |
| 1059 | |
| 1060 | The ARP monitor operates as its name suggests: it sends ARP |
| 1061 | queries to one or more designated peer systems on the network, and |
| 1062 | uses the response as an indication that the link is operating. This |
| 1063 | gives some assurance that traffic is actually flowing to and from one |
| 1064 | or more peers on the local network. |
| 1065 | |
| 1066 | The ARP monitor relies on the device driver itself to verify |
| 1067 | that traffic is flowing. In particular, the driver must keep up to |
| 1068 | date the last receive time, dev->last_rx, and transmit start time, |
| 1069 | dev->trans_start. If these are not updated by the driver, then the |
| 1070 | ARP monitor will immediately fail any slaves using that driver, and |
| 1071 | those slaves will stay down. If networking monitoring (tcpdump, etc) |
| 1072 | shows the ARP requests and replies on the network, then it may be that |
| 1073 | your device driver is not updating last_rx and trans_start. |
| 1074 | |
| 1075 | 8.2 Configuring Multiple ARP Targets |
| 1076 | ------------------------------------ |
| 1077 | |
| 1078 | While ARP monitoring can be done with just one target, it can |
| 1079 | be useful in a High Availability setup to have several targets to |
| 1080 | monitor. In the case of just one target, the target itself may go |
| 1081 | down or have a problem making it unresponsive to ARP requests. Having |
| 1082 | an additional target (or several) increases the reliability of the ARP |
| 1083 | monitoring. |
| 1084 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1085 | Multiple ARP targets must be separated by commas as follows: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1086 | |
| 1087 | # example options for ARP monitoring with three targets |
| 1088 | alias bond0 bonding |
| 1089 | options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9 |
| 1090 | |
| 1091 | For just a single target the options would resemble: |
| 1092 | |
| 1093 | # example options for ARP monitoring with one target |
| 1094 | alias bond0 bonding |
| 1095 | options bond0 arp_interval=60 arp_ip_target=192.168.0.100 |
| 1096 | |
| 1097 | |
| 1098 | 8.3 MII Monitor Operation |
| 1099 | ------------------------- |
| 1100 | |
| 1101 | The MII monitor monitors only the carrier state of the local |
| 1102 | network interface. It accomplishes this in one of three ways: by |
| 1103 | depending upon the device driver to maintain its carrier state, by |
| 1104 | querying the device's MII registers, or by making an ethtool query to |
| 1105 | the device. |
| 1106 | |
| 1107 | If the use_carrier module parameter is 1 (the default value), |
| 1108 | then the MII monitor will rely on the driver for carrier state |
| 1109 | information (via the netif_carrier subsystem). As explained in the |
| 1110 | use_carrier parameter information, above, if the MII monitor fails to |
| 1111 | detect carrier loss on the device (e.g., when the cable is physically |
| 1112 | disconnected), it may be that the driver does not support |
| 1113 | netif_carrier. |
| 1114 | |
| 1115 | If use_carrier is 0, then the MII monitor will first query the |
| 1116 | device's (via ioctl) MII registers and check the link state. If that |
| 1117 | request fails (not just that it returns carrier down), then the MII |
| 1118 | monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain |
| 1119 | the same information. If both methods fail (i.e., the driver either |
| 1120 | does not support or had some error in processing both the MII register |
| 1121 | and ethtool requests), then the MII monitor will assume the link is |
| 1122 | up. |
| 1123 | |
| 1124 | 9. Potential Sources of Trouble |
| 1125 | =============================== |
| 1126 | |
| 1127 | 9.1 Adventures in Routing |
| 1128 | ------------------------- |
| 1129 | |
| 1130 | When bonding is configured, it is important that the slave |
| 1131 | devices not have routes that supercede routes of the master (or, |
| 1132 | generally, not have routes at all). For example, suppose the bonding |
| 1133 | device bond0 has two slaves, eth0 and eth1, and the routing table is |
| 1134 | as follows: |
| 1135 | |
| 1136 | Kernel IP routing table |
| 1137 | Destination Gateway Genmask Flags MSS Window irtt Iface |
| 1138 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth0 |
| 1139 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth1 |
| 1140 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 bond0 |
| 1141 | 127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo |
| 1142 | |
| 1143 | This routing configuration will likely still update the |
| 1144 | receive/transmit times in the driver (needed by the ARP monitor), but |
| 1145 | may bypass the bonding driver (because outgoing traffic to, in this |
| 1146 | case, another host on network 10 would use eth0 or eth1 before bond0). |
| 1147 | |
| 1148 | The ARP monitor (and ARP itself) may become confused by this |
| 1149 | configuration, because ARP requests (generated by the ARP monitor) |
| 1150 | will be sent on one interface (bond0), but the corresponding reply |
| 1151 | will arrive on a different interface (eth0). This reply looks to ARP |
| 1152 | as an unsolicited ARP reply (because ARP matches replies on an |
| 1153 | interface basis), and is discarded. The MII monitor is not affected |
| 1154 | by the state of the routing table. |
| 1155 | |
| 1156 | The solution here is simply to insure that slaves do not have |
| 1157 | routes of their own, and if for some reason they must, those routes do |
| 1158 | not supercede routes of their master. This should generally be the |
| 1159 | case, but unusual configurations or errant manual or automatic static |
| 1160 | route additions may cause trouble. |
| 1161 | |
| 1162 | 9.2 Ethernet Device Renaming |
| 1163 | ---------------------------- |
| 1164 | |
| 1165 | On systems with network configuration scripts that do not |
| 1166 | associate physical devices directly with network interface names (so |
| 1167 | that the same physical device always has the same "ethX" name), it may |
| 1168 | be necessary to add some special logic to either /etc/modules.conf or |
| 1169 | /etc/modprobe.conf (depending upon which is installed on the system). |
| 1170 | |
| 1171 | For example, given a modules.conf containing the following: |
| 1172 | |
| 1173 | alias bond0 bonding |
| 1174 | options bond0 mode=some-mode miimon=50 |
| 1175 | alias eth0 tg3 |
| 1176 | alias eth1 tg3 |
| 1177 | alias eth2 e1000 |
| 1178 | alias eth3 e1000 |
| 1179 | |
| 1180 | If neither eth0 and eth1 are slaves to bond0, then when the |
| 1181 | bond0 interface comes up, the devices may end up reordered. This |
| 1182 | happens because bonding is loaded first, then its slave device's |
| 1183 | drivers are loaded next. Since no other drivers have been loaded, |
| 1184 | when the e1000 driver loads, it will receive eth0 and eth1 for its |
| 1185 | devices, but the bonding configuration tries to enslave eth2 and eth3 |
| 1186 | (which may later be assigned to the tg3 devices). |
| 1187 | |
| 1188 | Adding the following: |
| 1189 | |
| 1190 | add above bonding e1000 tg3 |
| 1191 | |
| 1192 | causes modprobe to load e1000 then tg3, in that order, when |
| 1193 | bonding is loaded. This command is fully documented in the |
| 1194 | modules.conf manual page. |
| 1195 | |
| 1196 | On systems utilizing modprobe.conf (or modprobe.conf.local), |
| 1197 | an equivalent problem can occur. In this case, the following can be |
| 1198 | added to modprobe.conf (or modprobe.conf.local, as appropriate), as |
| 1199 | follows (all on one line; it has been split here for clarity): |
| 1200 | |
| 1201 | install bonding /sbin/modprobe tg3; /sbin/modprobe e1000; |
| 1202 | /sbin/modprobe --ignore-install bonding |
| 1203 | |
| 1204 | This will, when loading the bonding module, rather than |
| 1205 | performing the normal action, instead execute the provided command. |
| 1206 | This command loads the device drivers in the order needed, then calls |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1207 | modprobe with --ignore-install to cause the normal action to then take |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1208 | place. Full documentation on this can be found in the modprobe.conf |
| 1209 | and modprobe manual pages. |
| 1210 | |
| 1211 | 9.3. Painfully Slow Or No Failed Link Detection By Miimon |
| 1212 | --------------------------------------------------------- |
| 1213 | |
| 1214 | By default, bonding enables the use_carrier option, which |
| 1215 | instructs bonding to trust the driver to maintain carrier state. |
| 1216 | |
| 1217 | As discussed in the options section, above, some drivers do |
| 1218 | not support the netif_carrier_on/_off link state tracking system. |
| 1219 | With use_carrier enabled, bonding will always see these links as up, |
| 1220 | regardless of their actual state. |
| 1221 | |
| 1222 | Additionally, other drivers do support netif_carrier, but do |
| 1223 | not maintain it in real time, e.g., only polling the link state at |
| 1224 | some fixed interval. In this case, miimon will detect failures, but |
| 1225 | only after some long period of time has expired. If it appears that |
| 1226 | miimon is very slow in detecting link failures, try specifying |
| 1227 | use_carrier=0 to see if that improves the failure detection time. If |
| 1228 | it does, then it may be that the driver checks the carrier state at a |
| 1229 | fixed interval, but does not cache the MII register values (so the |
| 1230 | use_carrier=0 method of querying the registers directly works). If |
| 1231 | use_carrier=0 does not improve the failover, then the driver may cache |
| 1232 | the registers, or the problem may be elsewhere. |
| 1233 | |
| 1234 | Also, remember that miimon only checks for the device's |
| 1235 | carrier state. It has no way to determine the state of devices on or |
| 1236 | beyond other ports of a switch, or if a switch is refusing to pass |
| 1237 | traffic while still maintaining carrier on. |
| 1238 | |
| 1239 | 10. SNMP agents |
| 1240 | =============== |
| 1241 | |
| 1242 | If running SNMP agents, the bonding driver should be loaded |
| 1243 | before any network drivers participating in a bond. This requirement |
Tobias Klauser | d533f67 | 2005-09-10 00:26:46 -0700 | [diff] [blame] | 1244 | is due to the interface index (ipAdEntIfIndex) being associated to |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1245 | the first interface found with a given IP address. That is, there is |
| 1246 | only one ipAdEntIfIndex for each IP address. For example, if eth0 and |
| 1247 | eth1 are slaves of bond0 and the driver for eth0 is loaded before the |
| 1248 | bonding driver, the interface for the IP address will be associated |
| 1249 | with the eth0 interface. This configuration is shown below, the IP |
| 1250 | address 192.168.1.1 has an interface index of 2 which indexes to eth0 |
| 1251 | in the ifDescr table (ifDescr.2). |
| 1252 | |
| 1253 | interfaces.ifTable.ifEntry.ifDescr.1 = lo |
| 1254 | interfaces.ifTable.ifEntry.ifDescr.2 = eth0 |
| 1255 | interfaces.ifTable.ifEntry.ifDescr.3 = eth1 |
| 1256 | interfaces.ifTable.ifEntry.ifDescr.4 = eth2 |
| 1257 | interfaces.ifTable.ifEntry.ifDescr.5 = eth3 |
| 1258 | interfaces.ifTable.ifEntry.ifDescr.6 = bond0 |
| 1259 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5 |
| 1260 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 |
| 1261 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4 |
| 1262 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 |
| 1263 | |
| 1264 | This problem is avoided by loading the bonding driver before |
| 1265 | any network drivers participating in a bond. Below is an example of |
| 1266 | loading the bonding driver first, the IP address 192.168.1.1 is |
| 1267 | correctly associated with ifDescr.2. |
| 1268 | |
| 1269 | interfaces.ifTable.ifEntry.ifDescr.1 = lo |
| 1270 | interfaces.ifTable.ifEntry.ifDescr.2 = bond0 |
| 1271 | interfaces.ifTable.ifEntry.ifDescr.3 = eth0 |
| 1272 | interfaces.ifTable.ifEntry.ifDescr.4 = eth1 |
| 1273 | interfaces.ifTable.ifEntry.ifDescr.5 = eth2 |
| 1274 | interfaces.ifTable.ifEntry.ifDescr.6 = eth3 |
| 1275 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6 |
| 1276 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 |
| 1277 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5 |
| 1278 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 |
| 1279 | |
| 1280 | While some distributions may not report the interface name in |
| 1281 | ifDescr, the association between the IP address and IfIndex remains |
| 1282 | and SNMP functions such as Interface_Scan_Next will report that |
| 1283 | association. |
| 1284 | |
| 1285 | 11. Promiscuous mode |
| 1286 | ==================== |
| 1287 | |
| 1288 | When running network monitoring tools, e.g., tcpdump, it is |
| 1289 | common to enable promiscuous mode on the device, so that all traffic |
| 1290 | is seen (instead of seeing only traffic destined for the local host). |
| 1291 | The bonding driver handles promiscuous mode changes to the bonding |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1292 | master device (e.g., bond0), and propagates the setting to the slave |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1293 | devices. |
| 1294 | |
| 1295 | For the balance-rr, balance-xor, broadcast, and 802.3ad modes, |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1296 | the promiscuous mode setting is propagated to all slaves. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1297 | |
| 1298 | For the active-backup, balance-tlb and balance-alb modes, the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1299 | promiscuous mode setting is propagated only to the active slave. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1300 | |
| 1301 | For balance-tlb mode, the active slave is the slave currently |
| 1302 | receiving inbound traffic. |
| 1303 | |
| 1304 | For balance-alb mode, the active slave is the slave used as a |
| 1305 | "primary." This slave is used for mode-specific control traffic, for |
| 1306 | sending to peers that are unassigned or if the load is unbalanced. |
| 1307 | |
| 1308 | For the active-backup, balance-tlb and balance-alb modes, when |
| 1309 | the active slave changes (e.g., due to a link failure), the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1310 | promiscuous setting will be propagated to the new active slave. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1311 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1312 | 12. Configuring Bonding for High Availability |
| 1313 | ============================================= |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1314 | |
| 1315 | High Availability refers to configurations that provide |
| 1316 | maximum network availability by having redundant or backup devices, |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1317 | links or switches between the host and the rest of the world. The |
| 1318 | goal is to provide the maximum availability of network connectivity |
| 1319 | (i.e., the network always works), even though other configurations |
| 1320 | could provide higher throughput. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1321 | |
| 1322 | 12.1 High Availability in a Single Switch Topology |
| 1323 | -------------------------------------------------- |
| 1324 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1325 | If two hosts (or a host and a single switch) are directly |
| 1326 | connected via multiple physical links, then there is no availability |
| 1327 | penalty to optimizing for maximum bandwidth. In this case, there is |
| 1328 | only one switch (or peer), so if it fails, there is no alternative |
| 1329 | access to fail over to. Additionally, the bonding load balance modes |
| 1330 | support link monitoring of their members, so if individual links fail, |
| 1331 | the load will be rebalanced across the remaining devices. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1332 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1333 | See Section 13, "Configuring Bonding for Maximum Throughput" |
| 1334 | for information on configuring bonding with one peer device. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1335 | |
| 1336 | 12.2 High Availability in a Multiple Switch Topology |
| 1337 | ---------------------------------------------------- |
| 1338 | |
| 1339 | With multiple switches, the configuration of bonding and the |
| 1340 | network changes dramatically. In multiple switch topologies, there is |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1341 | a trade off between network availability and usable bandwidth. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1342 | |
| 1343 | Below is a sample network, configured to maximize the |
| 1344 | availability of the network: |
| 1345 | |
| 1346 | | | |
| 1347 | |port3 port3| |
| 1348 | +-----+----+ +-----+----+ |
| 1349 | | |port2 ISL port2| | |
| 1350 | | switch A +--------------------------+ switch B | |
| 1351 | | | | | |
| 1352 | +-----+----+ +-----++---+ |
| 1353 | |port1 port1| |
| 1354 | | +-------+ | |
| 1355 | +-------------+ host1 +---------------+ |
| 1356 | eth0 +-------+ eth1 |
| 1357 | |
| 1358 | In this configuration, there is a link between the two |
| 1359 | switches (ISL, or inter switch link), and multiple ports connecting to |
| 1360 | the outside world ("port3" on each switch). There is no technical |
| 1361 | reason that this could not be extended to a third switch. |
| 1362 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1363 | 12.2.1 HA Bonding Mode Selection for Multiple Switch Topology |
| 1364 | ------------------------------------------------------------- |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1365 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1366 | In a topology such as the example above, the active-backup and |
| 1367 | broadcast modes are the only useful bonding modes when optimizing for |
| 1368 | availability; the other modes require all links to terminate on the |
| 1369 | same peer for them to behave rationally. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1370 | |
| 1371 | active-backup: This is generally the preferred mode, particularly if |
| 1372 | the switches have an ISL and play together well. If the |
| 1373 | network configuration is such that one switch is specifically |
| 1374 | a backup switch (e.g., has lower capacity, higher cost, etc), |
| 1375 | then the primary option can be used to insure that the |
| 1376 | preferred link is always used when it is available. |
| 1377 | |
| 1378 | broadcast: This mode is really a special purpose mode, and is suitable |
| 1379 | only for very specific needs. For example, if the two |
| 1380 | switches are not connected (no ISL), and the networks beyond |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1381 | them are totally independent. In this case, if it is |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1382 | necessary for some specific one-way traffic to reach both |
| 1383 | independent networks, then the broadcast mode may be suitable. |
| 1384 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1385 | 12.2.2 HA Link Monitoring Selection for Multiple Switch Topology |
| 1386 | ---------------------------------------------------------------- |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1387 | |
| 1388 | The choice of link monitoring ultimately depends upon your |
| 1389 | switch. If the switch can reliably fail ports in response to other |
| 1390 | failures, then either the MII or ARP monitors should work. For |
| 1391 | example, in the above example, if the "port3" link fails at the remote |
| 1392 | end, the MII monitor has no direct means to detect this. The ARP |
| 1393 | monitor could be configured with a target at the remote end of port3, |
| 1394 | thus detecting that failure without switch support. |
| 1395 | |
| 1396 | In general, however, in a multiple switch topology, the ARP |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1397 | monitor can provide a higher level of reliability in detecting end to |
| 1398 | end connectivity failures (which may be caused by the failure of any |
| 1399 | individual component to pass traffic for any reason). Additionally, |
| 1400 | the ARP monitor should be configured with multiple targets (at least |
| 1401 | one for each switch in the network). This will insure that, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1402 | regardless of which switch is active, the ARP monitor has a suitable |
| 1403 | target to query. |
| 1404 | |
| 1405 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1406 | 13. Configuring Bonding for Maximum Throughput |
| 1407 | ============================================== |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1408 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1409 | 13.1 Maximizing Throughput in a Single Switch Topology |
| 1410 | ------------------------------------------------------ |
| 1411 | |
| 1412 | In a single switch configuration, the best method to maximize |
| 1413 | throughput depends upon the application and network environment. The |
| 1414 | various load balancing modes each have strengths and weaknesses in |
| 1415 | different environments, as detailed below. |
| 1416 | |
| 1417 | For this discussion, we will break down the topologies into |
| 1418 | two categories. Depending upon the destination of most traffic, we |
| 1419 | categorize them into either "gatewayed" or "local" configurations. |
| 1420 | |
| 1421 | In a gatewayed configuration, the "switch" is acting primarily |
| 1422 | as a router, and the majority of traffic passes through this router to |
| 1423 | other networks. An example would be the following: |
| 1424 | |
| 1425 | |
| 1426 | +----------+ +----------+ |
| 1427 | | |eth0 port1| | to other networks |
| 1428 | | Host A +---------------------+ router +-------------------> |
| 1429 | | +---------------------+ | Hosts B and C are out |
| 1430 | | |eth1 port2| | here somewhere |
| 1431 | +----------+ +----------+ |
| 1432 | |
| 1433 | The router may be a dedicated router device, or another host |
| 1434 | acting as a gateway. For our discussion, the important point is that |
| 1435 | the majority of traffic from Host A will pass through the router to |
| 1436 | some other network before reaching its final destination. |
| 1437 | |
| 1438 | In a gatewayed network configuration, although Host A may |
| 1439 | communicate with many other systems, all of its traffic will be sent |
| 1440 | and received via one other peer on the local network, the router. |
| 1441 | |
| 1442 | Note that the case of two systems connected directly via |
| 1443 | multiple physical links is, for purposes of configuring bonding, the |
| 1444 | same as a gatewayed configuration. In that case, it happens that all |
| 1445 | traffic is destined for the "gateway" itself, not some other network |
| 1446 | beyond the gateway. |
| 1447 | |
| 1448 | In a local configuration, the "switch" is acting primarily as |
| 1449 | a switch, and the majority of traffic passes through this switch to |
| 1450 | reach other stations on the same network. An example would be the |
| 1451 | following: |
| 1452 | |
| 1453 | +----------+ +----------+ +--------+ |
| 1454 | | |eth0 port1| +-------+ Host B | |
| 1455 | | Host A +------------+ switch |port3 +--------+ |
| 1456 | | +------------+ | +--------+ |
| 1457 | | |eth1 port2| +------------------+ Host C | |
| 1458 | +----------+ +----------+port4 +--------+ |
| 1459 | |
| 1460 | |
| 1461 | Again, the switch may be a dedicated switch device, or another |
| 1462 | host acting as a gateway. For our discussion, the important point is |
| 1463 | that the majority of traffic from Host A is destined for other hosts |
| 1464 | on the same local network (Hosts B and C in the above example). |
| 1465 | |
| 1466 | In summary, in a gatewayed configuration, traffic to and from |
| 1467 | the bonded device will be to the same MAC level peer on the network |
| 1468 | (the gateway itself, i.e., the router), regardless of its final |
| 1469 | destination. In a local configuration, traffic flows directly to and |
| 1470 | from the final destinations, thus, each destination (Host B, Host C) |
| 1471 | will be addressed directly by their individual MAC addresses. |
| 1472 | |
| 1473 | This distinction between a gatewayed and a local network |
| 1474 | configuration is important because many of the load balancing modes |
| 1475 | available use the MAC addresses of the local network source and |
| 1476 | destination to make load balancing decisions. The behavior of each |
| 1477 | mode is described below. |
| 1478 | |
| 1479 | |
| 1480 | 13.1.1 MT Bonding Mode Selection for Single Switch Topology |
| 1481 | ----------------------------------------------------------- |
| 1482 | |
| 1483 | This configuration is the easiest to set up and to understand, |
| 1484 | although you will have to decide which bonding mode best suits your |
| 1485 | needs. The trade offs for each mode are detailed below: |
| 1486 | |
| 1487 | balance-rr: This mode is the only mode that will permit a single |
| 1488 | TCP/IP connection to stripe traffic across multiple |
| 1489 | interfaces. It is therefore the only mode that will allow a |
| 1490 | single TCP/IP stream to utilize more than one interface's |
| 1491 | worth of throughput. This comes at a cost, however: the |
| 1492 | striping often results in peer systems receiving packets out |
| 1493 | of order, causing TCP/IP's congestion control system to kick |
| 1494 | in, often by retransmitting segments. |
| 1495 | |
| 1496 | It is possible to adjust TCP/IP's congestion limits by |
| 1497 | altering the net.ipv4.tcp_reordering sysctl parameter. The |
| 1498 | usual default value is 3, and the maximum useful value is 127. |
| 1499 | For a four interface balance-rr bond, expect that a single |
| 1500 | TCP/IP stream will utilize no more than approximately 2.3 |
| 1501 | interface's worth of throughput, even after adjusting |
| 1502 | tcp_reordering. |
| 1503 | |
| 1504 | Note that this out of order delivery occurs when both the |
| 1505 | sending and receiving systems are utilizing a multiple |
| 1506 | interface bond. Consider a configuration in which a |
| 1507 | balance-rr bond feeds into a single higher capacity network |
| 1508 | channel (e.g., multiple 100Mb/sec ethernets feeding a single |
| 1509 | gigabit ethernet via an etherchannel capable switch). In this |
| 1510 | configuration, traffic sent from the multiple 100Mb devices to |
| 1511 | a destination connected to the gigabit device will not see |
| 1512 | packets out of order. However, traffic sent from the gigabit |
| 1513 | device to the multiple 100Mb devices may or may not see |
| 1514 | traffic out of order, depending upon the balance policy of the |
| 1515 | switch. Many switches do not support any modes that stripe |
| 1516 | traffic (instead choosing a port based upon IP or MAC level |
| 1517 | addresses); for those devices, traffic flowing from the |
| 1518 | gigabit device to the many 100Mb devices will only utilize one |
| 1519 | interface. |
| 1520 | |
| 1521 | If you are utilizing protocols other than TCP/IP, UDP for |
| 1522 | example, and your application can tolerate out of order |
| 1523 | delivery, then this mode can allow for single stream datagram |
| 1524 | performance that scales near linearly as interfaces are added |
| 1525 | to the bond. |
| 1526 | |
| 1527 | This mode requires the switch to have the appropriate ports |
| 1528 | configured for "etherchannel" or "trunking." |
| 1529 | |
| 1530 | active-backup: There is not much advantage in this network topology to |
| 1531 | the active-backup mode, as the inactive backup devices are all |
| 1532 | connected to the same peer as the primary. In this case, a |
| 1533 | load balancing mode (with link monitoring) will provide the |
| 1534 | same level of network availability, but with increased |
| 1535 | available bandwidth. On the plus side, active-backup mode |
| 1536 | does not require any configuration of the switch, so it may |
| 1537 | have value if the hardware available does not support any of |
| 1538 | the load balance modes. |
| 1539 | |
| 1540 | balance-xor: This mode will limit traffic such that packets destined |
| 1541 | for specific peers will always be sent over the same |
| 1542 | interface. Since the destination is determined by the MAC |
| 1543 | addresses involved, this mode works best in a "local" network |
| 1544 | configuration (as described above), with destinations all on |
| 1545 | the same local network. This mode is likely to be suboptimal |
| 1546 | if all your traffic is passed through a single router (i.e., a |
| 1547 | "gatewayed" network configuration, as described above). |
| 1548 | |
| 1549 | As with balance-rr, the switch ports need to be configured for |
| 1550 | "etherchannel" or "trunking." |
| 1551 | |
| 1552 | broadcast: Like active-backup, there is not much advantage to this |
| 1553 | mode in this type of network topology. |
| 1554 | |
| 1555 | 802.3ad: This mode can be a good choice for this type of network |
| 1556 | topology. The 802.3ad mode is an IEEE standard, so all peers |
| 1557 | that implement 802.3ad should interoperate well. The 802.3ad |
| 1558 | protocol includes automatic configuration of the aggregates, |
| 1559 | so minimal manual configuration of the switch is needed |
| 1560 | (typically only to designate that some set of devices is |
| 1561 | available for 802.3ad). The 802.3ad standard also mandates |
| 1562 | that frames be delivered in order (within certain limits), so |
| 1563 | in general single connections will not see misordering of |
| 1564 | packets. The 802.3ad mode does have some drawbacks: the |
| 1565 | standard mandates that all devices in the aggregate operate at |
| 1566 | the same speed and duplex. Also, as with all bonding load |
| 1567 | balance modes other than balance-rr, no single connection will |
| 1568 | be able to utilize more than a single interface's worth of |
| 1569 | bandwidth. |
| 1570 | |
| 1571 | Additionally, the linux bonding 802.3ad implementation |
| 1572 | distributes traffic by peer (using an XOR of MAC addresses), |
| 1573 | so in a "gatewayed" configuration, all outgoing traffic will |
| 1574 | generally use the same device. Incoming traffic may also end |
| 1575 | up on a single device, but that is dependent upon the |
| 1576 | balancing policy of the peer's 8023.ad implementation. In a |
| 1577 | "local" configuration, traffic will be distributed across the |
| 1578 | devices in the bond. |
| 1579 | |
| 1580 | Finally, the 802.3ad mode mandates the use of the MII monitor, |
| 1581 | therefore, the ARP monitor is not available in this mode. |
| 1582 | |
| 1583 | balance-tlb: The balance-tlb mode balances outgoing traffic by peer. |
| 1584 | Since the balancing is done according to MAC address, in a |
| 1585 | "gatewayed" configuration (as described above), this mode will |
| 1586 | send all traffic across a single device. However, in a |
| 1587 | "local" network configuration, this mode balances multiple |
| 1588 | local network peers across devices in a vaguely intelligent |
| 1589 | manner (not a simple XOR as in balance-xor or 802.3ad mode), |
| 1590 | so that mathematically unlucky MAC addresses (i.e., ones that |
| 1591 | XOR to the same value) will not all "bunch up" on a single |
| 1592 | interface. |
| 1593 | |
| 1594 | Unlike 802.3ad, interfaces may be of differing speeds, and no |
| 1595 | special switch configuration is required. On the down side, |
| 1596 | in this mode all incoming traffic arrives over a single |
| 1597 | interface, this mode requires certain ethtool support in the |
| 1598 | network device driver of the slave interfaces, and the ARP |
| 1599 | monitor is not available. |
| 1600 | |
| 1601 | balance-alb: This mode is everything that balance-tlb is, and more. |
| 1602 | It has all of the features (and restrictions) of balance-tlb, |
| 1603 | and will also balance incoming traffic from local network |
| 1604 | peers (as described in the Bonding Module Options section, |
| 1605 | above). |
| 1606 | |
| 1607 | The only additional down side to this mode is that the network |
| 1608 | device driver must support changing the hardware address while |
| 1609 | the device is open. |
| 1610 | |
| 1611 | 13.1.2 MT Link Monitoring for Single Switch Topology |
| 1612 | ---------------------------------------------------- |
| 1613 | |
| 1614 | The choice of link monitoring may largely depend upon which |
| 1615 | mode you choose to use. The more advanced load balancing modes do not |
| 1616 | support the use of the ARP monitor, and are thus restricted to using |
| 1617 | the MII monitor (which does not provide as high a level of end to end |
| 1618 | assurance as the ARP monitor). |
| 1619 | |
| 1620 | 13.2 Maximum Throughput in a Multiple Switch Topology |
| 1621 | ----------------------------------------------------- |
| 1622 | |
| 1623 | Multiple switches may be utilized to optimize for throughput |
| 1624 | when they are configured in parallel as part of an isolated network |
| 1625 | between two or more systems, for example: |
| 1626 | |
| 1627 | +-----------+ |
| 1628 | | Host A | |
| 1629 | +-+---+---+-+ |
| 1630 | | | | |
| 1631 | +--------+ | +---------+ |
| 1632 | | | | |
| 1633 | +------+---+ +-----+----+ +-----+----+ |
| 1634 | | Switch A | | Switch B | | Switch C | |
| 1635 | +------+---+ +-----+----+ +-----+----+ |
| 1636 | | | | |
| 1637 | +--------+ | +---------+ |
| 1638 | | | | |
| 1639 | +-+---+---+-+ |
| 1640 | | Host B | |
| 1641 | +-----------+ |
| 1642 | |
| 1643 | In this configuration, the switches are isolated from one |
| 1644 | another. One reason to employ a topology such as this is for an |
| 1645 | isolated network with many hosts (a cluster configured for high |
| 1646 | performance, for example), using multiple smaller switches can be more |
| 1647 | cost effective than a single larger switch, e.g., on a network with 24 |
| 1648 | hosts, three 24 port switches can be significantly less expensive than |
| 1649 | a single 72 port switch. |
| 1650 | |
| 1651 | If access beyond the network is required, an individual host |
| 1652 | can be equipped with an additional network device connected to an |
| 1653 | external network; this host then additionally acts as a gateway. |
| 1654 | |
| 1655 | 13.2.1 MT Bonding Mode Selection for Multiple Switch Topology |
| 1656 | ------------------------------------------------------------- |
| 1657 | |
| 1658 | In actual practice, the bonding mode typically employed in |
| 1659 | configurations of this type is balance-rr. Historically, in this |
| 1660 | network configuration, the usual caveats about out of order packet |
| 1661 | delivery are mitigated by the use of network adapters that do not do |
| 1662 | any kind of packet coalescing (via the use of NAPI, or because the |
| 1663 | device itself does not generate interrupts until some number of |
| 1664 | packets has arrived). When employed in this fashion, the balance-rr |
| 1665 | mode allows individual connections between two hosts to effectively |
| 1666 | utilize greater than one interface's bandwidth. |
| 1667 | |
| 1668 | 13.2.2 MT Link Monitoring for Multiple Switch Topology |
| 1669 | ------------------------------------------------------ |
| 1670 | |
| 1671 | Again, in actual practice, the MII monitor is most often used |
| 1672 | in this configuration, as performance is given preference over |
| 1673 | availability. The ARP monitor will function in this topology, but its |
| 1674 | advantages over the MII monitor are mitigated by the volume of probes |
| 1675 | needed as the number of systems involved grows (remember that each |
| 1676 | host in the network is configured with bonding). |
| 1677 | |
| 1678 | 14. Switch Behavior Issues |
| 1679 | ========================== |
| 1680 | |
| 1681 | 14.1 Link Establishment and Failover Delays |
| 1682 | ------------------------------------------- |
| 1683 | |
| 1684 | Some switches exhibit undesirable behavior with regard to the |
| 1685 | timing of link up and down reporting by the switch. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1686 | |
| 1687 | First, when a link comes up, some switches may indicate that |
| 1688 | the link is up (carrier available), but not pass traffic over the |
| 1689 | interface for some period of time. This delay is typically due to |
| 1690 | some type of autonegotiation or routing protocol, but may also occur |
| 1691 | during switch initialization (e.g., during recovery after a switch |
| 1692 | failure). If you find this to be a problem, specify an appropriate |
| 1693 | value to the updelay bonding module option to delay the use of the |
| 1694 | relevant interface(s). |
| 1695 | |
| 1696 | Second, some switches may "bounce" the link state one or more |
| 1697 | times while a link is changing state. This occurs most commonly while |
| 1698 | the switch is initializing. Again, an appropriate updelay value may |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1699 | help. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1700 | |
| 1701 | Note that when a bonding interface has no active links, the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1702 | driver will immediately reuse the first link that goes up, even if the |
| 1703 | updelay parameter has been specified (the updelay is ignored in this |
| 1704 | case). If there are slave interfaces waiting for the updelay timeout |
| 1705 | to expire, the interface that first went into that state will be |
| 1706 | immediately reused. This reduces down time of the network if the |
| 1707 | value of updelay has been overestimated, and since this occurs only in |
| 1708 | cases with no connectivity, there is no additional penalty for |
| 1709 | ignoring the updelay. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1710 | |
| 1711 | In addition to the concerns about switch timings, if your |
| 1712 | switches take a long time to go into backup mode, it may be desirable |
| 1713 | to not activate a backup interface immediately after a link goes down. |
| 1714 | Failover may be delayed via the downdelay bonding module option. |
| 1715 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1716 | 14.2 Duplicated Incoming Packets |
| 1717 | -------------------------------- |
| 1718 | |
| 1719 | It is not uncommon to observe a short burst of duplicated |
| 1720 | traffic when the bonding device is first used, or after it has been |
| 1721 | idle for some period of time. This is most easily observed by issuing |
| 1722 | a "ping" to some other host on the network, and noticing that the |
| 1723 | output from ping flags duplicates (typically one per slave). |
| 1724 | |
| 1725 | For example, on a bond in active-backup mode with five slaves |
| 1726 | all connected to one switch, the output may appear as follows: |
| 1727 | |
| 1728 | # ping -n 10.0.4.2 |
| 1729 | PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data. |
| 1730 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms |
| 1731 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) |
| 1732 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) |
| 1733 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) |
| 1734 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) |
| 1735 | 64 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms |
| 1736 | 64 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms |
| 1737 | 64 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms |
| 1738 | |
| 1739 | This is not due to an error in the bonding driver, rather, it |
| 1740 | is a side effect of how many switches update their MAC forwarding |
| 1741 | tables. Initially, the switch does not associate the MAC address in |
| 1742 | the packet with a particular switch port, and so it may send the |
| 1743 | traffic to all ports until its MAC forwarding table is updated. Since |
| 1744 | the interfaces attached to the bond may occupy multiple ports on a |
| 1745 | single switch, when the switch (temporarily) floods the traffic to all |
| 1746 | ports, the bond device receives multiple copies of the same packet |
| 1747 | (one per slave device). |
| 1748 | |
| 1749 | The duplicated packet behavior is switch dependent, some |
| 1750 | switches exhibit this, and some do not. On switches that display this |
| 1751 | behavior, it can be induced by clearing the MAC forwarding table (on |
| 1752 | most Cisco switches, the privileged command "clear mac address-table |
| 1753 | dynamic" will accomplish this). |
| 1754 | |
| 1755 | 15. Hardware Specific Considerations |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1756 | ==================================== |
| 1757 | |
| 1758 | This section contains additional information for configuring |
| 1759 | bonding on specific hardware platforms, or for interfacing bonding |
| 1760 | with particular switches or other devices. |
| 1761 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1762 | 15.1 IBM BladeCenter |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1763 | -------------------- |
| 1764 | |
| 1765 | This applies to the JS20 and similar systems. |
| 1766 | |
| 1767 | On the JS20 blades, the bonding driver supports only |
| 1768 | balance-rr, active-backup, balance-tlb and balance-alb modes. This is |
| 1769 | largely due to the network topology inside the BladeCenter, detailed |
| 1770 | below. |
| 1771 | |
| 1772 | JS20 network adapter information |
| 1773 | -------------------------------- |
| 1774 | |
| 1775 | All JS20s come with two Broadcom Gigabit Ethernet ports |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1776 | integrated on the planar (that's "motherboard" in IBM-speak). In the |
| 1777 | BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to |
| 1778 | I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2. |
| 1779 | An add-on Broadcom daughter card can be installed on a JS20 to provide |
| 1780 | two more Gigabit Ethernet ports. These ports, eth2 and eth3, are |
| 1781 | wired to I/O Modules 3 and 4, respectively. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1782 | |
| 1783 | Each I/O Module may contain either a switch or a passthrough |
| 1784 | module (which allows ports to be directly connected to an external |
| 1785 | switch). Some bonding modes require a specific BladeCenter internal |
| 1786 | network topology in order to function; these are detailed below. |
| 1787 | |
| 1788 | Additional BladeCenter-specific networking information can be |
| 1789 | found in two IBM Redbooks (www.ibm.com/redbooks): |
| 1790 | |
| 1791 | "IBM eServer BladeCenter Networking Options" |
| 1792 | "IBM eServer BladeCenter Layer 2-7 Network Switching" |
| 1793 | |
| 1794 | BladeCenter networking configuration |
| 1795 | ------------------------------------ |
| 1796 | |
| 1797 | Because a BladeCenter can be configured in a very large number |
| 1798 | of ways, this discussion will be confined to describing basic |
| 1799 | configurations. |
| 1800 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1801 | Normally, Ethernet Switch Modules (ESMs) are used in I/O |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1802 | modules 1 and 2. In this configuration, the eth0 and eth1 ports of a |
| 1803 | JS20 will be connected to different internal switches (in the |
| 1804 | respective I/O modules). |
| 1805 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1806 | A passthrough module (OPM or CPM, optical or copper, |
| 1807 | passthrough module) connects the I/O module directly to an external |
| 1808 | switch. By using PMs in I/O module #1 and #2, the eth0 and eth1 |
| 1809 | interfaces of a JS20 can be redirected to the outside world and |
| 1810 | connected to a common external switch. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1811 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1812 | Depending upon the mix of ESMs and PMs, the network will |
| 1813 | appear to bonding as either a single switch topology (all PMs) or as a |
| 1814 | multiple switch topology (one or more ESMs, zero or more PMs). It is |
| 1815 | also possible to connect ESMs together, resulting in a configuration |
| 1816 | much like the example in "High Availability in a Multiple Switch |
| 1817 | Topology," above. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1818 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1819 | Requirements for specific modes |
| 1820 | ------------------------------- |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1821 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1822 | The balance-rr mode requires the use of passthrough modules |
| 1823 | for devices in the bond, all connected to an common external switch. |
| 1824 | That switch must be configured for "etherchannel" or "trunking" on the |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1825 | appropriate ports, as is usual for balance-rr. |
| 1826 | |
| 1827 | The balance-alb and balance-tlb modes will function with |
| 1828 | either switch modules or passthrough modules (or a mix). The only |
| 1829 | specific requirement for these modes is that all network interfaces |
| 1830 | must be able to reach all destinations for traffic sent over the |
| 1831 | bonding device (i.e., the network must converge at some point outside |
| 1832 | the BladeCenter). |
| 1833 | |
| 1834 | The active-backup mode has no additional requirements. |
| 1835 | |
| 1836 | Link monitoring issues |
| 1837 | ---------------------- |
| 1838 | |
| 1839 | When an Ethernet Switch Module is in place, only the ARP |
| 1840 | monitor will reliably detect link loss to an external switch. This is |
| 1841 | nothing unusual, but examination of the BladeCenter cabinet would |
| 1842 | suggest that the "external" network ports are the ethernet ports for |
| 1843 | the system, when it fact there is a switch between these "external" |
| 1844 | ports and the devices on the JS20 system itself. The MII monitor is |
| 1845 | only able to detect link failures between the ESM and the JS20 system. |
| 1846 | |
| 1847 | When a passthrough module is in place, the MII monitor does |
| 1848 | detect failures to the "external" port, which is then directly |
| 1849 | connected to the JS20 system. |
| 1850 | |
| 1851 | Other concerns |
| 1852 | -------------- |
| 1853 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1854 | The Serial Over LAN (SoL) link is established over the primary |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1855 | ethernet (eth0) only, therefore, any loss of link to eth0 will result |
| 1856 | in losing your SoL connection. It will not fail over with other |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1857 | network traffic, as the SoL system is beyond the control of the |
| 1858 | bonding driver. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1859 | |
| 1860 | It may be desirable to disable spanning tree on the switch |
| 1861 | (either the internal Ethernet Switch Module, or an external switch) to |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1862 | avoid fail-over delay issues when using bonding. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1863 | |
| 1864 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1865 | 16. Frequently Asked Questions |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1866 | ============================== |
| 1867 | |
| 1868 | 1. Is it SMP safe? |
| 1869 | |
| 1870 | Yes. The old 2.0.xx channel bonding patch was not SMP safe. |
| 1871 | The new driver was designed to be SMP safe from the start. |
| 1872 | |
| 1873 | 2. What type of cards will work with it? |
| 1874 | |
| 1875 | Any Ethernet type cards (you can even mix cards - a Intel |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1876 | EtherExpress PRO/100 and a 3com 3c905b, for example). For most modes, |
| 1877 | devices need not be of the same speed. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1878 | |
| 1879 | 3. How many bonding devices can I have? |
| 1880 | |
| 1881 | There is no limit. |
| 1882 | |
| 1883 | 4. How many slaves can a bonding device have? |
| 1884 | |
| 1885 | This is limited only by the number of network interfaces Linux |
| 1886 | supports and/or the number of network cards you can place in your |
| 1887 | system. |
| 1888 | |
| 1889 | 5. What happens when a slave link dies? |
| 1890 | |
| 1891 | If link monitoring is enabled, then the failing device will be |
| 1892 | disabled. The active-backup mode will fail over to a backup link, and |
| 1893 | other modes will ignore the failed link. The link will continue to be |
| 1894 | monitored, and should it recover, it will rejoin the bond (in whatever |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1895 | manner is appropriate for the mode). See the sections on High |
| 1896 | Availability and the documentation for each mode for additional |
| 1897 | information. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1898 | |
| 1899 | Link monitoring can be enabled via either the miimon or |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1900 | arp_interval parameters (described in the module parameters section, |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1901 | above). In general, miimon monitors the carrier state as sensed by |
| 1902 | the underlying network device, and the arp monitor (arp_interval) |
| 1903 | monitors connectivity to another host on the local network. |
| 1904 | |
| 1905 | If no link monitoring is configured, the bonding driver will |
| 1906 | be unable to detect link failures, and will assume that all links are |
| 1907 | always available. This will likely result in lost packets, and a |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1908 | resulting degradation of performance. The precise performance loss |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1909 | depends upon the bonding mode and network configuration. |
| 1910 | |
| 1911 | 6. Can bonding be used for High Availability? |
| 1912 | |
| 1913 | Yes. See the section on High Availability for details. |
| 1914 | |
| 1915 | 7. Which switches/systems does it work with? |
| 1916 | |
| 1917 | The full answer to this depends upon the desired mode. |
| 1918 | |
| 1919 | In the basic balance modes (balance-rr and balance-xor), it |
| 1920 | works with any system that supports etherchannel (also called |
| 1921 | trunking). Most managed switches currently available have such |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1922 | support, and many unmanaged switches as well. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1923 | |
| 1924 | The advanced balance modes (balance-tlb and balance-alb) do |
| 1925 | not have special switch requirements, but do need device drivers that |
| 1926 | support specific features (described in the appropriate section under |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1927 | module parameters, above). |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1928 | |
| 1929 | In 802.3ad mode, it works with with systems that support IEEE |
| 1930 | 802.3ad Dynamic Link Aggregation. Most managed and many unmanaged |
| 1931 | switches currently available support 802.3ad. |
| 1932 | |
| 1933 | The active-backup mode should work with any Layer-II switch. |
| 1934 | |
| 1935 | 8. Where does a bonding device get its MAC address from? |
| 1936 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1937 | If not explicitly configured (with ifconfig or ip link), the |
| 1938 | MAC address of the bonding device is taken from its first slave |
| 1939 | device. This MAC address is then passed to all following slaves and |
Tobias Klauser | d533f67 | 2005-09-10 00:26:46 -0700 | [diff] [blame] | 1940 | remains persistent (even if the first slave is removed) until the |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1941 | bonding device is brought down or reconfigured. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1942 | |
| 1943 | If you wish to change the MAC address, you can set it with |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1944 | ifconfig or ip link: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1945 | |
| 1946 | # ifconfig bond0 hw ether 00:11:22:33:44:55 |
| 1947 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1948 | # ip link set bond0 address 66:77:88:99:aa:bb |
| 1949 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1950 | The MAC address can be also changed by bringing down/up the |
| 1951 | device and then changing its slaves (or their order): |
| 1952 | |
| 1953 | # ifconfig bond0 down ; modprobe -r bonding |
| 1954 | # ifconfig bond0 .... up |
| 1955 | # ifenslave bond0 eth... |
| 1956 | |
| 1957 | This method will automatically take the address from the next |
| 1958 | slave that is added. |
| 1959 | |
| 1960 | To restore your slaves' MAC addresses, you need to detach them |
| 1961 | from the bond (`ifenslave -d bond0 eth0'). The bonding driver will |
| 1962 | then restore the MAC addresses that the slaves had before they were |
| 1963 | enslaved. |
| 1964 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1965 | 16. Resources and Links |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1966 | ======================= |
| 1967 | |
| 1968 | The latest version of the bonding driver can be found in the latest |
| 1969 | version of the linux kernel, found on http://kernel.org |
| 1970 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1971 | The latest version of this document can be found in either the latest |
| 1972 | kernel source (named Documentation/networking/bonding.txt), or on the |
| 1973 | bonding sourceforge site: |
| 1974 | |
| 1975 | http://www.sourceforge.net/projects/bonding |
| 1976 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1977 | Discussions regarding the bonding driver take place primarily on the |
| 1978 | bonding-devel mailing list, hosted at sourceforge.net. If you have |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1979 | questions or problems, post them to the list. The list address is: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1980 | |
| 1981 | bonding-devel@lists.sourceforge.net |
| 1982 | |
Jay Vosburgh | 00354cf | 2005-07-21 12:18:02 -0700 | [diff] [blame] | 1983 | The administrative interface (to subscribe or unsubscribe) can |
| 1984 | be found at: |
| 1985 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1986 | https://lists.sourceforge.net/lists/listinfo/bonding-devel |
| 1987 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1988 | Donald Becker's Ethernet Drivers and diag programs may be found at : |
| 1989 | - http://www.scyld.com/network/ |
| 1990 | |
| 1991 | You will also find a lot of information regarding Ethernet, NWay, MII, |
| 1992 | etc. at www.scyld.com. |
| 1993 | |
| 1994 | -- END -- |