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2 | Linux Ethernet Bonding Driver HOWTO |
3 | ||
9a6c6867 | 4 | Latest update: 12 November 2007 |
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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 | |
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15 | Added Sysfs information: 2006/04/24 |
16 | - Mitch Williams <mitch.a.williams at intel.com> | |
1da177e4 | 17 | |
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18 | Introduction |
19 | ============ | |
20 | ||
21 | The Linux bonding driver provides a method for aggregating | |
22 | multiple network interfaces into a single logical "bonded" interface. | |
23 | The behavior of the bonded interfaces depends upon the mode; generally | |
24 | speaking, modes provide either hot standby or load balancing services. | |
25 | Additionally, link integrity monitoring may be performed. | |
1da177e4 | 26 | |
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27 | The bonding driver originally came from Donald Becker's |
28 | beowulf patches for kernel 2.0. It has changed quite a bit since, and | |
29 | the original tools from extreme-linux and beowulf sites will not work | |
30 | with this version of the driver. | |
1da177e4 | 31 | |
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32 | For new versions of the driver, updated userspace tools, and |
33 | who to ask for help, please follow the links at the end of this file. | |
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34 | |
35 | Table of Contents | |
36 | ================= | |
37 | ||
38 | 1. Bonding Driver Installation | |
39 | ||
40 | 2. Bonding Driver Options | |
41 | ||
42 | 3. Configuring Bonding Devices | |
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43 | 3.1 Configuration with Sysconfig Support |
44 | 3.1.1 Using DHCP with Sysconfig | |
45 | 3.1.2 Configuring Multiple Bonds with Sysconfig | |
46 | 3.2 Configuration with Initscripts Support | |
47 | 3.2.1 Using DHCP with Initscripts | |
48 | 3.2.2 Configuring Multiple Bonds with Initscripts | |
49 | 3.3 Configuring Bonding Manually with Ifenslave | |
00354cfb | 50 | 3.3.1 Configuring Multiple Bonds Manually |
6224e01d | 51 | 3.4 Configuring Bonding Manually via Sysfs |
1da177e4 | 52 | |
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53 | 4. Querying Bonding Configuration |
54 | 4.1 Bonding Configuration | |
55 | 4.2 Network Configuration | |
1da177e4 | 56 | |
6224e01d | 57 | 5. Switch Configuration |
1da177e4 | 58 | |
6224e01d | 59 | 6. 802.1q VLAN Support |
1da177e4 | 60 | |
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61 | 7. Link Monitoring |
62 | 7.1 ARP Monitor Operation | |
63 | 7.2 Configuring Multiple ARP Targets | |
64 | 7.3 MII Monitor Operation | |
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66 | 8. Potential Trouble Sources |
67 | 8.1 Adventures in Routing | |
68 | 8.2 Ethernet Device Renaming | |
69 | 8.3 Painfully Slow Or No Failed Link Detection By Miimon | |
1da177e4 | 70 | |
6224e01d | 71 | 9. SNMP agents |
1da177e4 | 72 | |
6224e01d | 73 | 10. Promiscuous mode |
1da177e4 | 74 | |
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75 | 11. Configuring Bonding for High Availability |
76 | 11.1 High Availability in a Single Switch Topology | |
77 | 11.2 High Availability in a Multiple Switch Topology | |
78 | 11.2.1 HA Bonding Mode Selection for Multiple Switch Topology | |
79 | 11.2.2 HA Link Monitoring for Multiple Switch Topology | |
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81 | 12. Configuring Bonding for Maximum Throughput |
82 | 12.1 Maximum Throughput in a Single Switch Topology | |
83 | 12.1.1 MT Bonding Mode Selection for Single Switch Topology | |
84 | 12.1.2 MT Link Monitoring for Single Switch Topology | |
85 | 12.2 Maximum Throughput in a Multiple Switch Topology | |
86 | 12.2.1 MT Bonding Mode Selection for Multiple Switch Topology | |
87 | 12.2.2 MT Link Monitoring for Multiple Switch Topology | |
1da177e4 | 88 | |
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89 | 13. Switch Behavior Issues |
90 | 13.1 Link Establishment and Failover Delays | |
91 | 13.2 Duplicated Incoming Packets | |
1da177e4 | 92 | |
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93 | 14. Hardware Specific Considerations |
94 | 14.1 IBM BladeCenter | |
1da177e4 | 95 | |
6224e01d | 96 | 15. Frequently Asked Questions |
00354cfb | 97 | |
6224e01d | 98 | 16. Resources and Links |
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99 | |
100 | ||
101 | 1. Bonding Driver Installation | |
102 | ============================== | |
103 | ||
104 | Most popular distro kernels ship with the bonding driver | |
105 | already available as a module and the ifenslave user level control | |
106 | program installed and ready for use. If your distro does not, or you | |
107 | have need to compile bonding from source (e.g., configuring and | |
108 | installing a mainline kernel from kernel.org), you'll need to perform | |
109 | the following steps: | |
110 | ||
111 | 1.1 Configure and build the kernel with bonding | |
112 | ----------------------------------------------- | |
113 | ||
00354cfb | 114 | The current version of the bonding driver is available in the |
1da177e4 | 115 | drivers/net/bonding subdirectory of the most recent kernel source |
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116 | (which is available on http://kernel.org). Most users "rolling their |
117 | own" will want to use the most recent kernel from kernel.org. | |
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118 | |
119 | Configure kernel with "make menuconfig" (or "make xconfig" or | |
120 | "make config"), then select "Bonding driver support" in the "Network | |
121 | device support" section. It is recommended that you configure the | |
122 | driver as module since it is currently the only way to pass parameters | |
123 | to the driver or configure more than one bonding device. | |
124 | ||
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125 | Build and install the new kernel and modules, then continue |
126 | below to install ifenslave. | |
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127 | |
128 | 1.2 Install ifenslave Control Utility | |
129 | ------------------------------------- | |
130 | ||
131 | The ifenslave user level control program is included in the | |
132 | kernel source tree, in the file Documentation/networking/ifenslave.c. | |
133 | It is generally recommended that you use the ifenslave that | |
134 | corresponds to the kernel that you are using (either from the same | |
135 | source tree or supplied with the distro), however, ifenslave | |
136 | executables from older kernels should function (but features newer | |
137 | than the ifenslave release are not supported). Running an ifenslave | |
138 | that is newer than the kernel is not supported, and may or may not | |
139 | work. | |
140 | ||
141 | To install ifenslave, do the following: | |
142 | ||
143 | # gcc -Wall -O -I/usr/src/linux/include ifenslave.c -o ifenslave | |
144 | # cp ifenslave /sbin/ifenslave | |
145 | ||
146 | If your kernel source is not in "/usr/src/linux," then replace | |
147 | "/usr/src/linux/include" in the above with the location of your kernel | |
148 | source include directory. | |
149 | ||
150 | You may wish to back up any existing /sbin/ifenslave, or, for | |
151 | testing or informal use, tag the ifenslave to the kernel version | |
152 | (e.g., name the ifenslave executable /sbin/ifenslave-2.6.10). | |
153 | ||
154 | IMPORTANT NOTE: | |
155 | ||
156 | If you omit the "-I" or specify an incorrect directory, you | |
157 | may end up with an ifenslave that is incompatible with the kernel | |
158 | you're trying to build it for. Some distros (e.g., Red Hat from 7.1 | |
159 | onwards) do not have /usr/include/linux symbolically linked to the | |
160 | default kernel source include directory. | |
161 | ||
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162 | SECOND IMPORTANT NOTE: |
163 | If you plan to configure bonding using sysfs, you do not need | |
164 | to use ifenslave. | |
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165 | |
166 | 2. Bonding Driver Options | |
167 | ========================= | |
168 | ||
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169 | Options for the bonding driver are supplied as parameters to the |
170 | bonding module at load time, or are specified via sysfs. | |
171 | ||
172 | Module options may be given as command line arguments to the | |
173 | insmod or modprobe command, but are usually specified in either the | |
174 | /etc/modules.conf or /etc/modprobe.conf configuration file, or in a | |
175 | distro-specific configuration file (some of which are detailed in the next | |
176 | section). | |
177 | ||
178 | Details on bonding support for sysfs is provided in the | |
179 | "Configuring Bonding Manually via Sysfs" section, below. | |
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180 | |
181 | The available bonding driver parameters are listed below. If a | |
182 | parameter is not specified the default value is used. When initially | |
183 | configuring a bond, it is recommended "tail -f /var/log/messages" be | |
184 | run in a separate window to watch for bonding driver error messages. | |
185 | ||
186 | It is critical that either the miimon or arp_interval and | |
187 | arp_ip_target parameters be specified, otherwise serious network | |
188 | degradation will occur during link failures. Very few devices do not | |
189 | support at least miimon, so there is really no reason not to use it. | |
190 | ||
191 | Options with textual values will accept either the text name | |
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192 | or, for backwards compatibility, the option value. E.g., |
193 | "mode=802.3ad" and "mode=4" set the same mode. | |
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194 | |
195 | The parameters are as follows: | |
196 | ||
197 | arp_interval | |
198 | ||
00354cfb | 199 | Specifies the ARP link monitoring frequency in milliseconds. |
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200 | |
201 | The ARP monitor works by periodically checking the slave | |
202 | devices to determine whether they have sent or received | |
203 | traffic recently (the precise criteria depends upon the | |
204 | bonding mode, and the state of the slave). Regular traffic is | |
205 | generated via ARP probes issued for the addresses specified by | |
206 | the arp_ip_target option. | |
207 | ||
208 | This behavior can be modified by the arp_validate option, | |
209 | below. | |
210 | ||
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211 | If ARP monitoring is used in an etherchannel compatible mode |
212 | (modes 0 and 2), the switch should be configured in a mode | |
213 | that evenly distributes packets across all links. If the | |
214 | switch is configured to distribute the packets in an XOR | |
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215 | fashion, all replies from the ARP targets will be received on |
216 | the same link which could cause the other team members to | |
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217 | fail. ARP monitoring should not be used in conjunction with |
218 | miimon. A value of 0 disables ARP monitoring. The default | |
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219 | value is 0. |
220 | ||
221 | arp_ip_target | |
222 | ||
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223 | Specifies the IP addresses to use as ARP monitoring peers when |
224 | arp_interval is > 0. These are the targets of the ARP request | |
225 | sent to determine the health of the link to the targets. | |
226 | Specify these values in ddd.ddd.ddd.ddd format. Multiple IP | |
227 | addresses must be separated by a comma. At least one IP | |
228 | address must be given for ARP monitoring to function. The | |
229 | maximum number of targets that can be specified is 16. The | |
230 | default value is no IP addresses. | |
1da177e4 | 231 | |
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232 | arp_validate |
233 | ||
234 | Specifies whether or not ARP probes and replies should be | |
235 | validated in the active-backup mode. This causes the ARP | |
236 | monitor to examine the incoming ARP requests and replies, and | |
237 | only consider a slave to be up if it is receiving the | |
238 | appropriate ARP traffic. | |
239 | ||
240 | Possible values are: | |
241 | ||
242 | none or 0 | |
243 | ||
244 | No validation is performed. This is the default. | |
245 | ||
246 | active or 1 | |
247 | ||
248 | Validation is performed only for the active slave. | |
249 | ||
250 | backup or 2 | |
251 | ||
252 | Validation is performed only for backup slaves. | |
253 | ||
254 | all or 3 | |
255 | ||
256 | Validation is performed for all slaves. | |
257 | ||
258 | For the active slave, the validation checks ARP replies to | |
259 | confirm that they were generated by an arp_ip_target. Since | |
260 | backup slaves do not typically receive these replies, the | |
261 | validation performed for backup slaves is on the ARP request | |
262 | sent out via the active slave. It is possible that some | |
263 | switch or network configurations may result in situations | |
264 | wherein the backup slaves do not receive the ARP requests; in | |
265 | such a situation, validation of backup slaves must be | |
266 | disabled. | |
267 | ||
268 | This option is useful in network configurations in which | |
269 | multiple bonding hosts are concurrently issuing ARPs to one or | |
270 | more targets beyond a common switch. Should the link between | |
271 | the switch and target fail (but not the switch itself), the | |
272 | probe traffic generated by the multiple bonding instances will | |
273 | fool the standard ARP monitor into considering the links as | |
274 | still up. Use of the arp_validate option can resolve this, as | |
275 | the ARP monitor will only consider ARP requests and replies | |
276 | associated with its own instance of bonding. | |
277 | ||
278 | This option was added in bonding version 3.1.0. | |
279 | ||
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280 | downdelay |
281 | ||
282 | Specifies the time, in milliseconds, to wait before disabling | |
283 | a slave after a link failure has been detected. This option | |
284 | is only valid for the miimon link monitor. The downdelay | |
285 | value should be a multiple of the miimon value; if not, it | |
286 | will be rounded down to the nearest multiple. The default | |
287 | value is 0. | |
288 | ||
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289 | fail_over_mac |
290 | ||
291 | Specifies whether active-backup mode should set all slaves to | |
292 | the same MAC address (the traditional behavior), or, when | |
293 | enabled, change the bond's MAC address when changing the | |
294 | active interface (i.e., fail over the MAC address itself). | |
295 | ||
296 | Fail over MAC is useful for devices that cannot ever alter | |
297 | their MAC address, or for devices that refuse incoming | |
298 | broadcasts with their own source MAC (which interferes with | |
299 | the ARP monitor). | |
300 | ||
301 | The down side of fail over MAC is that every device on the | |
302 | network must be updated via gratuitous ARP, vs. just updating | |
303 | a switch or set of switches (which often takes place for any | |
304 | traffic, not just ARP traffic, if the switch snoops incoming | |
305 | traffic to update its tables) for the traditional method. If | |
306 | the gratuitous ARP is lost, communication may be disrupted. | |
307 | ||
308 | When fail over MAC is used in conjuction with the mii monitor, | |
309 | devices which assert link up prior to being able to actually | |
310 | transmit and receive are particularly susecptible to loss of | |
311 | the gratuitous ARP, and an appropriate updelay setting may be | |
312 | required. | |
313 | ||
314 | A value of 0 disables fail over MAC, and is the default. A | |
315 | value of 1 enables fail over MAC. This option is enabled | |
316 | automatically if the first slave added cannot change its MAC | |
317 | address. This option may be modified via sysfs only when no | |
318 | slaves are present in the bond. | |
319 | ||
320 | This option was added in bonding version 3.2.0. | |
321 | ||
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322 | lacp_rate |
323 | ||
324 | Option specifying the rate in which we'll ask our link partner | |
325 | to transmit LACPDU packets in 802.3ad mode. Possible values | |
326 | are: | |
327 | ||
328 | slow or 0 | |
00354cfb | 329 | Request partner to transmit LACPDUs every 30 seconds |
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330 | |
331 | fast or 1 | |
332 | Request partner to transmit LACPDUs every 1 second | |
333 | ||
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334 | The default is slow. |
335 | ||
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336 | max_bonds |
337 | ||
338 | Specifies the number of bonding devices to create for this | |
339 | instance of the bonding driver. E.g., if max_bonds is 3, and | |
340 | the bonding driver is not already loaded, then bond0, bond1 | |
341 | and bond2 will be created. The default value is 1. | |
342 | ||
343 | miimon | |
344 | ||
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345 | Specifies the MII link monitoring frequency in milliseconds. |
346 | This determines how often the link state of each slave is | |
347 | inspected for link failures. A value of zero disables MII | |
348 | link monitoring. A value of 100 is a good starting point. | |
349 | The use_carrier option, below, affects how the link state is | |
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350 | determined. See the High Availability section for additional |
351 | information. The default value is 0. | |
352 | ||
353 | mode | |
354 | ||
355 | Specifies one of the bonding policies. The default is | |
356 | balance-rr (round robin). Possible values are: | |
357 | ||
358 | balance-rr or 0 | |
359 | ||
360 | Round-robin policy: Transmit packets in sequential | |
361 | order from the first available slave through the | |
362 | last. This mode provides load balancing and fault | |
363 | tolerance. | |
364 | ||
365 | active-backup or 1 | |
366 | ||
367 | Active-backup policy: Only one slave in the bond is | |
368 | active. A different slave becomes active if, and only | |
369 | if, the active slave fails. The bond's MAC address is | |
370 | externally visible on only one port (network adapter) | |
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371 | to avoid confusing the switch. |
372 | ||
373 | In bonding version 2.6.2 or later, when a failover | |
374 | occurs in active-backup mode, bonding will issue one | |
375 | or more gratuitous ARPs on the newly active slave. | |
6224e01d | 376 | One gratuitous ARP is issued for the bonding master |
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377 | interface and each VLAN interfaces configured above |
378 | it, provided that the interface has at least one IP | |
379 | address configured. Gratuitous ARPs issued for VLAN | |
380 | interfaces are tagged with the appropriate VLAN id. | |
381 | ||
382 | This mode provides fault tolerance. The primary | |
383 | option, documented below, affects the behavior of this | |
384 | mode. | |
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385 | |
386 | balance-xor or 2 | |
387 | ||
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388 | XOR policy: Transmit based on the selected transmit |
389 | hash policy. The default policy is a simple [(source | |
390 | MAC address XOR'd with destination MAC address) modulo | |
391 | slave count]. Alternate transmit policies may be | |
392 | selected via the xmit_hash_policy option, described | |
393 | below. | |
394 | ||
395 | This mode provides load balancing and fault tolerance. | |
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396 | |
397 | broadcast or 3 | |
398 | ||
399 | Broadcast policy: transmits everything on all slave | |
400 | interfaces. This mode provides fault tolerance. | |
401 | ||
402 | 802.3ad or 4 | |
403 | ||
404 | IEEE 802.3ad Dynamic link aggregation. Creates | |
405 | aggregation groups that share the same speed and | |
406 | duplex settings. Utilizes all slaves in the active | |
407 | aggregator according to the 802.3ad specification. | |
408 | ||
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409 | Slave selection for outgoing traffic is done according |
410 | to the transmit hash policy, which may be changed from | |
411 | the default simple XOR policy via the xmit_hash_policy | |
412 | option, documented below. Note that not all transmit | |
413 | policies may be 802.3ad compliant, particularly in | |
414 | regards to the packet mis-ordering requirements of | |
415 | section 43.2.4 of the 802.3ad standard. Differing | |
416 | peer implementations will have varying tolerances for | |
417 | noncompliance. | |
418 | ||
419 | Prerequisites: | |
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420 | |
421 | 1. Ethtool support in the base drivers for retrieving | |
422 | the speed and duplex of each slave. | |
423 | ||
424 | 2. A switch that supports IEEE 802.3ad Dynamic link | |
425 | aggregation. | |
426 | ||
427 | Most switches will require some type of configuration | |
428 | to enable 802.3ad mode. | |
429 | ||
430 | balance-tlb or 5 | |
431 | ||
432 | Adaptive transmit load balancing: channel bonding that | |
433 | does not require any special switch support. The | |
434 | outgoing traffic is distributed according to the | |
435 | current load (computed relative to the speed) on each | |
436 | slave. Incoming traffic is received by the current | |
437 | slave. If the receiving slave fails, another slave | |
438 | takes over the MAC address of the failed receiving | |
439 | slave. | |
440 | ||
441 | Prerequisite: | |
442 | ||
443 | Ethtool support in the base drivers for retrieving the | |
444 | speed of each slave. | |
445 | ||
446 | balance-alb or 6 | |
447 | ||
448 | Adaptive load balancing: includes balance-tlb plus | |
449 | receive load balancing (rlb) for IPV4 traffic, and | |
450 | does not require any special switch support. The | |
451 | receive load balancing is achieved by ARP negotiation. | |
452 | The bonding driver intercepts the ARP Replies sent by | |
453 | the local system on their way out and overwrites the | |
454 | source hardware address with the unique hardware | |
455 | address of one of the slaves in the bond such that | |
456 | different peers use different hardware addresses for | |
457 | the server. | |
458 | ||
459 | Receive traffic from connections created by the server | |
460 | is also balanced. When the local system sends an ARP | |
461 | Request the bonding driver copies and saves the peer's | |
462 | IP information from the ARP packet. When the ARP | |
463 | Reply arrives from the peer, its hardware address is | |
464 | retrieved and the bonding driver initiates an ARP | |
465 | reply to this peer assigning it to one of the slaves | |
466 | in the bond. A problematic outcome of using ARP | |
467 | negotiation for balancing is that each time that an | |
468 | ARP request is broadcast it uses the hardware address | |
469 | of the bond. Hence, peers learn the hardware address | |
470 | of the bond and the balancing of receive traffic | |
471 | collapses to the current slave. This is handled by | |
472 | sending updates (ARP Replies) to all the peers with | |
473 | their individually assigned hardware address such that | |
474 | the traffic is redistributed. Receive traffic is also | |
475 | redistributed when a new slave is added to the bond | |
476 | and when an inactive slave is re-activated. The | |
477 | receive load is distributed sequentially (round robin) | |
478 | among the group of highest speed slaves in the bond. | |
479 | ||
480 | When a link is reconnected or a new slave joins the | |
481 | bond the receive traffic is redistributed among all | |
00354cfb | 482 | active slaves in the bond by initiating ARP Replies |
6224e01d | 483 | with the selected MAC address to each of the |
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484 | clients. The updelay parameter (detailed below) must |
485 | be set to a value equal or greater than the switch's | |
486 | forwarding delay so that the ARP Replies sent to the | |
487 | peers will not be blocked by the switch. | |
488 | ||
489 | Prerequisites: | |
490 | ||
491 | 1. Ethtool support in the base drivers for retrieving | |
492 | the speed of each slave. | |
493 | ||
494 | 2. Base driver support for setting the hardware | |
495 | address of a device while it is open. This is | |
496 | required so that there will always be one slave in the | |
497 | team using the bond hardware address (the | |
498 | curr_active_slave) while having a unique hardware | |
499 | address for each slave in the bond. If the | |
500 | curr_active_slave fails its hardware address is | |
501 | swapped with the new curr_active_slave that was | |
502 | chosen. | |
503 | ||
504 | primary | |
505 | ||
506 | A string (eth0, eth2, etc) specifying which slave is the | |
507 | primary device. The specified device will always be the | |
508 | active slave while it is available. Only when the primary is | |
509 | off-line will alternate devices be used. This is useful when | |
510 | one slave is preferred over another, e.g., when one slave has | |
511 | higher throughput than another. | |
512 | ||
513 | The primary option is only valid for active-backup mode. | |
514 | ||
515 | updelay | |
516 | ||
517 | Specifies the time, in milliseconds, to wait before enabling a | |
518 | slave after a link recovery has been detected. This option is | |
519 | only valid for the miimon link monitor. The updelay value | |
520 | should be a multiple of the miimon value; if not, it will be | |
521 | rounded down to the nearest multiple. The default value is 0. | |
522 | ||
523 | use_carrier | |
524 | ||
525 | Specifies whether or not miimon should use MII or ETHTOOL | |
526 | ioctls vs. netif_carrier_ok() to determine the link | |
527 | status. The MII or ETHTOOL ioctls are less efficient and | |
528 | utilize a deprecated calling sequence within the kernel. The | |
529 | netif_carrier_ok() relies on the device driver to maintain its | |
530 | state with netif_carrier_on/off; at this writing, most, but | |
531 | not all, device drivers support this facility. | |
532 | ||
533 | If bonding insists that the link is up when it should not be, | |
534 | it may be that your network device driver does not support | |
535 | netif_carrier_on/off. The default state for netif_carrier is | |
536 | "carrier on," so if a driver does not support netif_carrier, | |
537 | it will appear as if the link is always up. In this case, | |
538 | setting use_carrier to 0 will cause bonding to revert to the | |
539 | MII / ETHTOOL ioctl method to determine the link state. | |
540 | ||
541 | A value of 1 enables the use of netif_carrier_ok(), a value of | |
542 | 0 will use the deprecated MII / ETHTOOL ioctls. The default | |
543 | value is 1. | |
544 | ||
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545 | xmit_hash_policy |
546 | ||
547 | Selects the transmit hash policy to use for slave selection in | |
548 | balance-xor and 802.3ad modes. Possible values are: | |
549 | ||
550 | layer2 | |
551 | ||
552 | Uses XOR of hardware MAC addresses to generate the | |
553 | hash. The formula is | |
554 | ||
555 | (source MAC XOR destination MAC) modulo slave count | |
556 | ||
557 | This algorithm will place all traffic to a particular | |
558 | network peer on the same slave. | |
559 | ||
560 | This algorithm is 802.3ad compliant. | |
561 | ||
6f6652be JV |
562 | layer2+3 |
563 | ||
564 | This policy uses a combination of layer2 and layer3 | |
565 | protocol information to generate the hash. | |
566 | ||
567 | Uses XOR of hardware MAC addresses and IP addresses to | |
568 | generate the hash. The formula is | |
569 | ||
570 | (((source IP XOR dest IP) AND 0xffff) XOR | |
571 | ( source MAC XOR destination MAC )) | |
572 | modulo slave count | |
573 | ||
574 | This algorithm will place all traffic to a particular | |
575 | network peer on the same slave. For non-IP traffic, | |
576 | the formula is the same as for the layer2 transmit | |
577 | hash policy. | |
578 | ||
579 | This policy is intended to provide a more balanced | |
580 | distribution of traffic than layer2 alone, especially | |
581 | in environments where a layer3 gateway device is | |
582 | required to reach most destinations. | |
583 | ||
584 | This algorithm is 802.3ad complient. | |
585 | ||
00354cfb JV |
586 | layer3+4 |
587 | ||
588 | This policy uses upper layer protocol information, | |
589 | when available, to generate the hash. This allows for | |
590 | traffic to a particular network peer to span multiple | |
591 | slaves, although a single connection will not span | |
592 | multiple slaves. | |
593 | ||
594 | The formula for unfragmented TCP and UDP packets is | |
595 | ||
596 | ((source port XOR dest port) XOR | |
597 | ((source IP XOR dest IP) AND 0xffff) | |
598 | modulo slave count | |
599 | ||
600 | For fragmented TCP or UDP packets and all other IP | |
601 | protocol traffic, the source and destination port | |
602 | information is omitted. For non-IP traffic, the | |
603 | formula is the same as for the layer2 transmit hash | |
604 | policy. | |
605 | ||
606 | This policy is intended to mimic the behavior of | |
607 | certain switches, notably Cisco switches with PFC2 as | |
608 | well as some Foundry and IBM products. | |
609 | ||
610 | This algorithm is not fully 802.3ad compliant. A | |
611 | single TCP or UDP conversation containing both | |
612 | fragmented and unfragmented packets will see packets | |
613 | striped across two interfaces. This may result in out | |
614 | of order delivery. Most traffic types will not meet | |
615 | this criteria, as TCP rarely fragments traffic, and | |
616 | most UDP traffic is not involved in extended | |
617 | conversations. Other implementations of 802.3ad may | |
618 | or may not tolerate this noncompliance. | |
619 | ||
620 | The default value is layer2. This option was added in bonding | |
6f6652be JV |
621 | version 2.6.3. In earlier versions of bonding, this parameter |
622 | does not exist, and the layer2 policy is the only policy. The | |
623 | layer2+3 value was added for bonding version 3.2.2. | |
1da177e4 LT |
624 | |
625 | ||
626 | 3. Configuring Bonding Devices | |
627 | ============================== | |
628 | ||
6224e01d AK |
629 | You can configure bonding using either your distro's network |
630 | initialization scripts, or manually using either ifenslave or the | |
631 | sysfs interface. Distros generally use one of two packages for the | |
632 | network initialization scripts: initscripts or sysconfig. Recent | |
633 | versions of these packages have support for bonding, while older | |
634 | versions do not. | |
1da177e4 LT |
635 | |
636 | We will first describe the options for configuring bonding for | |
637 | distros using versions of initscripts and sysconfig with full or | |
638 | partial support for bonding, then provide information on enabling | |
639 | bonding without support from the network initialization scripts (i.e., | |
640 | older versions of initscripts or sysconfig). | |
641 | ||
642 | If you're unsure whether your distro uses sysconfig or | |
643 | initscripts, or don't know if it's new enough, have no fear. | |
644 | Determining this is fairly straightforward. | |
645 | ||
646 | First, issue the command: | |
647 | ||
648 | $ rpm -qf /sbin/ifup | |
649 | ||
650 | It will respond with a line of text starting with either | |
651 | "initscripts" or "sysconfig," followed by some numbers. This is the | |
652 | package that provides your network initialization scripts. | |
653 | ||
654 | Next, to determine if your installation supports bonding, | |
655 | issue the command: | |
656 | ||
657 | $ grep ifenslave /sbin/ifup | |
658 | ||
659 | If this returns any matches, then your initscripts or | |
660 | sysconfig has support for bonding. | |
661 | ||
6224e01d | 662 | 3.1 Configuration with Sysconfig Support |
1da177e4 LT |
663 | ---------------------------------------- |
664 | ||
665 | This section applies to distros using a version of sysconfig | |
666 | with bonding support, for example, SuSE Linux Enterprise Server 9. | |
667 | ||
668 | SuSE SLES 9's networking configuration system does support | |
669 | bonding, however, at this writing, the YaST system configuration | |
6224e01d | 670 | front end does not provide any means to work with bonding devices. |
1da177e4 LT |
671 | Bonding devices can be managed by hand, however, as follows. |
672 | ||
673 | First, if they have not already been configured, configure the | |
674 | slave devices. On SLES 9, this is most easily done by running the | |
675 | yast2 sysconfig configuration utility. The goal is for to create an | |
676 | ifcfg-id file for each slave device. The simplest way to accomplish | |
00354cfb JV |
677 | this is to configure the devices for DHCP (this is only to get the |
678 | file ifcfg-id file created; see below for some issues with DHCP). The | |
679 | name of the configuration file for each device will be of the form: | |
1da177e4 LT |
680 | |
681 | ifcfg-id-xx:xx:xx:xx:xx:xx | |
682 | ||
683 | Where the "xx" portion will be replaced with the digits from | |
684 | the device's permanent MAC address. | |
685 | ||
686 | Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been | |
687 | created, it is necessary to edit the configuration files for the slave | |
688 | devices (the MAC addresses correspond to those of the slave devices). | |
00354cfb | 689 | Before editing, the file will contain multiple lines, and will look |
1da177e4 LT |
690 | something like this: |
691 | ||
692 | BOOTPROTO='dhcp' | |
693 | STARTMODE='on' | |
694 | USERCTL='no' | |
695 | UNIQUE='XNzu.WeZGOGF+4wE' | |
696 | _nm_name='bus-pci-0001:61:01.0' | |
697 | ||
698 | Change the BOOTPROTO and STARTMODE lines to the following: | |
699 | ||
700 | BOOTPROTO='none' | |
701 | STARTMODE='off' | |
702 | ||
703 | Do not alter the UNIQUE or _nm_name lines. Remove any other | |
704 | lines (USERCTL, etc). | |
705 | ||
706 | Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified, | |
707 | it's time to create the configuration file for the bonding device | |
708 | itself. This file is named ifcfg-bondX, where X is the number of the | |
709 | bonding device to create, starting at 0. The first such file is | |
710 | ifcfg-bond0, the second is ifcfg-bond1, and so on. The sysconfig | |
711 | network configuration system will correctly start multiple instances | |
712 | of bonding. | |
713 | ||
714 | The contents of the ifcfg-bondX file is as follows: | |
715 | ||
716 | BOOTPROTO="static" | |
717 | BROADCAST="10.0.2.255" | |
718 | IPADDR="10.0.2.10" | |
719 | NETMASK="255.255.0.0" | |
720 | NETWORK="10.0.2.0" | |
721 | REMOTE_IPADDR="" | |
722 | STARTMODE="onboot" | |
723 | BONDING_MASTER="yes" | |
724 | BONDING_MODULE_OPTS="mode=active-backup miimon=100" | |
725 | BONDING_SLAVE0="eth0" | |
00354cfb | 726 | BONDING_SLAVE1="bus-pci-0000:06:08.1" |
1da177e4 LT |
727 | |
728 | Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK | |
729 | values with the appropriate values for your network. | |
730 | ||
1da177e4 LT |
731 | The STARTMODE specifies when the device is brought online. |
732 | The possible values are: | |
733 | ||
734 | onboot: The device is started at boot time. If you're not | |
735 | sure, this is probably what you want. | |
736 | ||
737 | manual: The device is started only when ifup is called | |
738 | manually. Bonding devices may be configured this | |
739 | way if you do not wish them to start automatically | |
740 | at boot for some reason. | |
741 | ||
742 | hotplug: The device is started by a hotplug event. This is not | |
743 | a valid choice for a bonding device. | |
744 | ||
745 | off or ignore: The device configuration is ignored. | |
746 | ||
747 | The line BONDING_MASTER='yes' indicates that the device is a | |
748 | bonding master device. The only useful value is "yes." | |
749 | ||
750 | The contents of BONDING_MODULE_OPTS are supplied to the | |
751 | instance of the bonding module for this device. Specify the options | |
752 | for the bonding mode, link monitoring, and so on here. Do not include | |
753 | the max_bonds bonding parameter; this will confuse the configuration | |
754 | system if you have multiple bonding devices. | |
755 | ||
00354cfb JV |
756 | Finally, supply one BONDING_SLAVEn="slave device" for each |
757 | slave. where "n" is an increasing value, one for each slave. The | |
758 | "slave device" is either an interface name, e.g., "eth0", or a device | |
759 | specifier for the network device. The interface name is easier to | |
760 | find, but the ethN names are subject to change at boot time if, e.g., | |
761 | a device early in the sequence has failed. The device specifiers | |
762 | (bus-pci-0000:06:08.1 in the example above) specify the physical | |
763 | network device, and will not change unless the device's bus location | |
764 | changes (for example, it is moved from one PCI slot to another). The | |
765 | example above uses one of each type for demonstration purposes; most | |
766 | configurations will choose one or the other for all slave devices. | |
1da177e4 LT |
767 | |
768 | When all configuration files have been modified or created, | |
769 | networking must be restarted for the configuration changes to take | |
770 | effect. This can be accomplished via the following: | |
771 | ||
772 | # /etc/init.d/network restart | |
773 | ||
774 | Note that the network control script (/sbin/ifdown) will | |
775 | remove the bonding module as part of the network shutdown processing, | |
776 | so it is not necessary to remove the module by hand if, e.g., the | |
00354cfb | 777 | module parameters have changed. |
1da177e4 LT |
778 | |
779 | Also, at this writing, YaST/YaST2 will not manage bonding | |
780 | devices (they do not show bonding interfaces on its list of network | |
781 | devices). It is necessary to edit the configuration file by hand to | |
782 | change the bonding configuration. | |
783 | ||
784 | Additional general options and details of the ifcfg file | |
785 | format can be found in an example ifcfg template file: | |
786 | ||
787 | /etc/sysconfig/network/ifcfg.template | |
788 | ||
789 | Note that the template does not document the various BONDING_ | |
790 | settings described above, but does describe many of the other options. | |
791 | ||
6224e01d | 792 | 3.1.1 Using DHCP with Sysconfig |
00354cfb JV |
793 | ------------------------------- |
794 | ||
795 | Under sysconfig, configuring a device with BOOTPROTO='dhcp' | |
796 | will cause it to query DHCP for its IP address information. At this | |
797 | writing, this does not function for bonding devices; the scripts | |
798 | attempt to obtain the device address from DHCP prior to adding any of | |
799 | the slave devices. Without active slaves, the DHCP requests are not | |
800 | sent to the network. | |
801 | ||
6224e01d | 802 | 3.1.2 Configuring Multiple Bonds with Sysconfig |
00354cfb JV |
803 | ----------------------------------------------- |
804 | ||
805 | The sysconfig network initialization system is capable of | |
806 | handling multiple bonding devices. All that is necessary is for each | |
807 | bonding instance to have an appropriately configured ifcfg-bondX file | |
808 | (as described above). Do not specify the "max_bonds" parameter to any | |
809 | instance of bonding, as this will confuse sysconfig. If you require | |
810 | multiple bonding devices with identical parameters, create multiple | |
811 | ifcfg-bondX files. | |
812 | ||
813 | Because the sysconfig scripts supply the bonding module | |
814 | options in the ifcfg-bondX file, it is not necessary to add them to | |
815 | the system /etc/modules.conf or /etc/modprobe.conf configuration file. | |
816 | ||
6224e01d | 817 | 3.2 Configuration with Initscripts Support |
1da177e4 LT |
818 | ------------------------------------------ |
819 | ||
9a6c6867 JV |
820 | This section applies to distros using a recent version of |
821 | initscripts with bonding support, for example, Red Hat Enterprise Linux | |
822 | version 3 or later, Fedora, etc. On these systems, the network | |
823 | initialization scripts have knowledge of bonding, and can be configured to | |
824 | control bonding devices. Note that older versions of the initscripts | |
825 | package have lower levels of support for bonding; this will be noted where | |
826 | applicable. | |
1da177e4 LT |
827 | |
828 | These distros will not automatically load the network adapter | |
829 | driver unless the ethX device is configured with an IP address. | |
830 | Because of this constraint, users must manually configure a | |
831 | network-script file for all physical adapters that will be members of | |
832 | a bondX link. Network script files are located in the directory: | |
833 | ||
834 | /etc/sysconfig/network-scripts | |
835 | ||
836 | The file name must be prefixed with "ifcfg-eth" and suffixed | |
837 | with the adapter's physical adapter number. For example, the script | |
838 | for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0. | |
839 | Place the following text in the file: | |
840 | ||
841 | DEVICE=eth0 | |
842 | USERCTL=no | |
843 | ONBOOT=yes | |
844 | MASTER=bond0 | |
845 | SLAVE=yes | |
846 | BOOTPROTO=none | |
847 | ||
848 | The DEVICE= line will be different for every ethX device and | |
849 | must correspond with the name of the file, i.e., ifcfg-eth1 must have | |
850 | a device line of DEVICE=eth1. The setting of the MASTER= line will | |
851 | also depend on the final bonding interface name chosen for your bond. | |
852 | As with other network devices, these typically start at 0, and go up | |
853 | one for each device, i.e., the first bonding instance is bond0, the | |
854 | second is bond1, and so on. | |
855 | ||
856 | Next, create a bond network script. The file name for this | |
857 | script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is | |
858 | the number of the bond. For bond0 the file is named "ifcfg-bond0", | |
859 | for bond1 it is named "ifcfg-bond1", and so on. Within that file, | |
860 | place the following text: | |
861 | ||
862 | DEVICE=bond0 | |
863 | IPADDR=192.168.1.1 | |
864 | NETMASK=255.255.255.0 | |
865 | NETWORK=192.168.1.0 | |
866 | BROADCAST=192.168.1.255 | |
867 | ONBOOT=yes | |
868 | BOOTPROTO=none | |
869 | USERCTL=no | |
870 | ||
871 | Be sure to change the networking specific lines (IPADDR, | |
872 | NETMASK, NETWORK and BROADCAST) to match your network configuration. | |
873 | ||
9a6c6867 JV |
874 | For later versions of initscripts, such as that found with Fedora |
875 | 7 and Red Hat Enterprise Linux version 5 (or later), it is possible, and, | |
876 | indeed, preferable, to specify the bonding options in the ifcfg-bond0 | |
877 | file, e.g. a line of the format: | |
878 | ||
879 | BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=+192.168.1.254" | |
880 | ||
881 | will configure the bond with the specified options. The options | |
882 | specified in BONDING_OPTS are identical to the bonding module parameters | |
883 | except for the arp_ip_target field. Each target should be included as a | |
884 | separate option and should be preceded by a '+' to indicate it should be | |
885 | added to the list of queried targets, e.g., | |
886 | ||
887 | arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2 | |
888 | ||
889 | is the proper syntax to specify multiple targets. When specifying | |
890 | options via BONDING_OPTS, it is not necessary to edit /etc/modules.conf or | |
891 | /etc/modprobe.conf. | |
892 | ||
893 | For older versions of initscripts that do not support | |
894 | BONDING_OPTS, it is necessary to edit /etc/modules.conf (or | |
895 | /etc/modprobe.conf, depending upon your distro) to load the bonding module | |
896 | with your desired options when the bond0 interface is brought up. The | |
897 | following lines in /etc/modules.conf (or modprobe.conf) will load the | |
898 | bonding module, and select its options: | |
1da177e4 LT |
899 | |
900 | alias bond0 bonding | |
901 | options bond0 mode=balance-alb miimon=100 | |
902 | ||
903 | Replace the sample parameters with the appropriate set of | |
904 | options for your configuration. | |
905 | ||
906 | Finally run "/etc/rc.d/init.d/network restart" as root. This | |
907 | will restart the networking subsystem and your bond link should be now | |
908 | up and running. | |
909 | ||
6224e01d | 910 | 3.2.1 Using DHCP with Initscripts |
00354cfb JV |
911 | --------------------------------- |
912 | ||
9a6c6867 JV |
913 | Recent versions of initscripts (the versions supplied with Fedora |
914 | Core 3 and Red Hat Enterprise Linux 4, or later versions, are reported to | |
915 | work) have support for assigning IP information to bonding devices via | |
916 | DHCP. | |
00354cfb JV |
917 | |
918 | To configure bonding for DHCP, configure it as described | |
919 | above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp" | |
920 | and add a line consisting of "TYPE=Bonding". Note that the TYPE value | |
921 | is case sensitive. | |
922 | ||
6224e01d | 923 | 3.2.2 Configuring Multiple Bonds with Initscripts |
00354cfb JV |
924 | ------------------------------------------------- |
925 | ||
9a6c6867 JV |
926 | Initscripts packages that are included with Fedora 7 and Red Hat |
927 | Enterprise Linux 5 support multiple bonding interfaces by simply | |
928 | specifying the appropriate BONDING_OPTS= in ifcfg-bondX where X is the | |
929 | number of the bond. This support requires sysfs support in the kernel, | |
930 | and a bonding driver of version 3.0.0 or later. Other configurations may | |
931 | not support this method for specifying multiple bonding interfaces; for | |
932 | those instances, see the "Configuring Multiple Bonds Manually" section, | |
933 | below. | |
1da177e4 | 934 | |
6224e01d AK |
935 | 3.3 Configuring Bonding Manually with Ifenslave |
936 | ----------------------------------------------- | |
1da177e4 LT |
937 | |
938 | This section applies to distros whose network initialization | |
939 | scripts (the sysconfig or initscripts package) do not have specific | |
940 | knowledge of bonding. One such distro is SuSE Linux Enterprise Server | |
941 | version 8. | |
942 | ||
00354cfb JV |
943 | The general method for these systems is to place the bonding |
944 | module parameters into /etc/modules.conf or /etc/modprobe.conf (as | |
945 | appropriate for the installed distro), then add modprobe and/or | |
946 | ifenslave commands to the system's global init script. The name of | |
947 | the global init script differs; for sysconfig, it is | |
1da177e4 LT |
948 | /etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local. |
949 | ||
950 | For example, if you wanted to make a simple bond of two e100 | |
951 | devices (presumed to be eth0 and eth1), and have it persist across | |
952 | reboots, edit the appropriate file (/etc/init.d/boot.local or | |
953 | /etc/rc.d/rc.local), and add the following: | |
954 | ||
00354cfb | 955 | modprobe bonding mode=balance-alb miimon=100 |
1da177e4 LT |
956 | modprobe e100 |
957 | ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up | |
958 | ifenslave bond0 eth0 | |
959 | ifenslave bond0 eth1 | |
960 | ||
961 | Replace the example bonding module parameters and bond0 | |
962 | network configuration (IP address, netmask, etc) with the appropriate | |
00354cfb | 963 | values for your configuration. |
1da177e4 LT |
964 | |
965 | Unfortunately, this method will not provide support for the | |
966 | ifup and ifdown scripts on the bond devices. To reload the bonding | |
967 | configuration, it is necessary to run the initialization script, e.g., | |
968 | ||
969 | # /etc/init.d/boot.local | |
970 | ||
971 | or | |
972 | ||
973 | # /etc/rc.d/rc.local | |
974 | ||
975 | It may be desirable in such a case to create a separate script | |
976 | which only initializes the bonding configuration, then call that | |
977 | separate script from within boot.local. This allows for bonding to be | |
978 | enabled without re-running the entire global init script. | |
979 | ||
980 | To shut down the bonding devices, it is necessary to first | |
981 | mark the bonding device itself as being down, then remove the | |
982 | appropriate device driver modules. For our example above, you can do | |
983 | the following: | |
984 | ||
985 | # ifconfig bond0 down | |
00354cfb | 986 | # rmmod bonding |
1da177e4 LT |
987 | # rmmod e100 |
988 | ||
989 | Again, for convenience, it may be desirable to create a script | |
990 | with these commands. | |
991 | ||
992 | ||
00354cfb JV |
993 | 3.3.1 Configuring Multiple Bonds Manually |
994 | ----------------------------------------- | |
1da177e4 LT |
995 | |
996 | This section contains information on configuring multiple | |
00354cfb JV |
997 | bonding devices with differing options for those systems whose network |
998 | initialization scripts lack support for configuring multiple bonds. | |
999 | ||
1000 | If you require multiple bonding devices, but all with the same | |
1001 | options, you may wish to use the "max_bonds" module parameter, | |
1002 | documented above. | |
1da177e4 | 1003 | |
9a6c6867 JV |
1004 | To create multiple bonding devices with differing options, it is |
1005 | preferrable to use bonding parameters exported by sysfs, documented in the | |
1006 | section below. | |
1007 | ||
1008 | For versions of bonding without sysfs support, the only means to | |
1009 | provide multiple instances of bonding with differing options is to load | |
1010 | the bonding driver multiple times. Note that current versions of the | |
1011 | sysconfig network initialization scripts handle this automatically; if | |
1012 | your distro uses these scripts, no special action is needed. See the | |
1013 | section Configuring Bonding Devices, above, if you're not sure about your | |
1014 | network initialization scripts. | |
1015 | ||
1016 | To load multiple instances of the module, it is necessary to | |
1017 | specify a different name for each instance (the module loading system | |
1018 | requires that every loaded module, even multiple instances of the same | |
1019 | module, have a unique name). This is accomplished by supplying multiple | |
1020 | sets of bonding options in /etc/modprobe.conf, for example: | |
1021 | ||
1022 | alias bond0 bonding | |
1023 | options bond0 -o bond0 mode=balance-rr miimon=100 | |
1024 | ||
1025 | alias bond1 bonding | |
1026 | options bond1 -o bond1 mode=balance-alb miimon=50 | |
1027 | ||
1028 | will load the bonding module two times. The first instance is | |
1029 | named "bond0" and creates the bond0 device in balance-rr mode with an | |
1030 | miimon of 100. The second instance is named "bond1" and creates the | |
1031 | bond1 device in balance-alb mode with an miimon of 50. | |
1032 | ||
1033 | In some circumstances (typically with older distributions), | |
1034 | the above does not work, and the second bonding instance never sees | |
1035 | its options. In that case, the second options line can be substituted | |
1036 | as follows: | |
1037 | ||
1038 | install bond1 /sbin/modprobe --ignore-install bonding -o bond1 \ | |
1039 | mode=balance-alb miimon=50 | |
00354cfb | 1040 | |
9a6c6867 JV |
1041 | This may be repeated any number of times, specifying a new and |
1042 | unique name in place of bond1 for each subsequent instance. | |
1043 | ||
1044 | It has been observed that some Red Hat supplied kernels are unable | |
1045 | to rename modules at load time (the "-o bond1" part). Attempts to pass | |
1046 | that option to modprobe will produce an "Operation not permitted" error. | |
1047 | This has been reported on some Fedora Core kernels, and has been seen on | |
1048 | RHEL 4 as well. On kernels exhibiting this problem, it will be impossible | |
1049 | to configure multiple bonds with differing parameters (as they are older | |
1050 | kernels, and also lack sysfs support). | |
1da177e4 | 1051 | |
6224e01d AK |
1052 | 3.4 Configuring Bonding Manually via Sysfs |
1053 | ------------------------------------------ | |
1054 | ||
9a6c6867 | 1055 | Starting with version 3.0.0, Channel Bonding may be configured |
6224e01d AK |
1056 | via the sysfs interface. This interface allows dynamic configuration |
1057 | of all bonds in the system without unloading the module. It also | |
1058 | allows for adding and removing bonds at runtime. Ifenslave is no | |
1059 | longer required, though it is still supported. | |
1060 | ||
1061 | Use of the sysfs interface allows you to use multiple bonds | |
1062 | with different configurations without having to reload the module. | |
1063 | It also allows you to use multiple, differently configured bonds when | |
1064 | bonding is compiled into the kernel. | |
1065 | ||
1066 | You must have the sysfs filesystem mounted to configure | |
1067 | bonding this way. The examples in this document assume that you | |
1068 | are using the standard mount point for sysfs, e.g. /sys. If your | |
1069 | sysfs filesystem is mounted elsewhere, you will need to adjust the | |
1070 | example paths accordingly. | |
1071 | ||
1072 | Creating and Destroying Bonds | |
1073 | ----------------------------- | |
1074 | To add a new bond foo: | |
1075 | # echo +foo > /sys/class/net/bonding_masters | |
1076 | ||
1077 | To remove an existing bond bar: | |
1078 | # echo -bar > /sys/class/net/bonding_masters | |
1079 | ||
1080 | To show all existing bonds: | |
1081 | # cat /sys/class/net/bonding_masters | |
1082 | ||
1083 | NOTE: due to 4K size limitation of sysfs files, this list may be | |
1084 | truncated if you have more than a few hundred bonds. This is unlikely | |
1085 | to occur under normal operating conditions. | |
1086 | ||
1087 | Adding and Removing Slaves | |
1088 | -------------------------- | |
1089 | Interfaces may be enslaved to a bond using the file | |
1090 | /sys/class/net/<bond>/bonding/slaves. The semantics for this file | |
1091 | are the same as for the bonding_masters file. | |
1092 | ||
1093 | To enslave interface eth0 to bond bond0: | |
1094 | # ifconfig bond0 up | |
1095 | # echo +eth0 > /sys/class/net/bond0/bonding/slaves | |
1096 | ||
1097 | To free slave eth0 from bond bond0: | |
1098 | # echo -eth0 > /sys/class/net/bond0/bonding/slaves | |
1099 | ||
6224e01d AK |
1100 | When an interface is enslaved to a bond, symlinks between the |
1101 | two are created in the sysfs filesystem. In this case, you would get | |
1102 | /sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and | |
1103 | /sys/class/net/eth0/master pointing to /sys/class/net/bond0. | |
1104 | ||
1105 | This means that you can tell quickly whether or not an | |
1106 | interface is enslaved by looking for the master symlink. Thus: | |
1107 | # echo -eth0 > /sys/class/net/eth0/master/bonding/slaves | |
1108 | will free eth0 from whatever bond it is enslaved to, regardless of | |
1109 | the name of the bond interface. | |
1110 | ||
1111 | Changing a Bond's Configuration | |
1112 | ------------------------------- | |
1113 | Each bond may be configured individually by manipulating the | |
1114 | files located in /sys/class/net/<bond name>/bonding | |
1115 | ||
1116 | The names of these files correspond directly with the command- | |
670e9f34 | 1117 | line parameters described elsewhere in this file, and, with the |
6224e01d AK |
1118 | exception of arp_ip_target, they accept the same values. To see the |
1119 | current setting, simply cat the appropriate file. | |
1120 | ||
1121 | A few examples will be given here; for specific usage | |
1122 | guidelines for each parameter, see the appropriate section in this | |
1123 | document. | |
1124 | ||
1125 | To configure bond0 for balance-alb mode: | |
1126 | # ifconfig bond0 down | |
1127 | # echo 6 > /sys/class/net/bond0/bonding/mode | |
1128 | - or - | |
1129 | # echo balance-alb > /sys/class/net/bond0/bonding/mode | |
1130 | NOTE: The bond interface must be down before the mode can be | |
1131 | changed. | |
1132 | ||
1133 | To enable MII monitoring on bond0 with a 1 second interval: | |
1134 | # echo 1000 > /sys/class/net/bond0/bonding/miimon | |
1135 | NOTE: If ARP monitoring is enabled, it will disabled when MII | |
1136 | monitoring is enabled, and vice-versa. | |
1137 | ||
1138 | To add ARP targets: | |
1139 | # echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target | |
1140 | # echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target | |
1141 | NOTE: up to 10 target addresses may be specified. | |
1142 | ||
1143 | To remove an ARP target: | |
1144 | # echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target | |
1145 | ||
1146 | Example Configuration | |
1147 | --------------------- | |
1148 | We begin with the same example that is shown in section 3.3, | |
1149 | executed with sysfs, and without using ifenslave. | |
1150 | ||
1151 | To make a simple bond of two e100 devices (presumed to be eth0 | |
1152 | and eth1), and have it persist across reboots, edit the appropriate | |
1153 | file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the | |
1154 | following: | |
1155 | ||
1156 | modprobe bonding | |
1157 | modprobe e100 | |
1158 | echo balance-alb > /sys/class/net/bond0/bonding/mode | |
1159 | ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up | |
1160 | echo 100 > /sys/class/net/bond0/bonding/miimon | |
1161 | echo +eth0 > /sys/class/net/bond0/bonding/slaves | |
1162 | echo +eth1 > /sys/class/net/bond0/bonding/slaves | |
1163 | ||
1164 | To add a second bond, with two e1000 interfaces in | |
1165 | active-backup mode, using ARP monitoring, add the following lines to | |
1166 | your init script: | |
1167 | ||
1168 | modprobe e1000 | |
1169 | echo +bond1 > /sys/class/net/bonding_masters | |
1170 | echo active-backup > /sys/class/net/bond1/bonding/mode | |
1171 | ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up | |
1172 | echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target | |
1173 | echo 2000 > /sys/class/net/bond1/bonding/arp_interval | |
1174 | echo +eth2 > /sys/class/net/bond1/bonding/slaves | |
1175 | echo +eth3 > /sys/class/net/bond1/bonding/slaves | |
1176 | ||
1da177e4 | 1177 | |
6224e01d | 1178 | 4. Querying Bonding Configuration |
1da177e4 LT |
1179 | ================================= |
1180 | ||
6224e01d | 1181 | 4.1 Bonding Configuration |
1da177e4 LT |
1182 | ------------------------- |
1183 | ||
1184 | Each bonding device has a read-only file residing in the | |
1185 | /proc/net/bonding directory. The file contents include information | |
1186 | about the bonding configuration, options and state of each slave. | |
1187 | ||
1188 | For example, the contents of /proc/net/bonding/bond0 after the | |
1189 | driver is loaded with parameters of mode=0 and miimon=1000 is | |
1190 | generally as follows: | |
1191 | ||
1192 | Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004) | |
1193 | Bonding Mode: load balancing (round-robin) | |
1194 | Currently Active Slave: eth0 | |
1195 | MII Status: up | |
1196 | MII Polling Interval (ms): 1000 | |
1197 | Up Delay (ms): 0 | |
1198 | Down Delay (ms): 0 | |
1199 | ||
1200 | Slave Interface: eth1 | |
1201 | MII Status: up | |
1202 | Link Failure Count: 1 | |
1203 | ||
1204 | Slave Interface: eth0 | |
1205 | MII Status: up | |
1206 | Link Failure Count: 1 | |
1207 | ||
1208 | The precise format and contents will change depending upon the | |
1209 | bonding configuration, state, and version of the bonding driver. | |
1210 | ||
6224e01d | 1211 | 4.2 Network configuration |
1da177e4 LT |
1212 | ------------------------- |
1213 | ||
1214 | The network configuration can be inspected using the ifconfig | |
1215 | command. Bonding devices will have the MASTER flag set; Bonding slave | |
1216 | devices will have the SLAVE flag set. The ifconfig output does not | |
1217 | contain information on which slaves are associated with which masters. | |
1218 | ||
1219 | In the example below, the bond0 interface is the master | |
1220 | (MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of | |
1221 | bond0 have the same MAC address (HWaddr) as bond0 for all modes except | |
1222 | TLB and ALB that require a unique MAC address for each slave. | |
1223 | ||
1224 | # /sbin/ifconfig | |
1225 | bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1226 | inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0 | |
1227 | UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 | |
1228 | RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0 | |
1229 | TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0 | |
1230 | collisions:0 txqueuelen:0 | |
1231 | ||
1232 | eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1da177e4 LT |
1233 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
1234 | RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0 | |
1235 | TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0 | |
1236 | collisions:0 txqueuelen:100 | |
1237 | Interrupt:10 Base address:0x1080 | |
1238 | ||
1239 | eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1da177e4 LT |
1240 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
1241 | RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0 | |
1242 | TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0 | |
1243 | collisions:0 txqueuelen:100 | |
1244 | Interrupt:9 Base address:0x1400 | |
1245 | ||
6224e01d | 1246 | 5. Switch Configuration |
1da177e4 LT |
1247 | ======================= |
1248 | ||
1249 | For this section, "switch" refers to whatever system the | |
1250 | bonded devices are directly connected to (i.e., where the other end of | |
1251 | the cable plugs into). This may be an actual dedicated switch device, | |
1252 | or it may be another regular system (e.g., another computer running | |
1253 | Linux), | |
1254 | ||
1255 | The active-backup, balance-tlb and balance-alb modes do not | |
1256 | require any specific configuration of the switch. | |
1257 | ||
1258 | The 802.3ad mode requires that the switch have the appropriate | |
1259 | ports configured as an 802.3ad aggregation. The precise method used | |
1260 | to configure this varies from switch to switch, but, for example, a | |
1261 | Cisco 3550 series switch requires that the appropriate ports first be | |
1262 | grouped together in a single etherchannel instance, then that | |
1263 | etherchannel is set to mode "lacp" to enable 802.3ad (instead of | |
1264 | standard EtherChannel). | |
1265 | ||
1266 | The balance-rr, balance-xor and broadcast modes generally | |
1267 | require that the switch have the appropriate ports grouped together. | |
1268 | The nomenclature for such a group differs between switches, it may be | |
1269 | called an "etherchannel" (as in the Cisco example, above), a "trunk | |
1270 | group" or some other similar variation. For these modes, each switch | |
1271 | will also have its own configuration options for the switch's transmit | |
1272 | policy to the bond. Typical choices include XOR of either the MAC or | |
1273 | IP addresses. The transmit policy of the two peers does not need to | |
1274 | match. For these three modes, the bonding mode really selects a | |
1275 | transmit policy for an EtherChannel group; all three will interoperate | |
1276 | with another EtherChannel group. | |
1277 | ||
1278 | ||
6224e01d | 1279 | 6. 802.1q VLAN Support |
1da177e4 LT |
1280 | ====================== |
1281 | ||
1282 | It is possible to configure VLAN devices over a bond interface | |
1283 | using the 8021q driver. However, only packets coming from the 8021q | |
1284 | driver and passing through bonding will be tagged by default. Self | |
1285 | generated packets, for example, bonding's learning packets or ARP | |
1286 | packets generated by either ALB mode or the ARP monitor mechanism, are | |
1287 | tagged internally by bonding itself. As a result, bonding must | |
1288 | "learn" the VLAN IDs configured above it, and use those IDs to tag | |
1289 | self generated packets. | |
1290 | ||
1291 | For reasons of simplicity, and to support the use of adapters | |
00354cfb JV |
1292 | that can do VLAN hardware acceleration offloading, the bonding |
1293 | interface declares itself as fully hardware offloading capable, it gets | |
1da177e4 LT |
1294 | the add_vid/kill_vid notifications to gather the necessary |
1295 | information, and it propagates those actions to the slaves. In case | |
1296 | of mixed adapter types, hardware accelerated tagged packets that | |
1297 | should go through an adapter that is not offloading capable are | |
1298 | "un-accelerated" by the bonding driver so the VLAN tag sits in the | |
1299 | regular location. | |
1300 | ||
1301 | VLAN interfaces *must* be added on top of a bonding interface | |
1302 | only after enslaving at least one slave. The bonding interface has a | |
1303 | hardware address of 00:00:00:00:00:00 until the first slave is added. | |
1304 | If the VLAN interface is created prior to the first enslavement, it | |
1305 | would pick up the all-zeroes hardware address. Once the first slave | |
1306 | is attached to the bond, the bond device itself will pick up the | |
1307 | slave's hardware address, which is then available for the VLAN device. | |
1308 | ||
1309 | Also, be aware that a similar problem can occur if all slaves | |
1310 | are released from a bond that still has one or more VLAN interfaces on | |
1311 | top of it. When a new slave is added, the bonding interface will | |
1312 | obtain its hardware address from the first slave, which might not | |
1313 | match the hardware address of the VLAN interfaces (which was | |
1314 | ultimately copied from an earlier slave). | |
1315 | ||
1316 | There are two methods to insure that the VLAN device operates | |
1317 | with the correct hardware address if all slaves are removed from a | |
1318 | bond interface: | |
1319 | ||
1320 | 1. Remove all VLAN interfaces then recreate them | |
1321 | ||
1322 | 2. Set the bonding interface's hardware address so that it | |
1323 | matches the hardware address of the VLAN interfaces. | |
1324 | ||
1325 | Note that changing a VLAN interface's HW address would set the | |
00354cfb | 1326 | underlying device -- i.e. the bonding interface -- to promiscuous |
1da177e4 LT |
1327 | mode, which might not be what you want. |
1328 | ||
1329 | ||
6224e01d | 1330 | 7. Link Monitoring |
1da177e4 LT |
1331 | ================== |
1332 | ||
1333 | The bonding driver at present supports two schemes for | |
1334 | monitoring a slave device's link state: the ARP monitor and the MII | |
1335 | monitor. | |
1336 | ||
1337 | At the present time, due to implementation restrictions in the | |
1338 | bonding driver itself, it is not possible to enable both ARP and MII | |
1339 | monitoring simultaneously. | |
1340 | ||
6224e01d | 1341 | 7.1 ARP Monitor Operation |
1da177e4 LT |
1342 | ------------------------- |
1343 | ||
1344 | The ARP monitor operates as its name suggests: it sends ARP | |
1345 | queries to one or more designated peer systems on the network, and | |
1346 | uses the response as an indication that the link is operating. This | |
1347 | gives some assurance that traffic is actually flowing to and from one | |
1348 | or more peers on the local network. | |
1349 | ||
1350 | The ARP monitor relies on the device driver itself to verify | |
1351 | that traffic is flowing. In particular, the driver must keep up to | |
1352 | date the last receive time, dev->last_rx, and transmit start time, | |
1353 | dev->trans_start. If these are not updated by the driver, then the | |
1354 | ARP monitor will immediately fail any slaves using that driver, and | |
1355 | those slaves will stay down. If networking monitoring (tcpdump, etc) | |
1356 | shows the ARP requests and replies on the network, then it may be that | |
1357 | your device driver is not updating last_rx and trans_start. | |
1358 | ||
6224e01d | 1359 | 7.2 Configuring Multiple ARP Targets |
1da177e4 LT |
1360 | ------------------------------------ |
1361 | ||
1362 | While ARP monitoring can be done with just one target, it can | |
1363 | be useful in a High Availability setup to have several targets to | |
1364 | monitor. In the case of just one target, the target itself may go | |
1365 | down or have a problem making it unresponsive to ARP requests. Having | |
1366 | an additional target (or several) increases the reliability of the ARP | |
1367 | monitoring. | |
1368 | ||
00354cfb | 1369 | Multiple ARP targets must be separated by commas as follows: |
1da177e4 LT |
1370 | |
1371 | # example options for ARP monitoring with three targets | |
1372 | alias bond0 bonding | |
1373 | options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9 | |
1374 | ||
1375 | For just a single target the options would resemble: | |
1376 | ||
1377 | # example options for ARP monitoring with one target | |
1378 | alias bond0 bonding | |
1379 | options bond0 arp_interval=60 arp_ip_target=192.168.0.100 | |
1380 | ||
1381 | ||
6224e01d | 1382 | 7.3 MII Monitor Operation |
1da177e4 LT |
1383 | ------------------------- |
1384 | ||
1385 | The MII monitor monitors only the carrier state of the local | |
1386 | network interface. It accomplishes this in one of three ways: by | |
1387 | depending upon the device driver to maintain its carrier state, by | |
1388 | querying the device's MII registers, or by making an ethtool query to | |
1389 | the device. | |
1390 | ||
1391 | If the use_carrier module parameter is 1 (the default value), | |
1392 | then the MII monitor will rely on the driver for carrier state | |
1393 | information (via the netif_carrier subsystem). As explained in the | |
1394 | use_carrier parameter information, above, if the MII monitor fails to | |
1395 | detect carrier loss on the device (e.g., when the cable is physically | |
1396 | disconnected), it may be that the driver does not support | |
1397 | netif_carrier. | |
1398 | ||
1399 | If use_carrier is 0, then the MII monitor will first query the | |
1400 | device's (via ioctl) MII registers and check the link state. If that | |
1401 | request fails (not just that it returns carrier down), then the MII | |
1402 | monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain | |
1403 | the same information. If both methods fail (i.e., the driver either | |
1404 | does not support or had some error in processing both the MII register | |
1405 | and ethtool requests), then the MII monitor will assume the link is | |
1406 | up. | |
1407 | ||
6224e01d | 1408 | 8. Potential Sources of Trouble |
1da177e4 LT |
1409 | =============================== |
1410 | ||
6224e01d | 1411 | 8.1 Adventures in Routing |
1da177e4 LT |
1412 | ------------------------- |
1413 | ||
1414 | When bonding is configured, it is important that the slave | |
6224e01d | 1415 | devices not have routes that supersede routes of the master (or, |
1da177e4 LT |
1416 | generally, not have routes at all). For example, suppose the bonding |
1417 | device bond0 has two slaves, eth0 and eth1, and the routing table is | |
1418 | as follows: | |
1419 | ||
1420 | Kernel IP routing table | |
1421 | Destination Gateway Genmask Flags MSS Window irtt Iface | |
1422 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth0 | |
1423 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth1 | |
1424 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 bond0 | |
1425 | 127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo | |
1426 | ||
1427 | This routing configuration will likely still update the | |
1428 | receive/transmit times in the driver (needed by the ARP monitor), but | |
1429 | may bypass the bonding driver (because outgoing traffic to, in this | |
1430 | case, another host on network 10 would use eth0 or eth1 before bond0). | |
1431 | ||
1432 | The ARP monitor (and ARP itself) may become confused by this | |
1433 | configuration, because ARP requests (generated by the ARP monitor) | |
1434 | will be sent on one interface (bond0), but the corresponding reply | |
1435 | will arrive on a different interface (eth0). This reply looks to ARP | |
1436 | as an unsolicited ARP reply (because ARP matches replies on an | |
1437 | interface basis), and is discarded. The MII monitor is not affected | |
1438 | by the state of the routing table. | |
1439 | ||
1440 | The solution here is simply to insure that slaves do not have | |
1441 | routes of their own, and if for some reason they must, those routes do | |
6224e01d | 1442 | not supersede routes of their master. This should generally be the |
1da177e4 LT |
1443 | case, but unusual configurations or errant manual or automatic static |
1444 | route additions may cause trouble. | |
1445 | ||
6224e01d | 1446 | 8.2 Ethernet Device Renaming |
1da177e4 LT |
1447 | ---------------------------- |
1448 | ||
1449 | On systems with network configuration scripts that do not | |
1450 | associate physical devices directly with network interface names (so | |
1451 | that the same physical device always has the same "ethX" name), it may | |
1452 | be necessary to add some special logic to either /etc/modules.conf or | |
1453 | /etc/modprobe.conf (depending upon which is installed on the system). | |
1454 | ||
1455 | For example, given a modules.conf containing the following: | |
1456 | ||
1457 | alias bond0 bonding | |
1458 | options bond0 mode=some-mode miimon=50 | |
1459 | alias eth0 tg3 | |
1460 | alias eth1 tg3 | |
1461 | alias eth2 e1000 | |
1462 | alias eth3 e1000 | |
1463 | ||
1464 | If neither eth0 and eth1 are slaves to bond0, then when the | |
1465 | bond0 interface comes up, the devices may end up reordered. This | |
1466 | happens because bonding is loaded first, then its slave device's | |
1467 | drivers are loaded next. Since no other drivers have been loaded, | |
1468 | when the e1000 driver loads, it will receive eth0 and eth1 for its | |
1469 | devices, but the bonding configuration tries to enslave eth2 and eth3 | |
1470 | (which may later be assigned to the tg3 devices). | |
1471 | ||
1472 | Adding the following: | |
1473 | ||
1474 | add above bonding e1000 tg3 | |
1475 | ||
1476 | causes modprobe to load e1000 then tg3, in that order, when | |
1477 | bonding is loaded. This command is fully documented in the | |
1478 | modules.conf manual page. | |
1479 | ||
1480 | On systems utilizing modprobe.conf (or modprobe.conf.local), | |
1481 | an equivalent problem can occur. In this case, the following can be | |
1482 | added to modprobe.conf (or modprobe.conf.local, as appropriate), as | |
1483 | follows (all on one line; it has been split here for clarity): | |
1484 | ||
1485 | install bonding /sbin/modprobe tg3; /sbin/modprobe e1000; | |
1486 | /sbin/modprobe --ignore-install bonding | |
1487 | ||
1488 | This will, when loading the bonding module, rather than | |
1489 | performing the normal action, instead execute the provided command. | |
1490 | This command loads the device drivers in the order needed, then calls | |
00354cfb | 1491 | modprobe with --ignore-install to cause the normal action to then take |
1da177e4 LT |
1492 | place. Full documentation on this can be found in the modprobe.conf |
1493 | and modprobe manual pages. | |
1494 | ||
6224e01d | 1495 | 8.3. Painfully Slow Or No Failed Link Detection By Miimon |
1da177e4 LT |
1496 | --------------------------------------------------------- |
1497 | ||
1498 | By default, bonding enables the use_carrier option, which | |
1499 | instructs bonding to trust the driver to maintain carrier state. | |
1500 | ||
1501 | As discussed in the options section, above, some drivers do | |
1502 | not support the netif_carrier_on/_off link state tracking system. | |
1503 | With use_carrier enabled, bonding will always see these links as up, | |
1504 | regardless of their actual state. | |
1505 | ||
1506 | Additionally, other drivers do support netif_carrier, but do | |
1507 | not maintain it in real time, e.g., only polling the link state at | |
1508 | some fixed interval. In this case, miimon will detect failures, but | |
1509 | only after some long period of time has expired. If it appears that | |
1510 | miimon is very slow in detecting link failures, try specifying | |
1511 | use_carrier=0 to see if that improves the failure detection time. If | |
1512 | it does, then it may be that the driver checks the carrier state at a | |
1513 | fixed interval, but does not cache the MII register values (so the | |
1514 | use_carrier=0 method of querying the registers directly works). If | |
1515 | use_carrier=0 does not improve the failover, then the driver may cache | |
1516 | the registers, or the problem may be elsewhere. | |
1517 | ||
1518 | Also, remember that miimon only checks for the device's | |
1519 | carrier state. It has no way to determine the state of devices on or | |
1520 | beyond other ports of a switch, or if a switch is refusing to pass | |
1521 | traffic while still maintaining carrier on. | |
1522 | ||
6224e01d | 1523 | 9. SNMP agents |
1da177e4 LT |
1524 | =============== |
1525 | ||
1526 | If running SNMP agents, the bonding driver should be loaded | |
1527 | before any network drivers participating in a bond. This requirement | |
d533f671 | 1528 | is due to the interface index (ipAdEntIfIndex) being associated to |
1da177e4 LT |
1529 | the first interface found with a given IP address. That is, there is |
1530 | only one ipAdEntIfIndex for each IP address. For example, if eth0 and | |
1531 | eth1 are slaves of bond0 and the driver for eth0 is loaded before the | |
1532 | bonding driver, the interface for the IP address will be associated | |
1533 | with the eth0 interface. This configuration is shown below, the IP | |
1534 | address 192.168.1.1 has an interface index of 2 which indexes to eth0 | |
1535 | in the ifDescr table (ifDescr.2). | |
1536 | ||
1537 | interfaces.ifTable.ifEntry.ifDescr.1 = lo | |
1538 | interfaces.ifTable.ifEntry.ifDescr.2 = eth0 | |
1539 | interfaces.ifTable.ifEntry.ifDescr.3 = eth1 | |
1540 | interfaces.ifTable.ifEntry.ifDescr.4 = eth2 | |
1541 | interfaces.ifTable.ifEntry.ifDescr.5 = eth3 | |
1542 | interfaces.ifTable.ifEntry.ifDescr.6 = bond0 | |
1543 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5 | |
1544 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 | |
1545 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4 | |
1546 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 | |
1547 | ||
1548 | This problem is avoided by loading the bonding driver before | |
1549 | any network drivers participating in a bond. Below is an example of | |
1550 | loading the bonding driver first, the IP address 192.168.1.1 is | |
1551 | correctly associated with ifDescr.2. | |
1552 | ||
1553 | interfaces.ifTable.ifEntry.ifDescr.1 = lo | |
1554 | interfaces.ifTable.ifEntry.ifDescr.2 = bond0 | |
1555 | interfaces.ifTable.ifEntry.ifDescr.3 = eth0 | |
1556 | interfaces.ifTable.ifEntry.ifDescr.4 = eth1 | |
1557 | interfaces.ifTable.ifEntry.ifDescr.5 = eth2 | |
1558 | interfaces.ifTable.ifEntry.ifDescr.6 = eth3 | |
1559 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6 | |
1560 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 | |
1561 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5 | |
1562 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 | |
1563 | ||
1564 | While some distributions may not report the interface name in | |
1565 | ifDescr, the association between the IP address and IfIndex remains | |
1566 | and SNMP functions such as Interface_Scan_Next will report that | |
1567 | association. | |
1568 | ||
6224e01d | 1569 | 10. Promiscuous mode |
1da177e4 LT |
1570 | ==================== |
1571 | ||
1572 | When running network monitoring tools, e.g., tcpdump, it is | |
1573 | common to enable promiscuous mode on the device, so that all traffic | |
1574 | is seen (instead of seeing only traffic destined for the local host). | |
1575 | The bonding driver handles promiscuous mode changes to the bonding | |
00354cfb | 1576 | master device (e.g., bond0), and propagates the setting to the slave |
1da177e4 LT |
1577 | devices. |
1578 | ||
1579 | For the balance-rr, balance-xor, broadcast, and 802.3ad modes, | |
00354cfb | 1580 | the promiscuous mode setting is propagated to all slaves. |
1da177e4 LT |
1581 | |
1582 | For the active-backup, balance-tlb and balance-alb modes, the | |
00354cfb | 1583 | promiscuous mode setting is propagated only to the active slave. |
1da177e4 LT |
1584 | |
1585 | For balance-tlb mode, the active slave is the slave currently | |
1586 | receiving inbound traffic. | |
1587 | ||
1588 | For balance-alb mode, the active slave is the slave used as a | |
1589 | "primary." This slave is used for mode-specific control traffic, for | |
1590 | sending to peers that are unassigned or if the load is unbalanced. | |
1591 | ||
1592 | For the active-backup, balance-tlb and balance-alb modes, when | |
1593 | the active slave changes (e.g., due to a link failure), the | |
00354cfb | 1594 | promiscuous setting will be propagated to the new active slave. |
1da177e4 | 1595 | |
6224e01d | 1596 | 11. Configuring Bonding for High Availability |
00354cfb | 1597 | ============================================= |
1da177e4 LT |
1598 | |
1599 | High Availability refers to configurations that provide | |
1600 | maximum network availability by having redundant or backup devices, | |
00354cfb JV |
1601 | links or switches between the host and the rest of the world. The |
1602 | goal is to provide the maximum availability of network connectivity | |
1603 | (i.e., the network always works), even though other configurations | |
1604 | could provide higher throughput. | |
1da177e4 | 1605 | |
6224e01d | 1606 | 11.1 High Availability in a Single Switch Topology |
1da177e4 LT |
1607 | -------------------------------------------------- |
1608 | ||
00354cfb JV |
1609 | If two hosts (or a host and a single switch) are directly |
1610 | connected via multiple physical links, then there is no availability | |
1611 | penalty to optimizing for maximum bandwidth. In this case, there is | |
1612 | only one switch (or peer), so if it fails, there is no alternative | |
1613 | access to fail over to. Additionally, the bonding load balance modes | |
1614 | support link monitoring of their members, so if individual links fail, | |
1615 | the load will be rebalanced across the remaining devices. | |
1616 | ||
1617 | See Section 13, "Configuring Bonding for Maximum Throughput" | |
1618 | for information on configuring bonding with one peer device. | |
1619 | ||
6224e01d | 1620 | 11.2 High Availability in a Multiple Switch Topology |
00354cfb JV |
1621 | ---------------------------------------------------- |
1622 | ||
1623 | With multiple switches, the configuration of bonding and the | |
1624 | network changes dramatically. In multiple switch topologies, there is | |
1625 | a trade off between network availability and usable bandwidth. | |
1626 | ||
1627 | Below is a sample network, configured to maximize the | |
1628 | availability of the network: | |
1da177e4 | 1629 | |
00354cfb JV |
1630 | | | |
1631 | |port3 port3| | |
1632 | +-----+----+ +-----+----+ | |
1633 | | |port2 ISL port2| | | |
1634 | | switch A +--------------------------+ switch B | | |
1635 | | | | | | |
1636 | +-----+----+ +-----++---+ | |
1637 | |port1 port1| | |
1638 | | +-------+ | | |
1639 | +-------------+ host1 +---------------+ | |
1640 | eth0 +-------+ eth1 | |
1da177e4 | 1641 | |
00354cfb JV |
1642 | In this configuration, there is a link between the two |
1643 | switches (ISL, or inter switch link), and multiple ports connecting to | |
1644 | the outside world ("port3" on each switch). There is no technical | |
1645 | reason that this could not be extended to a third switch. | |
1da177e4 | 1646 | |
6224e01d | 1647 | 11.2.1 HA Bonding Mode Selection for Multiple Switch Topology |
00354cfb | 1648 | ------------------------------------------------------------- |
1da177e4 | 1649 | |
00354cfb JV |
1650 | In a topology such as the example above, the active-backup and |
1651 | broadcast modes are the only useful bonding modes when optimizing for | |
1652 | availability; the other modes require all links to terminate on the | |
1653 | same peer for them to behave rationally. | |
1654 | ||
1655 | active-backup: This is generally the preferred mode, particularly if | |
1656 | the switches have an ISL and play together well. If the | |
1657 | network configuration is such that one switch is specifically | |
1658 | a backup switch (e.g., has lower capacity, higher cost, etc), | |
1659 | then the primary option can be used to insure that the | |
1660 | preferred link is always used when it is available. | |
1661 | ||
1662 | broadcast: This mode is really a special purpose mode, and is suitable | |
1663 | only for very specific needs. For example, if the two | |
1664 | switches are not connected (no ISL), and the networks beyond | |
1665 | them are totally independent. In this case, if it is | |
1666 | necessary for some specific one-way traffic to reach both | |
1667 | independent networks, then the broadcast mode may be suitable. | |
1668 | ||
6224e01d | 1669 | 11.2.2 HA Link Monitoring Selection for Multiple Switch Topology |
00354cfb JV |
1670 | ---------------------------------------------------------------- |
1671 | ||
1672 | The choice of link monitoring ultimately depends upon your | |
1673 | switch. If the switch can reliably fail ports in response to other | |
1674 | failures, then either the MII or ARP monitors should work. For | |
1675 | example, in the above example, if the "port3" link fails at the remote | |
1676 | end, the MII monitor has no direct means to detect this. The ARP | |
1677 | monitor could be configured with a target at the remote end of port3, | |
1678 | thus detecting that failure without switch support. | |
1679 | ||
1680 | In general, however, in a multiple switch topology, the ARP | |
1681 | monitor can provide a higher level of reliability in detecting end to | |
1682 | end connectivity failures (which may be caused by the failure of any | |
1683 | individual component to pass traffic for any reason). Additionally, | |
1684 | the ARP monitor should be configured with multiple targets (at least | |
1685 | one for each switch in the network). This will insure that, | |
1686 | regardless of which switch is active, the ARP monitor has a suitable | |
1687 | target to query. | |
1688 | ||
9a6c6867 JV |
1689 | Note, also, that of late many switches now support a functionality |
1690 | generally referred to as "trunk failover." This is a feature of the | |
1691 | switch that causes the link state of a particular switch port to be set | |
1692 | down (or up) when the state of another switch port goes down (or up). | |
1693 | It's purpose is to propogate link failures from logically "exterior" ports | |
1694 | to the logically "interior" ports that bonding is able to monitor via | |
1695 | miimon. Availability and configuration for trunk failover varies by | |
1696 | switch, but this can be a viable alternative to the ARP monitor when using | |
1697 | suitable switches. | |
00354cfb | 1698 | |
6224e01d | 1699 | 12. Configuring Bonding for Maximum Throughput |
00354cfb JV |
1700 | ============================================== |
1701 | ||
6224e01d | 1702 | 12.1 Maximizing Throughput in a Single Switch Topology |
00354cfb JV |
1703 | ------------------------------------------------------ |
1704 | ||
1705 | In a single switch configuration, the best method to maximize | |
1706 | throughput depends upon the application and network environment. The | |
1707 | various load balancing modes each have strengths and weaknesses in | |
1708 | different environments, as detailed below. | |
1709 | ||
1710 | For this discussion, we will break down the topologies into | |
1711 | two categories. Depending upon the destination of most traffic, we | |
1712 | categorize them into either "gatewayed" or "local" configurations. | |
1713 | ||
1714 | In a gatewayed configuration, the "switch" is acting primarily | |
1715 | as a router, and the majority of traffic passes through this router to | |
1716 | other networks. An example would be the following: | |
1717 | ||
1718 | ||
1719 | +----------+ +----------+ | |
1720 | | |eth0 port1| | to other networks | |
1721 | | Host A +---------------------+ router +-------------------> | |
1722 | | +---------------------+ | Hosts B and C are out | |
1723 | | |eth1 port2| | here somewhere | |
1724 | +----------+ +----------+ | |
1725 | ||
1726 | The router may be a dedicated router device, or another host | |
1727 | acting as a gateway. For our discussion, the important point is that | |
1728 | the majority of traffic from Host A will pass through the router to | |
1729 | some other network before reaching its final destination. | |
1730 | ||
1731 | In a gatewayed network configuration, although Host A may | |
1732 | communicate with many other systems, all of its traffic will be sent | |
1733 | and received via one other peer on the local network, the router. | |
1734 | ||
1735 | Note that the case of two systems connected directly via | |
1736 | multiple physical links is, for purposes of configuring bonding, the | |
1737 | same as a gatewayed configuration. In that case, it happens that all | |
1738 | traffic is destined for the "gateway" itself, not some other network | |
1739 | beyond the gateway. | |
1740 | ||
1741 | In a local configuration, the "switch" is acting primarily as | |
1742 | a switch, and the majority of traffic passes through this switch to | |
1743 | reach other stations on the same network. An example would be the | |
1744 | following: | |
1745 | ||
1746 | +----------+ +----------+ +--------+ | |
1747 | | |eth0 port1| +-------+ Host B | | |
1748 | | Host A +------------+ switch |port3 +--------+ | |
1749 | | +------------+ | +--------+ | |
1750 | | |eth1 port2| +------------------+ Host C | | |
1751 | +----------+ +----------+port4 +--------+ | |
1752 | ||
1753 | ||
1754 | Again, the switch may be a dedicated switch device, or another | |
1755 | host acting as a gateway. For our discussion, the important point is | |
1756 | that the majority of traffic from Host A is destined for other hosts | |
1757 | on the same local network (Hosts B and C in the above example). | |
1758 | ||
1759 | In summary, in a gatewayed configuration, traffic to and from | |
1760 | the bonded device will be to the same MAC level peer on the network | |
1761 | (the gateway itself, i.e., the router), regardless of its final | |
1762 | destination. In a local configuration, traffic flows directly to and | |
1763 | from the final destinations, thus, each destination (Host B, Host C) | |
1764 | will be addressed directly by their individual MAC addresses. | |
1765 | ||
1766 | This distinction between a gatewayed and a local network | |
1767 | configuration is important because many of the load balancing modes | |
1768 | available use the MAC addresses of the local network source and | |
1769 | destination to make load balancing decisions. The behavior of each | |
1770 | mode is described below. | |
1771 | ||
1772 | ||
6224e01d | 1773 | 12.1.1 MT Bonding Mode Selection for Single Switch Topology |
00354cfb | 1774 | ----------------------------------------------------------- |
1da177e4 LT |
1775 | |
1776 | This configuration is the easiest to set up and to understand, | |
1777 | although you will have to decide which bonding mode best suits your | |
00354cfb | 1778 | needs. The trade offs for each mode are detailed below: |
1da177e4 LT |
1779 | |
1780 | balance-rr: This mode is the only mode that will permit a single | |
1781 | TCP/IP connection to stripe traffic across multiple | |
1782 | interfaces. It is therefore the only mode that will allow a | |
1783 | single TCP/IP stream to utilize more than one interface's | |
1784 | worth of throughput. This comes at a cost, however: the | |
9a6c6867 | 1785 | striping generally results in peer systems receiving packets out |
1da177e4 LT |
1786 | of order, causing TCP/IP's congestion control system to kick |
1787 | in, often by retransmitting segments. | |
1788 | ||
1789 | It is possible to adjust TCP/IP's congestion limits by | |
1790 | altering the net.ipv4.tcp_reordering sysctl parameter. The | |
1791 | usual default value is 3, and the maximum useful value is 127. | |
1792 | For a four interface balance-rr bond, expect that a single | |
1793 | TCP/IP stream will utilize no more than approximately 2.3 | |
1794 | interface's worth of throughput, even after adjusting | |
1795 | tcp_reordering. | |
1796 | ||
9a6c6867 JV |
1797 | Note that the fraction of packets that will be delivered out of |
1798 | order is highly variable, and is unlikely to be zero. The level | |
1799 | of reordering depends upon a variety of factors, including the | |
1800 | networking interfaces, the switch, and the topology of the | |
1801 | configuration. Speaking in general terms, higher speed network | |
1802 | cards produce more reordering (due to factors such as packet | |
1803 | coalescing), and a "many to many" topology will reorder at a | |
1804 | higher rate than a "many slow to one fast" configuration. | |
1805 | ||
1806 | Many switches do not support any modes that stripe traffic | |
1807 | (instead choosing a port based upon IP or MAC level addresses); | |
1808 | for those devices, traffic for a particular connection flowing | |
1809 | through the switch to a balance-rr bond will not utilize greater | |
1810 | than one interface's worth of bandwidth. | |
00354cfb | 1811 | |
1da177e4 LT |
1812 | If you are utilizing protocols other than TCP/IP, UDP for |
1813 | example, and your application can tolerate out of order | |
1814 | delivery, then this mode can allow for single stream datagram | |
1815 | performance that scales near linearly as interfaces are added | |
1816 | to the bond. | |
1817 | ||
1818 | This mode requires the switch to have the appropriate ports | |
1819 | configured for "etherchannel" or "trunking." | |
1820 | ||
1821 | active-backup: There is not much advantage in this network topology to | |
1822 | the active-backup mode, as the inactive backup devices are all | |
1823 | connected to the same peer as the primary. In this case, a | |
1824 | load balancing mode (with link monitoring) will provide the | |
1825 | same level of network availability, but with increased | |
00354cfb JV |
1826 | available bandwidth. On the plus side, active-backup mode |
1827 | does not require any configuration of the switch, so it may | |
1828 | have value if the hardware available does not support any of | |
1829 | the load balance modes. | |
1da177e4 LT |
1830 | |
1831 | balance-xor: This mode will limit traffic such that packets destined | |
1832 | for specific peers will always be sent over the same | |
1833 | interface. Since the destination is determined by the MAC | |
00354cfb JV |
1834 | addresses involved, this mode works best in a "local" network |
1835 | configuration (as described above), with destinations all on | |
1836 | the same local network. This mode is likely to be suboptimal | |
1837 | if all your traffic is passed through a single router (i.e., a | |
1838 | "gatewayed" network configuration, as described above). | |
1839 | ||
1840 | As with balance-rr, the switch ports need to be configured for | |
1da177e4 LT |
1841 | "etherchannel" or "trunking." |
1842 | ||
1843 | broadcast: Like active-backup, there is not much advantage to this | |
1844 | mode in this type of network topology. | |
1845 | ||
1846 | 802.3ad: This mode can be a good choice for this type of network | |
1847 | topology. The 802.3ad mode is an IEEE standard, so all peers | |
1848 | that implement 802.3ad should interoperate well. The 802.3ad | |
1849 | protocol includes automatic configuration of the aggregates, | |
1850 | so minimal manual configuration of the switch is needed | |
1851 | (typically only to designate that some set of devices is | |
00354cfb JV |
1852 | available for 802.3ad). The 802.3ad standard also mandates |
1853 | that frames be delivered in order (within certain limits), so | |
1854 | in general single connections will not see misordering of | |
1da177e4 LT |
1855 | packets. The 802.3ad mode does have some drawbacks: the |
1856 | standard mandates that all devices in the aggregate operate at | |
1857 | the same speed and duplex. Also, as with all bonding load | |
1858 | balance modes other than balance-rr, no single connection will | |
1859 | be able to utilize more than a single interface's worth of | |
00354cfb JV |
1860 | bandwidth. |
1861 | ||
1862 | Additionally, the linux bonding 802.3ad implementation | |
1863 | distributes traffic by peer (using an XOR of MAC addresses), | |
1864 | so in a "gatewayed" configuration, all outgoing traffic will | |
1865 | generally use the same device. Incoming traffic may also end | |
1866 | up on a single device, but that is dependent upon the | |
1867 | balancing policy of the peer's 8023.ad implementation. In a | |
1868 | "local" configuration, traffic will be distributed across the | |
1869 | devices in the bond. | |
1870 | ||
1871 | Finally, the 802.3ad mode mandates the use of the MII monitor, | |
1872 | therefore, the ARP monitor is not available in this mode. | |
1873 | ||
1874 | balance-tlb: The balance-tlb mode balances outgoing traffic by peer. | |
1875 | Since the balancing is done according to MAC address, in a | |
1876 | "gatewayed" configuration (as described above), this mode will | |
1877 | send all traffic across a single device. However, in a | |
1878 | "local" network configuration, this mode balances multiple | |
1879 | local network peers across devices in a vaguely intelligent | |
1880 | manner (not a simple XOR as in balance-xor or 802.3ad mode), | |
1881 | so that mathematically unlucky MAC addresses (i.e., ones that | |
1882 | XOR to the same value) will not all "bunch up" on a single | |
1883 | interface. | |
1884 | ||
1885 | Unlike 802.3ad, interfaces may be of differing speeds, and no | |
1886 | special switch configuration is required. On the down side, | |
1887 | in this mode all incoming traffic arrives over a single | |
1888 | interface, this mode requires certain ethtool support in the | |
1889 | network device driver of the slave interfaces, and the ARP | |
1890 | monitor is not available. | |
1891 | ||
1892 | balance-alb: This mode is everything that balance-tlb is, and more. | |
1893 | It has all of the features (and restrictions) of balance-tlb, | |
1894 | and will also balance incoming traffic from local network | |
1895 | peers (as described in the Bonding Module Options section, | |
1896 | above). | |
1897 | ||
1898 | The only additional down side to this mode is that the network | |
1899 | device driver must support changing the hardware address while | |
1900 | the device is open. | |
1901 | ||
6224e01d | 1902 | 12.1.2 MT Link Monitoring for Single Switch Topology |
00354cfb | 1903 | ---------------------------------------------------- |
1da177e4 LT |
1904 | |
1905 | The choice of link monitoring may largely depend upon which | |
1906 | mode you choose to use. The more advanced load balancing modes do not | |
1907 | support the use of the ARP monitor, and are thus restricted to using | |
00354cfb JV |
1908 | the MII monitor (which does not provide as high a level of end to end |
1909 | assurance as the ARP monitor). | |
1910 | ||
6224e01d | 1911 | 12.2 Maximum Throughput in a Multiple Switch Topology |
00354cfb JV |
1912 | ----------------------------------------------------- |
1913 | ||
1914 | Multiple switches may be utilized to optimize for throughput | |
1915 | when they are configured in parallel as part of an isolated network | |
1916 | between two or more systems, for example: | |
1917 | ||
1918 | +-----------+ | |
1919 | | Host A | | |
1920 | +-+---+---+-+ | |
1921 | | | | | |
1922 | +--------+ | +---------+ | |
1923 | | | | | |
1924 | +------+---+ +-----+----+ +-----+----+ | |
1925 | | Switch A | | Switch B | | Switch C | | |
1926 | +------+---+ +-----+----+ +-----+----+ | |
1927 | | | | | |
1928 | +--------+ | +---------+ | |
1929 | | | | | |
1930 | +-+---+---+-+ | |
1931 | | Host B | | |
1932 | +-----------+ | |
1933 | ||
1934 | In this configuration, the switches are isolated from one | |
1935 | another. One reason to employ a topology such as this is for an | |
1936 | isolated network with many hosts (a cluster configured for high | |
1937 | performance, for example), using multiple smaller switches can be more | |
1938 | cost effective than a single larger switch, e.g., on a network with 24 | |
1939 | hosts, three 24 port switches can be significantly less expensive than | |
1940 | a single 72 port switch. | |
1941 | ||
1942 | If access beyond the network is required, an individual host | |
1943 | can be equipped with an additional network device connected to an | |
1944 | external network; this host then additionally acts as a gateway. | |
1945 | ||
6224e01d | 1946 | 12.2.1 MT Bonding Mode Selection for Multiple Switch Topology |
1da177e4 LT |
1947 | ------------------------------------------------------------- |
1948 | ||
00354cfb JV |
1949 | In actual practice, the bonding mode typically employed in |
1950 | configurations of this type is balance-rr. Historically, in this | |
1951 | network configuration, the usual caveats about out of order packet | |
1952 | delivery are mitigated by the use of network adapters that do not do | |
1953 | any kind of packet coalescing (via the use of NAPI, or because the | |
1954 | device itself does not generate interrupts until some number of | |
1955 | packets has arrived). When employed in this fashion, the balance-rr | |
1956 | mode allows individual connections between two hosts to effectively | |
1957 | utilize greater than one interface's bandwidth. | |
1da177e4 | 1958 | |
6224e01d | 1959 | 12.2.2 MT Link Monitoring for Multiple Switch Topology |
00354cfb | 1960 | ------------------------------------------------------ |
1da177e4 | 1961 | |
00354cfb JV |
1962 | Again, in actual practice, the MII monitor is most often used |
1963 | in this configuration, as performance is given preference over | |
1964 | availability. The ARP monitor will function in this topology, but its | |
1965 | advantages over the MII monitor are mitigated by the volume of probes | |
1966 | needed as the number of systems involved grows (remember that each | |
1967 | host in the network is configured with bonding). | |
1da177e4 | 1968 | |
6224e01d | 1969 | 13. Switch Behavior Issues |
00354cfb | 1970 | ========================== |
1da177e4 | 1971 | |
6224e01d | 1972 | 13.1 Link Establishment and Failover Delays |
00354cfb JV |
1973 | ------------------------------------------- |
1974 | ||
1975 | Some switches exhibit undesirable behavior with regard to the | |
1976 | timing of link up and down reporting by the switch. | |
1da177e4 LT |
1977 | |
1978 | First, when a link comes up, some switches may indicate that | |
1979 | the link is up (carrier available), but not pass traffic over the | |
1980 | interface for some period of time. This delay is typically due to | |
1981 | some type of autonegotiation or routing protocol, but may also occur | |
1982 | during switch initialization (e.g., during recovery after a switch | |
1983 | failure). If you find this to be a problem, specify an appropriate | |
1984 | value to the updelay bonding module option to delay the use of the | |
1985 | relevant interface(s). | |
1986 | ||
1987 | Second, some switches may "bounce" the link state one or more | |
1988 | times while a link is changing state. This occurs most commonly while | |
1989 | the switch is initializing. Again, an appropriate updelay value may | |
00354cfb | 1990 | help. |
1da177e4 LT |
1991 | |
1992 | Note that when a bonding interface has no active links, the | |
00354cfb JV |
1993 | driver will immediately reuse the first link that goes up, even if the |
1994 | updelay parameter has been specified (the updelay is ignored in this | |
1995 | case). If there are slave interfaces waiting for the updelay timeout | |
1996 | to expire, the interface that first went into that state will be | |
1997 | immediately reused. This reduces down time of the network if the | |
1998 | value of updelay has been overestimated, and since this occurs only in | |
1999 | cases with no connectivity, there is no additional penalty for | |
2000 | ignoring the updelay. | |
1da177e4 LT |
2001 | |
2002 | In addition to the concerns about switch timings, if your | |
2003 | switches take a long time to go into backup mode, it may be desirable | |
2004 | to not activate a backup interface immediately after a link goes down. | |
2005 | Failover may be delayed via the downdelay bonding module option. | |
2006 | ||
6224e01d | 2007 | 13.2 Duplicated Incoming Packets |
00354cfb JV |
2008 | -------------------------------- |
2009 | ||
9a6c6867 JV |
2010 | NOTE: Starting with version 3.0.2, the bonding driver has logic to |
2011 | suppress duplicate packets, which should largely eliminate this problem. | |
2012 | The following description is kept for reference. | |
2013 | ||
00354cfb JV |
2014 | It is not uncommon to observe a short burst of duplicated |
2015 | traffic when the bonding device is first used, or after it has been | |
2016 | idle for some period of time. This is most easily observed by issuing | |
2017 | a "ping" to some other host on the network, and noticing that the | |
2018 | output from ping flags duplicates (typically one per slave). | |
2019 | ||
2020 | For example, on a bond in active-backup mode with five slaves | |
2021 | all connected to one switch, the output may appear as follows: | |
2022 | ||
2023 | # ping -n 10.0.4.2 | |
2024 | PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data. | |
2025 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms | |
2026 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2027 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2028 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2029 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2030 | 64 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms | |
2031 | 64 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms | |
2032 | 64 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms | |
2033 | ||
2034 | This is not due to an error in the bonding driver, rather, it | |
2035 | is a side effect of how many switches update their MAC forwarding | |
2036 | tables. Initially, the switch does not associate the MAC address in | |
2037 | the packet with a particular switch port, and so it may send the | |
2038 | traffic to all ports until its MAC forwarding table is updated. Since | |
2039 | the interfaces attached to the bond may occupy multiple ports on a | |
2040 | single switch, when the switch (temporarily) floods the traffic to all | |
2041 | ports, the bond device receives multiple copies of the same packet | |
2042 | (one per slave device). | |
2043 | ||
2044 | The duplicated packet behavior is switch dependent, some | |
2045 | switches exhibit this, and some do not. On switches that display this | |
2046 | behavior, it can be induced by clearing the MAC forwarding table (on | |
2047 | most Cisco switches, the privileged command "clear mac address-table | |
2048 | dynamic" will accomplish this). | |
2049 | ||
6224e01d | 2050 | 14. Hardware Specific Considerations |
1da177e4 LT |
2051 | ==================================== |
2052 | ||
2053 | This section contains additional information for configuring | |
2054 | bonding on specific hardware platforms, or for interfacing bonding | |
2055 | with particular switches or other devices. | |
2056 | ||
6224e01d | 2057 | 14.1 IBM BladeCenter |
1da177e4 LT |
2058 | -------------------- |
2059 | ||
2060 | This applies to the JS20 and similar systems. | |
2061 | ||
2062 | On the JS20 blades, the bonding driver supports only | |
2063 | balance-rr, active-backup, balance-tlb and balance-alb modes. This is | |
2064 | largely due to the network topology inside the BladeCenter, detailed | |
2065 | below. | |
2066 | ||
2067 | JS20 network adapter information | |
2068 | -------------------------------- | |
2069 | ||
2070 | All JS20s come with two Broadcom Gigabit Ethernet ports | |
00354cfb JV |
2071 | integrated on the planar (that's "motherboard" in IBM-speak). In the |
2072 | BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to | |
2073 | I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2. | |
2074 | An add-on Broadcom daughter card can be installed on a JS20 to provide | |
2075 | two more Gigabit Ethernet ports. These ports, eth2 and eth3, are | |
2076 | wired to I/O Modules 3 and 4, respectively. | |
1da177e4 LT |
2077 | |
2078 | Each I/O Module may contain either a switch or a passthrough | |
2079 | module (which allows ports to be directly connected to an external | |
2080 | switch). Some bonding modes require a specific BladeCenter internal | |
2081 | network topology in order to function; these are detailed below. | |
2082 | ||
2083 | Additional BladeCenter-specific networking information can be | |
2084 | found in two IBM Redbooks (www.ibm.com/redbooks): | |
2085 | ||
2086 | "IBM eServer BladeCenter Networking Options" | |
2087 | "IBM eServer BladeCenter Layer 2-7 Network Switching" | |
2088 | ||
2089 | BladeCenter networking configuration | |
2090 | ------------------------------------ | |
2091 | ||
2092 | Because a BladeCenter can be configured in a very large number | |
2093 | of ways, this discussion will be confined to describing basic | |
2094 | configurations. | |
2095 | ||
00354cfb | 2096 | Normally, Ethernet Switch Modules (ESMs) are used in I/O |
1da177e4 LT |
2097 | modules 1 and 2. In this configuration, the eth0 and eth1 ports of a |
2098 | JS20 will be connected to different internal switches (in the | |
2099 | respective I/O modules). | |
2100 | ||
00354cfb JV |
2101 | A passthrough module (OPM or CPM, optical or copper, |
2102 | passthrough module) connects the I/O module directly to an external | |
2103 | switch. By using PMs in I/O module #1 and #2, the eth0 and eth1 | |
2104 | interfaces of a JS20 can be redirected to the outside world and | |
2105 | connected to a common external switch. | |
2106 | ||
2107 | Depending upon the mix of ESMs and PMs, the network will | |
2108 | appear to bonding as either a single switch topology (all PMs) or as a | |
2109 | multiple switch topology (one or more ESMs, zero or more PMs). It is | |
2110 | also possible to connect ESMs together, resulting in a configuration | |
2111 | much like the example in "High Availability in a Multiple Switch | |
2112 | Topology," above. | |
2113 | ||
2114 | Requirements for specific modes | |
2115 | ------------------------------- | |
2116 | ||
2117 | The balance-rr mode requires the use of passthrough modules | |
2118 | for devices in the bond, all connected to an common external switch. | |
2119 | That switch must be configured for "etherchannel" or "trunking" on the | |
1da177e4 LT |
2120 | appropriate ports, as is usual for balance-rr. |
2121 | ||
2122 | The balance-alb and balance-tlb modes will function with | |
2123 | either switch modules or passthrough modules (or a mix). The only | |
2124 | specific requirement for these modes is that all network interfaces | |
2125 | must be able to reach all destinations for traffic sent over the | |
2126 | bonding device (i.e., the network must converge at some point outside | |
2127 | the BladeCenter). | |
2128 | ||
2129 | The active-backup mode has no additional requirements. | |
2130 | ||
2131 | Link monitoring issues | |
2132 | ---------------------- | |
2133 | ||
2134 | When an Ethernet Switch Module is in place, only the ARP | |
2135 | monitor will reliably detect link loss to an external switch. This is | |
2136 | nothing unusual, but examination of the BladeCenter cabinet would | |
2137 | suggest that the "external" network ports are the ethernet ports for | |
2138 | the system, when it fact there is a switch between these "external" | |
2139 | ports and the devices on the JS20 system itself. The MII monitor is | |
2140 | only able to detect link failures between the ESM and the JS20 system. | |
2141 | ||
2142 | When a passthrough module is in place, the MII monitor does | |
2143 | detect failures to the "external" port, which is then directly | |
2144 | connected to the JS20 system. | |
2145 | ||
2146 | Other concerns | |
2147 | -------------- | |
2148 | ||
00354cfb | 2149 | The Serial Over LAN (SoL) link is established over the primary |
1da177e4 LT |
2150 | ethernet (eth0) only, therefore, any loss of link to eth0 will result |
2151 | in losing your SoL connection. It will not fail over with other | |
00354cfb JV |
2152 | network traffic, as the SoL system is beyond the control of the |
2153 | bonding driver. | |
1da177e4 LT |
2154 | |
2155 | It may be desirable to disable spanning tree on the switch | |
2156 | (either the internal Ethernet Switch Module, or an external switch) to | |
00354cfb | 2157 | avoid fail-over delay issues when using bonding. |
1da177e4 LT |
2158 | |
2159 | ||
6224e01d | 2160 | 15. Frequently Asked Questions |
1da177e4 LT |
2161 | ============================== |
2162 | ||
2163 | 1. Is it SMP safe? | |
2164 | ||
2165 | Yes. The old 2.0.xx channel bonding patch was not SMP safe. | |
2166 | The new driver was designed to be SMP safe from the start. | |
2167 | ||
2168 | 2. What type of cards will work with it? | |
2169 | ||
2170 | Any Ethernet type cards (you can even mix cards - a Intel | |
00354cfb JV |
2171 | EtherExpress PRO/100 and a 3com 3c905b, for example). For most modes, |
2172 | devices need not be of the same speed. | |
1da177e4 | 2173 | |
9a6c6867 JV |
2174 | Starting with version 3.2.1, bonding also supports Infiniband |
2175 | slaves in active-backup mode. | |
2176 | ||
1da177e4 LT |
2177 | 3. How many bonding devices can I have? |
2178 | ||
2179 | There is no limit. | |
2180 | ||
2181 | 4. How many slaves can a bonding device have? | |
2182 | ||
2183 | This is limited only by the number of network interfaces Linux | |
2184 | supports and/or the number of network cards you can place in your | |
2185 | system. | |
2186 | ||
2187 | 5. What happens when a slave link dies? | |
2188 | ||
2189 | If link monitoring is enabled, then the failing device will be | |
2190 | disabled. The active-backup mode will fail over to a backup link, and | |
2191 | other modes will ignore the failed link. The link will continue to be | |
2192 | monitored, and should it recover, it will rejoin the bond (in whatever | |
00354cfb JV |
2193 | manner is appropriate for the mode). See the sections on High |
2194 | Availability and the documentation for each mode for additional | |
2195 | information. | |
1da177e4 LT |
2196 | |
2197 | Link monitoring can be enabled via either the miimon or | |
00354cfb | 2198 | arp_interval parameters (described in the module parameters section, |
1da177e4 LT |
2199 | above). In general, miimon monitors the carrier state as sensed by |
2200 | the underlying network device, and the arp monitor (arp_interval) | |
2201 | monitors connectivity to another host on the local network. | |
2202 | ||
2203 | If no link monitoring is configured, the bonding driver will | |
2204 | be unable to detect link failures, and will assume that all links are | |
2205 | always available. This will likely result in lost packets, and a | |
00354cfb | 2206 | resulting degradation of performance. The precise performance loss |
1da177e4 LT |
2207 | depends upon the bonding mode and network configuration. |
2208 | ||
2209 | 6. Can bonding be used for High Availability? | |
2210 | ||
2211 | Yes. See the section on High Availability for details. | |
2212 | ||
2213 | 7. Which switches/systems does it work with? | |
2214 | ||
2215 | The full answer to this depends upon the desired mode. | |
2216 | ||
2217 | In the basic balance modes (balance-rr and balance-xor), it | |
2218 | works with any system that supports etherchannel (also called | |
2219 | trunking). Most managed switches currently available have such | |
00354cfb | 2220 | support, and many unmanaged switches as well. |
1da177e4 LT |
2221 | |
2222 | The advanced balance modes (balance-tlb and balance-alb) do | |
2223 | not have special switch requirements, but do need device drivers that | |
2224 | support specific features (described in the appropriate section under | |
00354cfb | 2225 | module parameters, above). |
1da177e4 | 2226 | |
6224e01d | 2227 | In 802.3ad mode, it works with systems that support IEEE |
1da177e4 LT |
2228 | 802.3ad Dynamic Link Aggregation. Most managed and many unmanaged |
2229 | switches currently available support 802.3ad. | |
2230 | ||
2231 | The active-backup mode should work with any Layer-II switch. | |
2232 | ||
2233 | 8. Where does a bonding device get its MAC address from? | |
2234 | ||
9a6c6867 JV |
2235 | When using slave devices that have fixed MAC addresses, or when |
2236 | the fail_over_mac option is enabled, the bonding device's MAC address is | |
2237 | the MAC address of the active slave. | |
2238 | ||
2239 | For other configurations, if not explicitly configured (with | |
2240 | ifconfig or ip link), the MAC address of the bonding device is taken from | |
2241 | its first slave device. This MAC address is then passed to all following | |
2242 | slaves and remains persistent (even if the first slave is removed) until | |
2243 | the bonding device is brought down or reconfigured. | |
1da177e4 LT |
2244 | |
2245 | If you wish to change the MAC address, you can set it with | |
00354cfb | 2246 | ifconfig or ip link: |
1da177e4 LT |
2247 | |
2248 | # ifconfig bond0 hw ether 00:11:22:33:44:55 | |
2249 | ||
00354cfb JV |
2250 | # ip link set bond0 address 66:77:88:99:aa:bb |
2251 | ||
1da177e4 LT |
2252 | The MAC address can be also changed by bringing down/up the |
2253 | device and then changing its slaves (or their order): | |
2254 | ||
2255 | # ifconfig bond0 down ; modprobe -r bonding | |
2256 | # ifconfig bond0 .... up | |
2257 | # ifenslave bond0 eth... | |
2258 | ||
2259 | This method will automatically take the address from the next | |
2260 | slave that is added. | |
2261 | ||
2262 | To restore your slaves' MAC addresses, you need to detach them | |
2263 | from the bond (`ifenslave -d bond0 eth0'). The bonding driver will | |
2264 | then restore the MAC addresses that the slaves had before they were | |
2265 | enslaved. | |
2266 | ||
00354cfb | 2267 | 16. Resources and Links |
1da177e4 LT |
2268 | ======================= |
2269 | ||
2270 | The latest version of the bonding driver can be found in the latest | |
2271 | version of the linux kernel, found on http://kernel.org | |
2272 | ||
00354cfb JV |
2273 | The latest version of this document can be found in either the latest |
2274 | kernel source (named Documentation/networking/bonding.txt), or on the | |
2275 | bonding sourceforge site: | |
2276 | ||
2277 | http://www.sourceforge.net/projects/bonding | |
2278 | ||
1da177e4 LT |
2279 | Discussions regarding the bonding driver take place primarily on the |
2280 | bonding-devel mailing list, hosted at sourceforge.net. If you have | |
00354cfb | 2281 | questions or problems, post them to the list. The list address is: |
1da177e4 LT |
2282 | |
2283 | bonding-devel@lists.sourceforge.net | |
2284 | ||
00354cfb JV |
2285 | The administrative interface (to subscribe or unsubscribe) can |
2286 | be found at: | |
1da177e4 | 2287 | |
00354cfb | 2288 | https://lists.sourceforge.net/lists/listinfo/bonding-devel |
1da177e4 LT |
2289 | |
2290 | Donald Becker's Ethernet Drivers and diag programs may be found at : | |
2291 | - http://www.scyld.com/network/ | |
2292 | ||
2293 | You will also find a lot of information regarding Ethernet, NWay, MII, | |
2294 | etc. at www.scyld.com. | |
2295 | ||
2296 | -- END -- |