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authorJay Vosburgh <fubar@us.ibm.com>2006-09-23 08:54:53 +0400
committerJeff Garzik <jeff@garzik.org>2006-09-26 04:08:09 +0400
commitf5b2b966f032f22d3a289045a5afd4afa09f09c6 (patch)
treecb3c505d8f444438bed09353788f6c96150f68ad /Documentation/networking
parent70298705bb29fb7982b85089adf17cd37b94baa7 (diff)
downloadlinux-f5b2b966f032f22d3a289045a5afd4afa09f09c6.tar.xz
[PATCH] bonding: Validate probe replies in ARP monitor
Add logic to check ARP request / reply packets used for ARP monitor link integrity checking. The current method simply examines the slave device to see if it has sent and received traffic; this can be fooled by extraneous traffic. For example, if multiple hosts running bonding are behind a common switch, the probe traffic from the multiple instances of bonding will update the tx/rx times on each other's slave devices. Signed-off-by: Jay Vosburgh <fubar@us.ibm.com> Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/bonding.txt59
1 files changed, 59 insertions, 0 deletions
diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
index afac780445cd..dc942eaf490f 100644
--- a/Documentation/networking/bonding.txt
+++ b/Documentation/networking/bonding.txt
@@ -192,6 +192,17 @@ or, for backwards compatibility, the option value. E.g.,
arp_interval
Specifies the ARP link monitoring frequency in milliseconds.
+
+ The ARP monitor works by periodically checking the slave
+ devices to determine whether they have sent or received
+ traffic recently (the precise criteria depends upon the
+ bonding mode, and the state of the slave). Regular traffic is
+ generated via ARP probes issued for the addresses specified by
+ the arp_ip_target option.
+
+ This behavior can be modified by the arp_validate option,
+ below.
+
If ARP monitoring is used in an etherchannel compatible mode
(modes 0 and 2), the switch should be configured in a mode
that evenly distributes packets across all links. If the
@@ -213,6 +224,54 @@ arp_ip_target
maximum number of targets that can be specified is 16. The
default value is no IP addresses.
+arp_validate
+
+ Specifies whether or not ARP probes and replies should be
+ validated in the active-backup mode. This causes the ARP
+ monitor to examine the incoming ARP requests and replies, and
+ only consider a slave to be up if it is receiving the
+ appropriate ARP traffic.
+
+ Possible values are:
+
+ none or 0
+
+ No validation is performed. This is the default.
+
+ active or 1
+
+ Validation is performed only for the active slave.
+
+ backup or 2
+
+ Validation is performed only for backup slaves.
+
+ all or 3
+
+ Validation is performed for all slaves.
+
+ For the active slave, the validation checks ARP replies to
+ confirm that they were generated by an arp_ip_target. Since
+ backup slaves do not typically receive these replies, the
+ validation performed for backup slaves is on the ARP request
+ sent out via the active slave. It is possible that some
+ switch or network configurations may result in situations
+ wherein the backup slaves do not receive the ARP requests; in
+ such a situation, validation of backup slaves must be
+ disabled.
+
+ This option is useful in network configurations in which
+ multiple bonding hosts are concurrently issuing ARPs to one or
+ more targets beyond a common switch. Should the link between
+ the switch and target fail (but not the switch itself), the
+ probe traffic generated by the multiple bonding instances will
+ fool the standard ARP monitor into considering the links as
+ still up. Use of the arp_validate option can resolve this, as
+ the ARP monitor will only consider ARP requests and replies
+ associated with its own instance of bonding.
+
+ This option was added in bonding version 3.1.0.
+
downdelay
Specifies the time, in milliseconds, to wait before disabling