bonding: document the new _arp options for arp_validate
CC: Jay Vosburgh <fubar@us.ibm.com> CC: Andy Gospodarek <andy@greyhouse.net> Signed-off-by: Veaceslav Falico <vfalico@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -270,16 +270,15 @@ arp_ip_target
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arp_validate
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Specifies whether or not ARP probes and replies should be
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validated in any mode that supports arp monitoring. This causes
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the ARP monitor to examine the incoming ARP requests and replies,
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and only consider a slave to be up if it is receiving the
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appropriate ARP traffic.
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validated in any mode that supports arp monitoring, or whether
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non-ARP traffic should be filtered (disregarded) for link
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monitoring purposes.
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Possible values are:
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none or 0
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No validation is performed. This is the default.
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No validation or filtering is performed.
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active or 1
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@ -293,31 +292,68 @@ arp_validate
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Validation is performed for all slaves.
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For the active slave, the validation checks ARP replies to
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confirm that they were generated by an arp_ip_target. Since
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backup slaves do not typically receive these replies, the
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validation performed for backup slaves is on the ARP request
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sent out via the active slave. It is possible that some
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switch or network configurations may result in situations
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wherein the backup slaves do not receive the ARP requests; in
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such a situation, validation of backup slaves must be
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disabled.
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filter or 4
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The validation of ARP requests on backup slaves is mainly
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helping bonding to decide which slaves are more likely to
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work in case of the active slave failure, it doesn't really
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guarantee that the backup slave will work if it's selected
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as the next active slave.
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Filtering is applied to all slaves. No validation is
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performed.
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This option is useful in network configurations in which
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multiple bonding hosts are concurrently issuing ARPs to one or
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more targets beyond a common switch. Should the link between
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the switch and target fail (but not the switch itself), the
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probe traffic generated by the multiple bonding instances will
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fool the standard ARP monitor into considering the links as
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still up. Use of the arp_validate option can resolve this, as
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the ARP monitor will only consider ARP requests and replies
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associated with its own instance of bonding.
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filter_active or 5
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Filtering is applied to all slaves, validation is performed
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only for the active slave.
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filter_backup or 6
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Filtering is applied to all slaves, validation is performed
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only for backup slaves.
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Validation:
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Enabling validation causes the ARP monitor to examine the incoming
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ARP requests and replies, and only consider a slave to be up if it
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is receiving the appropriate ARP traffic.
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For an active slave, the validation checks ARP replies to confirm
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that they were generated by an arp_ip_target. Since backup slaves
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do not typically receive these replies, the validation performed
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for backup slaves is on the broadcast ARP request sent out via the
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active slave. It is possible that some switch or network
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configurations may result in situations wherein the backup slaves
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do not receive the ARP requests; in such a situation, validation
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of backup slaves must be disabled.
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The validation of ARP requests on backup slaves is mainly helping
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bonding to decide which slaves are more likely to work in case of
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the active slave failure, it doesn't really guarantee that the
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backup slave will work if it's selected as the next active slave.
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Validation is useful in network configurations in which multiple
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bonding hosts are concurrently issuing ARPs to one or more targets
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beyond a common switch. Should the link between the switch and
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target fail (but not the switch itself), the probe traffic
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generated by the multiple bonding instances will fool the standard
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ARP monitor into considering the links as still up. Use of
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validation can resolve this, as the ARP monitor will only consider
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ARP requests and replies associated with its own instance of
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bonding.
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Filtering:
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Enabling filtering causes the ARP monitor to only use incoming ARP
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packets for link availability purposes. Arriving packets that are
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not ARPs are delivered normally, but do not count when determining
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if a slave is available.
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Filtering operates by only considering the reception of ARP
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packets (any ARP packet, regardless of source or destination) when
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determining if a slave has received traffic for link availability
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purposes.
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Filtering is useful in network configurations in which significant
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levels of third party broadcast traffic would fool the standard
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ARP monitor into considering the links as still up. Use of
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filtering can resolve this, as only ARP traffic is considered for
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link availability purposes.
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This option was added in bonding version 3.1.0.
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