Commit 52f65ef3 authored by Veaceslav Falico's avatar Veaceslav Falico Committed by David S. Miller

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: default avatarVeaceslav Falico <vfalico@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 896149ff
......@@ -270,16 +270,15 @@ arp_ip_target
arp_validate
Specifies whether or not ARP probes and replies should be
validated in any mode that supports arp monitoring. 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.
validated in any mode that supports arp monitoring, or whether
non-ARP traffic should be filtered (disregarded) for link
monitoring purposes.
Possible values are:
none or 0
No validation is performed. This is the default.
No validation or filtering is performed.
active or 1
......@@ -293,31 +292,68 @@ arp_validate
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.
The validation of ARP requests on backup slaves is mainly
helping bonding to decide which slaves are more likely to
work in case of the active slave failure, it doesn't really
guarantee that the backup slave will work if it's selected
as the next active slave.
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.
filter or 4
Filtering is applied to all slaves. No validation is
performed.
filter_active or 5
Filtering is applied to all slaves, validation is performed
only for the active slave.
filter_backup or 6
Filtering is applied to all slaves, validation is performed
only for backup slaves.
Validation:
Enabling validation 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.
For an 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 broadcast 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.
The validation of ARP requests on backup slaves is mainly helping
bonding to decide which slaves are more likely to work in case of
the active slave failure, it doesn't really guarantee that the
backup slave will work if it's selected as the next active slave.
Validation 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
validation can resolve this, as the ARP monitor will only consider
ARP requests and replies associated with its own instance of
bonding.
Filtering:
Enabling filtering causes the ARP monitor to only use incoming ARP
packets for link availability purposes. Arriving packets that are
not ARPs are delivered normally, but do not count when determining
if a slave is available.
Filtering operates by only considering the reception of ARP
packets (any ARP packet, regardless of source or destination) when
determining if a slave has received traffic for link availability
purposes.
Filtering is useful in network configurations in which significant
levels of third party broadcast traffic would fool the standard
ARP monitor into considering the links as still up. Use of
filtering can resolve this, as only ARP traffic is considered for
link availability purposes.
This option was added in bonding version 3.1.0.
......
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