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bonding: Add "follow" option to fail_over_mac

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Add a "follow" selection for fail_over_mac.  This option
causes the MAC address to move from slave to slave as the active
slave changes.  This is in addition to the existing fail_over_mac option
that causes the bond's MAC address to change during failover.

	This new option is useful for devices that cannot tolerate
multiple ports using the same MAC address simultaneously, either
because it confuses them or incurs a performance penalty (as is the
case with some LPAR-aware multiport devices).  Because the MAC of the
bond itself does not change, the "follow" option is slightly more
reliable during failover and doesn't change the MAC of the bond during
operation.

	This patch requires a previous ARP monitor change to properly
handle RTNL during failovers.

Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
This commit is contained in:
Jay Vosburgh 2008-05-17 21:10:14 -07:00 • committed by Jeff Garzik
parent b2220cad58
commit 3915c1e863
4 changed files with 227 additions and 84 deletions
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86
Documentation/networking/bonding.txt
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@ -289,35 +289,73 @@ downdelay
fail_over_mac
Specifies whether active-backup mode should set all slaves to
the same MAC address (the traditional behavior), or, when
enabled, change the bond's MAC address when changing the
active interface (i.e., fail over the MAC address itself).
the same MAC address at enslavement (the traditional
behavior), or, when enabled, perform special handling of the
bond's MAC address in accordance with the selected policy.
Fail over MAC is useful for devices that cannot ever alter
their MAC address, or for devices that refuse incoming
broadcasts with their own source MAC (which interferes with
the ARP monitor).
Possible values are:
The down side of fail over MAC is that every device on the
network must be updated via gratuitous ARP, vs. just updating
a switch or set of switches (which often takes place for any
traffic, not just ARP traffic, if the switch snoops incoming
traffic to update its tables) for the traditional method. If
the gratuitous ARP is lost, communication may be disrupted.
none or 0
When fail over MAC is used in conjuction with the mii monitor,
devices which assert link up prior to being able to actually
transmit and receive are particularly susecptible to loss of
the gratuitous ARP, and an appropriate updelay setting may be
required.
This setting disables fail_over_mac, and causes
bonding to set all slaves of an active-backup bond to
the same MAC address at enslavement time. This is the
default.
A value of 0 disables fail over MAC, and is the default. A
value of 1 enables fail over MAC. This option is enabled
automatically if the first slave added cannot change its MAC
address. This option may be modified via sysfs only when no
slaves are present in the bond.
active or 1
This option was added in bonding version 3.2.0.
The "active" fail_over_mac policy indicates that the
MAC address of the bond should always be the MAC
address of the currently active slave. The MAC
address of the slaves is not changed; instead, the MAC
address of the bond changes during a failover.
This policy is useful for devices that cannot ever
alter their MAC address, or for devices that refuse
incoming broadcasts with their own source MAC (which
interferes with the ARP monitor).
The down side of this policy is that every device on
the network must be updated via gratuitous ARP,
vs. just updating a switch or set of switches (which
often takes place for any traffic, not just ARP
traffic, if the switch snoops incoming traffic to
update its tables) for the traditional method. If the
gratuitous ARP is lost, communication may be
disrupted.
When this policy is used in conjuction with the mii
monitor, devices which assert link up prior to being
able to actually transmit and receive are particularly
susecptible to loss of the gratuitous ARP, and an
appropriate updelay setting may be required.
follow or 2
The "follow" fail_over_mac policy causes the MAC
address of the bond to be selected normally (normally
the MAC address of the first slave added to the bond).
However, the second and subsequent slaves are not set
to this MAC address while they are in a backup role; a
slave is programmed with the bond's MAC address at
failover time (and the formerly active slave receives
the newly active slave's MAC address).
This policy is useful for multiport devices that
either become confused or incur a performance penalty
when multiple ports are programmed with the same MAC
address.
The default policy is none, unless the first slave cannot
change its MAC address, in which case the active policy is
selected by default.
This option may be modified via sysfs only when no slaves are
present in the bond.
This option was added in bonding version 3.2.0. The "follow"
policy was added in bonding version 3.3.0.
lacp_rate