VLAN on bonded NICs with "fail_over_mac=active" not working after a failover

This document (7011417) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10 Service Pack 4
SUSE Linux Enterprise Server 11 Service Pack 1
SUSE Linux Enterprise Server 11 Service Pack 2

Situation

A VLAN configured on top of a bond interface in an active-backup mode with the option "fail_over_mac=active" does not receive the new MAC address of the active interface after the failover operation.

Option "fail_over_mac=active" is set in the parameter BONDING_OPTS in the file /etc/sysconfig/network-scripts/ifcfg-bond0.

It indicates that the MAC address of the bond should be the same as the MAC of the currently active slave. During a failover the bond receives the new MAC address of a currently active slave interface. The MAC address of the slave is not changed. VLAN keeps the old MAC address so that it is not accessible through a new active slave.

Resolution

SUSE Linux Enterprise Server 11 SP1
SUSE Linux Enterprise Server 11 SP2

It is recommended to use "fail_over_mac=active" option only for the devices that cannot change their MAC address.

For the Ethernet devices the option "fail_over_mac=follow" should be used. At failover time the MAC address of the bond is assigned to the new active slave and its old address is assigned to the formerly active slave. VLAN configured on top of the bond retains the same address.

Using "fail_over_mac=active" on Ethernet devices has other drawbacks, e.g. if gratuitous ARP is lost or incorrectly processed after a failover, bond is not accessible until it sends a packet.

SUSE Linux Enterprise Server 10 SP4

There is no option "fail_over_mac=follow" in SLES10 SP4. The issue is resolved in the kernel 2.6.16.60-0.93, which can be installed from the update channels.

Additional Information

Disclaimer

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