This bug has been copied from bug #637764 and has been proposed to be backported to 5.5 z-stream (EUS).
in kernel 2.6.18-194.21.1.el5 linux-2.6-net-bonding-fix-igmp-report-on-slave-during-failover.patch
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2010-0839.html
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: In an active/backup bonding network interface with vlans on top of it, when a link failed over, it took a minute for the multicast domain to be rejoined. This was caused by the driver not sending any IGMP join packets. With this update, the driver sends IGMP join packets and the multicast domain is rejoined immediately.