2 Nics / 2 Networks / Multicast traffic


ATCA Chassis with a Radisys ATCA 4300 Processor Board running RHEL 5.3

There are 4 NICS on the backplane of the ATCA4300 which are visible to the host.

eth2 + eth3 are slaves to bond0.100 which tags vlan 100 (also subnetted to be on the network)
eth4 + eth5 are slaves to bond1.200 which tags to vlan 200 (subnetted to be on the network)

I have a requirement for the host to use both subnets, where it will join multicast groups on each.

The  problem is that I need to add a route to the host routing table for the (IGMP V3 Join Message),  (or i can add a default route) but I can only add it to one Interface.  Technically, I can route it to both interfaces, but  it will always pick the first match on the routing table.

Is there a work around for this?  How do I get the IGMP Join messages to the correct subnet?

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> Technically, I can route it to both interfaces, but  it will always pick the first match on the routing table.
What application are you using?

"Interface selection.
Hosts attached to more than one network should provide a way for applications to decide which network interface will be used to output the transmissions. If not specified, the kernel chooses a default one based on system administrator's configuration. "

If possible to choose interface - use 2 instances of your application for every interface.
If not, you may try to use nemesis (packet injection tool) for sending IGMP join on specific interface: http://nemesis.sourceforge.net/manpages/nemesis-igmp.1.html
then you may tell kernel to receive all multicast packets ('ip link set dev ethX.Y allmulticast on')

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