Multicast - IGMP querier

[asieber]

Hi,

I have a question regarding multicast. Our developers plan to deploy a multicast application in on of our DMZ´s.

Unfortunately the application generates a lot of sync traffic and this fills up all interfaces in that vlan, because igmp snooping is not working on the switches. As far as i can see this is because there is no IGMP querier on that network.

Can someone tell me how I can configure our PA-5020 to be a igmp querier in that network? We do not want to route that multicast traffic, we just want the switch to limit the traffic to the hosts that joined the multicast group.

Thanks,

Alex

[mikand]

What kind of switch is this (model and perhaps firmware version)?

Because if IGMP snooping in the switch is disabled then multicast packets will be handled as broadcast and flooded to all interfaces which belongs to the same VLAN except the interface which the packet arrived at.

I have not dug into how the IGMP snooping will perform if there is no IGMP querier available but that sound somewhat odd to me that it would start to flood the packets as broadcast just because of that. Perhaps there is some setting for the IGMP snooping in your switch which can take control of this behaviour?

From Allied Telesyn docs:

"
When IGMP snooping is enabled, the switch listens to IGMP membership reports, queries, and leave messages to identify which ports are members of multicast groups. Multicast traffic is then forwarded only to ports that are members of the multicast group.
"

which gives if there are no members the traffic will be dropped by the switch (not forwarded at all).

In the case of Allied Telesyn there is also settings for which multicast addresses the IGMP snooping should act on (all, multicastrouter, default or ip) - perhaps this is a mismatch between your switch and your developers?

You can also often configure the IGMP in the switch statically (as workaround) which will force the switch to forward a particular multicast address to specific interfaces (which should avoid having your other interfaces being flooded).

[asieber]

we use Nortel / Avaya ERS 55xx as edge switches and ERS-8300 as CoreSwitches.

According to our network staff the switches need an igmp querier in the vlan for snooping to work.

They are able to define which multicast groups can flood the network and wich not.

But no static multicast port membership.