Alcatel Carrier Internetworking Solutions 8800 User Manual

Troubleshooting IP Multicast Switching (IPMS)

Troubleshooting a Device that Drops Out of an IP Multicast Stream

OmniSwitch Troubleshooting Guide

page 14-6

You may also have a misconfigured or malfunctioning ip multicast static-querier. In the show ip 
multicast queriers command, look for Type of “Static” and check to see if the IP addresses configured 
exist and are functioning properly.

Also mentioned was that if a group membership expires it may be because it isn’t on an IP VLAN. This is 
probably due to a querying problem. IPMS cannot send IGMP queries on a VLAN that doesn’t have an IP 
address, but you can still have another switch in the same VLAN that is configured for IP and is querying. 
In this case, things will work because there is still a querier present, even if it is not a local switch. 
Remember that queriers are required for the re-solicitation of IGMP clients. Queries are sent every 120 
seconds, to which all clients must respond with a membership report.

Also check the flood limits (show interfaces flood rate) to see if the switch is dropping packets due to 
them being over the limit:

You want to see Flood only in an IPMS environment. If you see:

-> show interfaces flood rate
Slot/Port peak 

rate(Mb/second) Enable

-----------+----------------------+---------------
4/1 47 

Flood/multicast

4/2 47 

Flood/multicast

4/3 47 

Flood/multicast

You will want to set it back to Flood only via:

-> interfaces 4 flood

Note that this is by slot, not by VLAN.