Any disadvantages to enabling IGMP Snooping on a WLC?

Unanswered Question
Sep 15th, 2010

I am running 6.0.199 code on multiple WLCs. I am running multicast traffic to the wireless clients and have enabled IGMP Snooping on the WLCs. It seems to me that IGMP Snooping is a good thing and should always be enabled. Is there any reason NOT to enable IGMP Snooping?  What are the disadvantages of enabling IGMP Snooping?

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Sharath Kattema... Fri, 09/17/2010 - 00:06

In controller software release 4.2, IGMP snooping is introduced to better direct multicast packets. When this feature is enabled, the controller gathers IGMP reports from the clients, processes the reports, creates unique multicast group IDs (MGIDs) from the IGMP reports after checking the Layer 3 multicast address and the VLAN number, and sends the IGMP reports to the infrastructure switch. The controller sends these reports with the source address as the interface address on which it received the reports from the clients.
The controller then updates the access point MGID table on the AP with the client MAC address. When the controller receives multicast traffic for a particular multicast group, it forwards it to all the APs. However, only those APs that have active clients listening or subscribed to that multicast group send multicast traffic on that particular WLAN. IP packets are forwarded with an MGID that is unique for an ingress VLAN and the destination multicast group. Layer 2 multicast packets are forwarded with an MGID that is unique for the ingress interface.

Note: IGMP snooping is not supported on the 2000 series controllers, the 2100 series controllers, or the Cisco Wireless LAN Controller Network Module for Cisco Integrated Services Routers.

There are few Know issue with snooping enabeld ;

Example ; Directed broadcast not working when igmp snooping enabled : Fixed in 7.0(98)

Most of the other issue are fixed in latest 6.0 and 7.0 codes

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