DELL 8132 ユーザーズマニュアル

IGMP Commands

The Router-Alert option is not required by default.

Global Configuration

If the router alert check is enabled, IGMP frames without the router-alert 

option in the IP header are discarded early in the processing of IGMP packets. 

If all the multicast hosts in the network include the router alert option as 

required by RFC 2236 and RFC 3376, then enabling this check can reduce 

the load on the system.

ip igmp router-alert-check

2CSPC4.X8100-SWUM102.book  Page 1029  Friday, March 15, 2013  8:56 AM