[Xorp-users] Re: Newbie Xorp & m'cast problem

[edrt]

>
>The second IGMP leave message is actually originated from the STP ROOT switch
>to help the switching network quickly rebuilds the IGMP snooping entry after
>spanning tree reconfigures.
>
>ref "Typically, if a topology change occurs, ...", at
> http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_1_11/config/multi.htm#1049520
>
>
>Eddy
>
>

More relevant information could be found at: draft-ietf-magma-snoop-12.txt/2.1.1/4)


 	 4)  An IGMP snooping switch should be aware of link layer topology
         changes caused by Spanning Tree operation. When a port is
         enabled or disabled by Spanning Tree, a General Query may be
         sent on all active non-router ports in order to reduce network
         convergence time.  Non-Querier switches should be aware of
         whether the Querier is in IGMPv3 mode. If so, the switch should
         not spoof any General Queries unless it is able to send an
         IGMPv3 Query that adheres to the most recent information sent
         by the true Querier. In no case should a switch introduce a
         spoofed IGMPv2 Query into an IGMPv3 network, as this may create
         excessive network disruption.

         If the switch is not the Querier, it should use the 'all-zeros'
         IP Source Address in these proxy queries (even though some
         hosts may elect to not process queries with a 0.0.0.0 IP Source
         Address).  When such proxy queries are received, they must not
         be included in the Querier election process.



Eddy