[c-nsp] Multicast flooding on vlan in L3 switch

[Tim Stevenson]

What is the group address you are joining?

Cat switches like the 3560 should constrain to just the L2 ports that 
have joined even when the vlan interface is an OIF at L3.

Tim

At 09:54 AM 10/4/2007 +0200, Wyatt Mattias Ishmael Jovial Gyllenvarg observed:
>Hi all
>
>We have an issue we cant find any reference too.
>
>We have a 3560G that gets a "ip pim spare-mode" mutlicast feed.
>
>There is a Vlan X on the switch with a few access ports.
>When a join comes from one of these ports all ports in the vlan are flooded.
>We have tried several IGMP SNOOPING configurations but with no reslut.
>
>We have assumed that this is normal as the L3 multicast process sees
>this as one interface and does not act like a L2 switch would. ie the
>IGMP snooping is ignored.
>
>How do we get around this?
>
>Best regards
>
>Mattias Gyllenvarg
>Omnitron
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Tim Stevenson, tstevens at cisco.com
Routing & Switching CCIE #5561
Technical Marketing Engineer, Data Center BU
Cisco Systems, http://www.cisco.com
IP Phone: 408-526-6759
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