-------- Original Message -------- Subject: Re: [Xorp-users] join messages not sent out (from IGMP to PIM) Date: Thu, 08 Dec 2005 12:04:49 -0800 From: Pavlin Radoslavov pavlin@icir.org To: Daniel Sievers sievers@hilton.rwth-aachen.de CC: Pavlin Radoslavov pavlin@icir.org

Hrmm... and what happens in such a setup:

LAN (with Multicast receivers) <-------> xorp DR <----> PIM-SM Router A<----> non-PIM aware Switch <------> PIM-SM Router B

How can the non-PIM aware switch perform IGMP Snooping if Router A and B communicate through PIM only? It would have to forward all multicast traffic, which would be bad if there were other ports on that switch with no multicast receivers.

The most efficient solution would be PIM snooping: ttp://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/swcg/snooppim.htm

If the switch is not PIM-aware, then PIM-SM Router A should be the router that originates IGMP Join messages for each group joined via PIM-SM. Doing something like this was already discussed on the PIM mailing list few months ago (see the following email and the follow-ups): http://www1.ietf.org/mail-archive/web/pim/current/msg00483.html

However, so far it is only an idea and there is no a document to describe it.

Wouldn't it be good if xorp had at least an option to forward IGMP Reports from the LAN? (and better also reply to IGMP Queries from the outside with all groups subscribed to on the inside LAN)

To do something like this would require XORP to implement IGMP snooping. Implementing IGMP snooping is on our TODO list, but it is a relatively low priority task and it may take a while until it is implemented.

P.S.: Should we take this back to the mailinglist? I missed CCing that the last time.

As you wish.

Pavlin