Subject: Re: [magma] Should a snooping switch proxy or forward IGMP queries?

From: Frank Solensky <[email-masked]>
Date: Mon, 21 Feb 2005 09:56:06 -0500

On Tue, 2005-01-18 at 11:08 -0500, [email-masked] wrote:
> Consider an IGMP snooping switch with static routers configured on
> ports 1 and 2 which receives a general Query on port 5.  Should that
> query be forwarded (intact) or proxied (with a source address of
> 0.0.0.0) to ports 3, 4, 6, etc.?  It seems intuitive that it should or
> the router out port 5 will never know about members that may be out
> port 3, etc. but "Considerations" doesn't seem to say so.

(Sorry for delay in responding..)

It depends on what you mean by "static routers configured..".

The snooping _switch_ is mostly a layer 2 device that looks into layer 3
for things of interest.  A static route to 0.0.0.0/0 doesn't come into
play in this case since it looks only at the layer 2 address to make its
forwarding decisions.  The only exception I can think of is if some
other device on the network were to be pointing at the switch as if it
were a router.  In that case, it's no longer a switch.

If you're thinking of a static route that directs all unrecognized MAC
addresses to ports 1 and 2: snooping becomes moot.  Your static route is
telling the switch what to do with all unrecognized traffic.

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