From: Wollmann, Bruno RQHR (Bruno.Wollmann@rqhealth.ca)
Date: Wed Nov 14 2007 - 11:17:24 ART
Correct. IP IGMP JOIN-GROUP <group address> turns the router into a
multicast receiver/host which doesn't require multicast routing enabled
on the router or PIM enabled on the interface. It's just like a PC that
joins a multicast group. That PC doesn't have to route multicast
packets, it just wants to receive them.
I can't get the switches to behave the same way.
Thanks
Bruno
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Gregory Gombas
Sent: November 14, 2007 7:49 AM
To: Wollmann, Bruno RQHR
Cc: Cisco certification
Subject: Re: Multicast on 3550/3560
I thought routers also needed PIM enabled in order to enable multicast
processing on the interface. Are you saying that is not the case? Is
that documented somewhere?
Thanks,
Greg
On Nov 13, 2007 11:44 PM, Wollmann, Bruno RQHR
<Bruno.Wollmann@rqhealth.ca> wrote:
> Hello GS,
>
> Has anyone other than me had trouble getting a 3550 or 3560 to reply
> to pings after using the IP IGMP JOIN-GROUP command? My switches
> won't reply to pings unless I enable multicast routing on them and
> enable PIM on the interface. My routers only need to join the group
> to reply to pings. I don't have to enable multicast routing or PIM.
>
> My setup is simple. OSPF is running on all 4 devices so that r1 knows
> about the r3,r5,sw1 network and sw1 and r5 know about the r1,r3
network.
> I started off with more complicated configs as I was doing practice
> labs and was having problems getting them to work. To help
> troubleshoot, I simplified things. r1 and r3 are running PIM DENSE on
their interfaces.
> Even when I send a ping from r3, r5 is the only device to reply, sw1
> does not.
>
> r1----p2pserial----r3-------sw1
> |-----r5
>
> Is this normal behaviour for the switches. I've read the doc cd and I
> think my setup should work without having to enable multicast routing
> on the switches. I've tried this with routed interfaces and svi
> interfaces on the switches. What am I missing?
>
> http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3560/12240se/sc
> g/
> swmcast.htm
>
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