From: Herbert Maosa (asawilunda@googlemail.com)
Date: Thu Aug 23 2007 - 08:27:19 ART
I dont think it is complicated, I have not seen it behave any differently
from a router. In order to receive the traffic for the group, the loopback
interface must be added to the OIL. PIM is what builds the tree, so the
interface can not be added to the OIL unless you enable PIM on the
interface apart from using ip igmp joinj group. This behavior is the same
even from routers and is expected.
Then, if you are using PIM sparse mode, you need an RP. You will learn the
RP either statically or dynamically.
Once you learn the RP, you need to have reachability to both the RP and the
multicast source. You must therefore have some good routing on the switch to
give you this reachability inorder for the RPF checks to pass.
It looks to me like your switch is behaving as it should, unless I am
missing something.
Herbert.
On 8/23/07, Bit Gossip <bit.gossip@chello.nl> wrote:
>
> Experts,
> in many practice-labsit is required to configure one of the Cat3550 as
> multicast receiver for certain groups so that it replies to ping send to
> that
> particular group. This is done using 'ip igmp join-group 224.224.224.224'
> but
> to me this never works, see below.
>
> If I configure only 'ip igmp join-group 224.224.224.224' I notice from
> neighbor routers that the Cat3550 doesn't actually send any IGMP report
> for
> the group.
>
> So I enable 'ip multicast-routing' and 'ip sparse-mode' on the interface
> and
> at this point IGMP reports are finally sent.
>
> But still Cat3550 doesn't reply to ping complaing of not being able to RPF
> to
> the RP, which makes sense because no RP has been defined. Actually I don't
> want to define any RP on this switch because I want it to behave just like
> a
> dumb host and not like a multicast router.
>
> S4#ping 224.224.224.224
> Type escape sequence to abort.
> Sending 1, 100-byte ICMP Echos to 224.224.224.224, timeout is 2 seconds:
> 1d01h: IP(0): MAC sa=000b.464a.4180 (Vlan106), IP last-hop=10.1.68.10
> 1d01h: IP(0): IP tos=0x0, len=100, id=10, ttl=254, prot=1
> 1d01h: IP(0): s=10.1.68.10 (Vlan106) d=224.224.224.224 id=10, ttl=254,
> prot=1,
> len=114(100), RPF lookup failed for source or RP.
>
> I tried to put a static mroute but it doesn't fix the problem, so to make
> it
> happy I configure itself as a dummy RP and finally it replies to the
> multicast
> ping
>
> S4#ping 224.224.224.224
> Type escape sequence to abort.
> Sending 1, 100-byte ICMP Echos to 224.224.224.224, timeout is 2 seconds:
> Reply to request 0 from 10.1.68.10, 4 ms
>
> An alternative to configuring a dummy RP is to configure the interface in
> dense mode; this also works.
>
> Is it really so complicated to convince this Cat 3550 to reply to the ping
> or
> I am missing something?
> What about Cat3560, I can not test it because I don't have it?
>
> S4#show ver
> Cisco IOS Software, C3550 Software (C3550-IPSERVICESK9-M), Version
> 12.2(25)SEE3, RELEASE SOFTWARE (fc2)
>
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-- Kindest regards, hm
This archive was generated by hypermail 2.1.4 : Sat Sep 01 2007 - 11:32:12 ART