From: Jared Scrivener (jscrivener@ipexpert.com)
Date: Thu Jan 01 2009 - 17:40:34 ARST
If you aren't receiving a reply then go from router to router in your
network doing a "show ip mroute". Check that the incoming interface shown
for the (S,G) entry matches the path that the multicast packet should take
based on the outgoing interface for the same (S,G) entry on the router
closer to the source.
Presuming you've setup PIM correctly and each router knows the RP for that
group, chances are your issues will be a result of an RPF check failure (or
a missing IPv4 route).
Cheers,
Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener@ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
CiSco Champ
Sent: Wednesday, 31 December 2008 11:02 PM
To: joshua atterbury
Cc: Rado Vasilev; John Edom; ccielab@groupstudy.com
Subject: Re: Multiicast Troubleshooting
thanks for answering, it obviousely help me. if i am not recieving ping
reply, this can be because of PIM DR position in sagment ?
Regards
On Thu, Jan 1, 2009 at 7:54 AM, joshua atterbury
<joshuaatterbury@gmail.com>wrote:
> For your last question about pinging a multicast group.
>
> When you ping a multicast group, The router originates a ping request for
> all pim enabled loopbacks and the physical pim enabled interface.
>
> To check this scenario do a "debug ip mpacket" on a router then run the
> ping
> command, This will show you all the mcast ping packets, Beaware that if
> you
> are testing things like ttl thresholds etc then the results can be
> confusing
> at first, As the pings originated from the loopback will have their ttl
> value as 1 lower than the packet originated from the physical interface.
> Due
> to these packets being routed from the loopback to the physical interface.
>
> Hope this helps.
>
> Josh.
>
>
> On Thu, Jan 1, 2009 at 1:27 PM, Rado Vasilev <decklandv@gmail.com> wrote:
>
> > Hi,
> >>
> >> I am good in configuring Multicast but weak in it troubleshooting if
> >> devices
> >> are not giving required result. Anyone please tell me some commands and
> >> steps to identify cause of problem?
> >>
> >
> > usually problems are related to failed RPF check.
> >
> >>
> >>
> >> Tell me for troubleshooting, i enable "debug ip mrouting", "debug ip
> >> mpacket" but don't get any debug report when ping multicast group what
> >> would
> >> be reason ?
> >>
> >
> > configure 'no ip mroute-cache' on the interfaces first.'
> >
> >
> >> Another thing when we ping a multicast group, will source ip be of
> >> loopback
> >> interface ?
> >>
> >
> >
> > all ifaces
> >
> >
> >
> >
> > regards,
> > rado
> >
> >
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> >
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