From: Dillon Yang (gzdillon@hotmail.com)
Date: Tue Mar 29 2005 - 09:04:52 GMT-3
Hi, simon:
I have met the same situation. Did you use the extended PING?
The IOS will ask you "which interface?[all]", and you can just press "enter" or no choice.
Maybe it just is allowed by "all".
dillon
----- Original Message -----
From: "simon hart" <simon.hart@btinternet.com>
To: "ccie2be" <ccie2be@nyc.rr.com>; "'Group Study'" <ccielab@groupstudy.com>
Sent: Tuesday, March 29, 2005 7:24 PM
Subject: RE: Pinging Multicast group
> Hi Tim,
>
> If that is the case then perhaps you can help out with the following.
>
> The output here is from a router with no multicast enabled
>
> Rack1R6#sh ip mroute
> IP Multicast Routing Table
> Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
> L - Local, P - Pruned, R - RP-bit set, F - Register flag,
> T - SPT-bit set, J - Join SPT, M - MSDP created entry,
> X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
> U - URD, I - Received Source Specific Host Report, Z - Multicast
> Tunnel
> Y - Joined MDT-data group, y - Sending to MDT-data group
> Outgoing interface flags: H - Hardware switched
> Timers: Uptime/Expires
> Interface state: Interface, Next-Hop or VCD, State/Mode
>
> Hence no entries in the Mcast table.
>
> Now if I ping and debug ip packet on this router I will get the following
> output
>
> Rack1R6#ping 239.9.9.9
>
> Type escape sequence to abort.
> Sending 1, 100-byte ICMP Echos to 239.9.9.9, timeout is 2 seconds:
> .
> Rack1R6#debug ip packet
> IP packet debugging is on
> Rack1R6#ping 239.9.9.9
>
> Type escape sequence to abort.
> Sending 1, 100-byte ICMP Echos to 239.9.9.9, timeout is 2 seconds:
>
> *Mar 1 03:52:41.510: IP: s=54.1.4.6 (local), d=239.9.9.9 (Serial0/0), len
> 100, sending broad/multicast
> *Mar 1 03:52:41.514: IP: s=141.1.36.6 (local), d=239.9.9.9
> (FastEthernet1/0), len 100, sending broad/multicast
> *Mar 1 03:52:41.514: IP: s=150.1.6.6 (local), d=239.9.9.9 (Loopback0), len
> 100, sending broad/multicast
> *Mar 1 03:52:41.518: IP: s=150.1.6.6 (Loopback0), d=239.9.9.9, len 100,
> unroutable.
>
> I think that as you can see the packet has been sent out of each interface
> that is currently 'up'.
>
> Similarly, if I conduct a similar exercise from a multicast enabled router
> the ping will go out of every interface, including the ones referenced
> within the Mcast routing table.
>
> Has me scratching my head a bit, but it must have something to do with a
> ping not acting in the same way as a multicast stream. That is the the ping
> is not trying to join a group as such. I think what is happening is that
> the ping is sent out of every interface in the hope that it will hit a
> router that has a tree entry for that group, that router would have to be
> directly connected.
>
> Simon
>
> -----Original Message-----
> From: ccie2be [mailto:ccie2be@nyc.rr.com]
> Sent: 29 March 2005 12:17
> To: 'simon hart'; 'Group Study'
> Subject: RE: Pinging Multicast group
>
>
> Simon,
>
> Actually, I think that's not true.
>
> The ping will only go out those interfaces listed in the OIL (Outgoing
> Interface List0 which you can see by doing a show ip mroute.
>
> Tim
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> simon hart
> Sent: Tuesday, March 29, 2005 4:09 AM
> To: Group Study
> Subject: Pinging Multicast group
>
> Hi all,
>
> Can anyone enlighten me.
>
> Whenever I ping a multicast group from a router, then the packet gets sent
> out of all interfaces, even if an *,g or s,g exits for that group on the
> router. Why does this behaviour occur?
>
> Thanks
>
> Simon
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