From: Brian McGahan (bmcgahan@internetworkexpert.com)
Date: Tue Mar 29 2005 - 12:35:19 GMT-3
Correct. It is simply that when you do a standard ping to a
multicast address the router sends it out all interfaces. If you want
to limit it to a specific interface use an extended ping.
HTH,
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987 x 705
Outside US: 775-826-4344 x 705
24/7 Support: http://forum.internetworkexpert.com
Live Chat: http://www.internetworkexpert.com/chat/
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Dillon Yang
> Sent: Tuesday, March 29, 2005 6:05 AM
> To: simon hart
> Cc: Group Study
> Subject: Re: Pinging Multicast group
>
> 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
> > --
> > No virus found in this outgoing message.
> > Checked by AVG Anti-Virus.
> > Version: 7.0.308 / Virus Database: 266.8.4 - Release Date:
27/03/2005
> >
> >
This archive was generated by hypermail 2.1.4 : Sun Apr 03 2005 - 17:56:54 GMT-3