We use EIGRP ;-) not IGRP although the same applies, consider the following
:
After a pair of routers become neighbors, they will send routing updates
(and other packets) to one another using a reliable multicast scheme. For
example, if router one has a series of packets which must be transmitted to
routers two, three, and four, such as a routing table update, it will send
the first packet to the EIGRP multicast address, 224.0.0.10, and wait for a
acknowledgment from each of it's neighbors on it's ethernet interface (in
this case routers two, three, and four). Let's assume that routers two and
four do answer, but router three does not.
Router one will wait until the multicast flow timer expires on the ethernet
interface, then send out a special packet, a sequence tlv, telling router
three not to listen to any further multicast packets from router one, then
will continue transmitting the remainder of the update packets as multicast
to all other routers on the network. The sequence tlv indicates an
out-of-sequence multicast packet. Those routers not listed in the packet
enter conditional receive (CR) mode and continue listening to multicast.
While there are some routers in this mode, the conditional receive bit will
be set in multicast packets. In this case, router one will send out a
sequence tlv with router three listed, so routers two and four will continue
listening to further multicast updates.
Cheers
Steve
> -----Original Message-----
> From: Robert E. Seastrom [mailto:rs@seastrom.com]
> Sent: 16 May 2001 16:59
> To: Rafael A. Reta Rodriguez
> Cc: cisco-nsp@puck.nether.net
> Subject: Re: Strange trafic to 224.0.0.10
>
>
> "Rafael A. Reta Rodriguez" <rafareta@icave.com.mx> writes:
>
> > Why does my Cisco 3640 and 3810 send information to address 224.0.0.10?
> >
> > I checked the sh ru and there is no line with this IP number.
>
> You're running IGRP, correct?
>
> rs@valhalla [5] % host 224.0.0.10
> 10.0.0.224.IN-ADDR.ARPA domain name pointer IGRP-ROUTERS.MCAST.NET
> rs@valhalla [6] %
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