From: Wollmann, Bruno RQHR (Bruno.Wollmann@rqhealth.ca)
Date: Thu Nov 08 2007 - 01:29:19 ART
The document I'm reading right now while studying multicast and auto-rp
says that "all Cisco routers automatically join the Cisco-discovery
(224.0.1.40) group in order to receive group-to-RP mapping information
being multicast by the Mapping Agents in the network". The mapping
agent then advertises the C-RP with the highest IP address as the RP.
My question is, why bother with this step? Why don't the routers just
join the RP-announcement (224.0.1.39) group and learn the candidate RP's
right from the candidates themselves and then chose the one with the
highest IP address on their own. Why not learn it right from "the
horse's mouth" rather than a mapping Agent?
Anyone know the answer or have a logical explanation?
If you want to read what I'm reading for yourself check out page #7 at
ftp://ftp-eng.cisco.com/ipmulticast/training/Module6.pdf
thanks
Bruno
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