Subject: [pim] C-RP doubt!!!

From: "Ganapath" <[email-masked]>
Date: 12 Sep 2002 08:28:53 -0000

Hello,

I have the following doubts regarding PIM-SM working,

1. I am going through draft-ietf-pim-sm-bsr-02, suppose the 
scenario where new router has come up. i am unable to understand 
how exactly new router sends register message to RP of 
corresponding group if it gets multicast
traffic from directly connected source. coz it doesn't know who is 
RP for this multicast group.

2. If a router follows BSR technique to learn about RP to group 
mappings, How a router configured as candidate-rp would come to 
know that it should act as rp for those specific multicast groups 
only. my confusion is on what basis it it is going to fill c-rp 
advertisement message(group field).

Please let me know if I am not clear.

regards,
Ganapath
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From: Pavlin Radoslavov <[email-masked]>
Date: Thu, 12 Sep 2002 10:00:10 -0700

> RP for this multicast group.

It waits until it receives Bootstrap message(s) with the Cand-RP set
(or until it receives Cand-RP messages if it is elected as the BSR).
In the mean time it won't know the RP for the particular mcast
group, hence it won't send Registers.

> advertisement message(group field).

A Cand-RP would fill the Cand-RP Advertisement messages with all
group prefixes it is configured for. Filling-in a group prefix in a
Cand-RP Adv. message doesn't mean that it is _the_ RP for that
prefix; rather, it is a _candidate_ RP. Only after the Cand-RP Advs
are sent to the BSR, they are used to compose the Cand-RP set. This
set is propagated to all PIM-SM routers in the domain (inside the
Bootstrap messages by the BSR), and then each router will make the
decision by itself who is the RP for a particular group.

Hope that helps,
Pavlin