Re: Backup RP

From: Ben (bmunyao@gmail.com)
Date: Fri Jul 20 2007 - 07:02:40 ART


Kirit,

Here are a couple of examples that i hope address your question.

R1---------------R2----------------R3
R1 loopback0:150.1.1.1
R2 loopback0:150.1.2.2
R3 loopback0:150.1.3.3

Example1-AutoRP

R1: ip pim send-rp-announce looopback0 scope 10

R3: ip pim send-rp-announce looopback0 scope 10

R2: ip pim send-rp-discovery looopback0 scope 10

In this case, the RP candidates are R1 & R3, and each is advertising itself
as RP for all multicast group addresses (224.0.0.0/4). R2 is the mapping
agent, and when it gets RP announcements from the two candidates, it will
chose R3 as RP due to its higher IP address and advertise this to all pim
routers. Should R3 fail, the mapping agent will then chose R1 and advertise
this to all pim routers. R1 is therefore a backup RP.

Example2-BSR

R1: ip pim rp-candidate lo0 priority 10

R3: ip pim rp-candidate lo0 priority 30

R2: ip pim bsr-candidate lo0

In this case, R2 the mapping agent will advertise an RP-set that includes
both candidate RPs, as well as their priority settings, for all multicast
group addresses. Each pim router will then select the candidate with higher
priority as RP. The other candidate will be a backup incase the first RP
fails.

When you use group-list keyword to specify group addresses for RP
candidates, and they happen to overlap, then this logic will apply too. If
the group-lists do not overlap, then you will not have backup RPs for those
group addresses.

HTH
Ben

On 7/18/07, kirit4144@gmail.com <kirit4144@gmail.com> wrote:
>
> Hi Team:
>
> I am new to this group and I apologize if this was discussed already.
>
> Can someone help me to understand how backup RP works? Also, sample
> configuration would be a great help to understand this concept.
>
> Thanks for your help!
>
> Kirit
>
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