From: ccie2be (ccie2be@nyc.rr.com)
Date: Fri Nov 07 2003 - 11:25:17 GMT-3
RE: PIMv2 BSR questionBSR uses a hop-by-hop flooding of special BSR messages
to elect the BSR. These messages are received by all routers in the network.
These BSR messages are flooded, by default, every 60 seconds. The candidate
BSR with the highest priority is elected the BSR. In the case of a tie, the
one with the highest IP address becomes the BSR.
Since these messages reach all the PIM routers in the network, they will, of
course, also reach all the candidate RP's. Once the candidate RP's know where
the BSR router is, they (the candidate RP's) will send via unicast their
group-to-RP mappings to the elected BSR. The BSR then floods these mappings
to all PIM routers in the network. If more than 1 RP contains a mapping for
the same group, the routers receiving these mappings will have a choice of
RP's for a that group and will choose the RP based on a hashing algorithm.
Note that for this flooding mechanism to work properly all the routers must be
configured with multicast enabled.
HTH, dt
----- Original Message -----
From: Pun, Alec CL
To: ccie2be ; gs (E-mail)
Sent: Friday, November 07, 2003 8:45 AM
Subject: RE: PIMv2 BSR question
Thanks.
One more question, how does the other non-RP PIM routers learn of the
RP-to-group mapping ? Do they listen to a multicast group just like auto-RP
does ? Your given link seems does not cover it about.
regards,
alec
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Friday, November 07, 2003 9:28 PM
To: Pun, Alec CL; gs (E-mail)
Subject: Re: PIMv2 BSR question
Hi Alec,
The concept behind BSR is essentially the same as Auto-RP. The
candidate-RP's inform the BSR of the group-to-mapping and then the BSR tells
all the other routers. One difference is that a BSR is elected from the
group of potential BSR's.
There are some very good resources that go into detail about this. See
http://www.cisco.com/univercd/cc/td/doc/cisintwk/intsolns/mcst_sol/rps.htm
Also, see
http://www.cisco.com/warp/public/732/Tech/multicast/multicast_techdoc.shtml
In addition, Doyle's Routing TCP/IP vol II and Willianson's book, Developing
IP Multicast Networks provide excellent, comprehensive information on these
topics.
HTH, dt
----- Original Message -----
From: "Pun, Alec CL" <Alec.CL.Pun@pccw.com>
To: "gs (E-mail)" <ccielab@groupstudy.com>
Sent: Friday, November 07, 2003 5:02 AM
Subject: PIMv2 BSR question
> After reading through the IP Multicast section in the DocCD, still
confused
> by the concept of PIMv2 BSR.
>
> I assume BSR is serving similar purpose as Cisco Auto-RP, but what's the
use
> of specifying candidate RP ? Does it follow similar concept of Auto-RP
> mapping agent and RP which always double itself ?
>
> thanks
> alec
>
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