Subject: [pim] Default BSR priority issue!

From: Prashant Jhingran <[email-masked]>
Date: Wed, 03 Nov 2004 12:12:26 +0800

Hi All,

The latest BSR draft no where mentions about the default BSR priority &
that's why probably few
Developers/vendors are using the value "Zero" as default BSR priority.

The problem comes when the EBSR is getting shutdown. 

There are no means by which the current EBSR can inform the other
routers in the domain about itself going down.
(Since default BSR priority and the priority to inform when BSR goes
down boils down to the same numerical value i.e. Zero).

I think this issue is more important than the RP-mapping we are
discussion currently and this problem should be resolved in the coming
BSR draft....this would also lead to faster convergence during graceful
EBSR shutdown scenarios.

As per draft-ietf-pim-sm-bsr-04.txt, the latest BSR draft....
======================================================================
4.1.  Bootstrap Message Format....
"BSR priority
     Contains the BSR priority value of the included BSR.  This field is
     considered as a high order byte when comparing BSR addresses.  Note
     that for historical reasons, the highest BSR priority priority is
     255 (the higher the better), whereas the highest RP Priority (see
     below) is 0 (the lower the better)."

And 

3.2.  Creating the RP-Set at the BSR....
"When an elected BSR is being shut down, it should immediately originate
a Bootstrap message listing its current RP-Set, but with the BSR
priority field set to the lowest priority value possible.  This will
cause the election of a new BSR to happen more quickly."
========================================================================
=

Regards,
Prashant Jhingran

Huawei Technologies 
Beijing, China
Ph# 00-86-10-82882837  (O)  
        00-86-10-62983443  (R)
www.huawei.com

"You see, all the problems in the world are created by those who want
'perfection.' "
   -- Sri Sri Ravi Shankar  www.artofliving.org  

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From: Nidhi Bhaskar <[email-masked]>
Date: Tue, 2 Nov 2004 20:49:28 -0800 (PST)

> BSR draft....this would also lead to faster convergence during graceful

Yes, we could have better defaults, but this problem is fairly simple
to fix via appropriate configuration (unlike the RP-mapping issue
being discussed). So don't agree on the importance ranking :).

That said, I am open to putting in a better default in the spec. Will
include this in the longish todolist we have for this document...

Thanks,
Nidhi.