Re: [pim] PIM graceful restart (non-stop forwarding) capability

"janardhan kulkarni" <janardhan.kulkarni@gmail.com> Wed, 22 August 2007 07:12 UTC

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Date: Wed, 22 Aug 2007 12:42:37 +0530
From: janardhan kulkarni <janardhan.kulkarni@gmail.com>
To: Srikanth Rao <srikanth@force10networks.com>
Subject: Re: [pim] PIM graceful restart (non-stop forwarding) capability
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Yes, as of now if does not have GR mechanism. The genid feature does
enable us to recreate the "most" of state machine quickly, it does not
gives rules for NON_STOP forwarding.

Also, GENID itself does not ensure proper rebuilding of the
state-machine completely.
It also does not ensure NLT does not expire , Joins do get timed out
(although it is rare) and it does not take into account the assert
state machine.

I had raised this concern some time back, and I think there is a need
to analyse this issue.

Thanks.

On 8/22/07, Srikanth Rao <srikanth@force10networks.com> wrote:
>
>
>
>
> Hi,
>
>
>
> How do PIM routers know about the graceful-restart capability of their
> peers? In BGP, OSPF and other protocols, this capability is advertised
> upfront when the adjacencies are formed. So that when their neighbor
> liveliness is lost, they hold on to the routes to support the non stop
> forwarding of traffic.
>
>
>
> In PIM, a new GenID in the Hello message indicates that the router
> restarted. But that doesn't necessarily mean that router is capable of doing
> non stop forwarding. So, in other words, when a PIM speaker detects that its
> neighbor has gone down (or restarting), what is the criterion on which it
> holds on to the updates from its neighbor in non-stop forwarding mode? Is
> there any standardized option or mechanism for this? If this has been
> already discussed, can someone point me to the discussion?
>
>
>
> Thanks
>
> Srikanth
>
>
>
>
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-- 
Bye,
Janardhan.
"I have never been hurt by what I have not said."
  -Calvin Coolidge

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