Subject: RE: [Fwd: I-D ACTION:draft-pan-rsvp-te-restart-01.txt]

From: "David Allan" <[email-masked]>
Date: Wed, 15 Aug 2001 10:19:18 -0400

Ping:

I'm having trouble correlating route flap instability data with your problem
statement. Similarly I have trouble with the analogy between graceful
restart for routing (which has a fair chasm between it and forwarding) and a
soft state signalling protocol which would appear to require a much tighter
coupling.

Is this really more applicable to GMPLS and should be tagged as such?

rgds
Dave

-----Original Message-----
From: Ping Pan [mailto:[email-masked]]
Sent: Wednesday, August 15, 2001 9:34 AM
To: [email-masked]
Cc: [email-masked]
Subject: Re: [Fwd: I-D ACTION:draft-pan-rsvp-te-restart-01.txt]

[email-masked] wrote:
> 
> Ping,
> 
> Can you please explain (i) what causes such RSVP nodal re-starts in the
1st
> place 

Neil,

The same cause why routing engine may fail in the network, while data
forwarding is fine. The graceful restart technique is not new, as being
define for IGP and BGP already.

> and (ii) how frequently you see them per reason (I assume they must be
> of some concern to have written this ID)?
>

If you believe the data collected at
http://www.merit.edu/ipma/instability/, network does run into instable
conditions. Our draft is to localize the problem when that happens.

- Ping

---

From: Ping Pan <[email-masked]>
Date: Wed, 15 Aug 2001 07:33:02 -0700

> David Allan wrote:
> 
> Ping:
> 
> I'm having trouble correlating route flap instability data with your
> problem statement. Similarly I have trouble with the analogy between
> graceful restart for routing (which has a fair chasm between it and
> forwarding) and a soft state signalling protocol which would appear to
> require a much tighter coupling.
> 

Dave,

The point was that in the network, there could be cases where the
control engine is crashed while the data forwarding engine is fine. To
reduce the side-effects, control protocols (routing and signaling)
should use various graceful restart mechanisms. In our draft, I think
the control and forwarding are tightly coupled. Please let me know why
you think otherwise.

> Is this really more applicable to GMPLS and should be tagged as such?

Both GMPLS and MPLS can benefit from this. In case of GMPLS, graceful
restart can be used to recover from control channel failure.

Regards,

- Ping

---

From: Peter Willis <[email-masked]>
Date: Wed, 15 Aug 2001 18:19:29 +0100

Ping & The List,

Has any one observed the loss of RSVP state due simply to RSVP packet losses? 
It would seem that RSVP-TE graceful restart could aid recovery from this
situation?  Or do people expect rfc2961 to protect against problems with small
Rs & Ks?

Regards,
Peter.

---

From: Ping Pan <[email-masked]>
Date: Wed, 15 Aug 2001 10:48:22 -0700

> situation?  Or do people expect rfc2961 to protect against problems with small

RFC2961 defines exponential backoff to improve reliable delivery. People 
can increase K also.

- Ping

---

From: Ray Qiu <[email-masked]>
Date: Wed, 15 Aug 2001 11:42:07 -0700 (PDT)

Ping,

I have one simple question regarding the RSVP restart-01 draft.

How can you demonstrate the control plane failure?

Thanks,
Ray