Re: [Lsr] draft-ietf-lsr-isis-rfc5306bis-01

"Les Ginsberg (ginsberg)" <ginsberg@cisco.com> Fri, 24 May 2019 21:21 UTC

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From: "Les Ginsberg (ginsberg)" <ginsberg@cisco.com>
To: Uma Chunduri <umac.ietf@gmail.com>, "lsr@ietf.org" <lsr@ietf.org>
Thread-Topic: [Lsr] draft-ietf-lsr-isis-rfc5306bis-01
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Date: Fri, 24 May 2019 21:21:30 +0000
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Subject: Re: [Lsr] draft-ietf-lsr-isis-rfc5306bis-01
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Uma –

Inline.

From: Lsr <lsr-bounces@ietf.org> On Behalf Of Uma Chunduri
Sent: Friday, May 24, 2019 10:49 AM
To: lsr@ietf.org
Subject: [Lsr] draft-ietf-lsr-isis-rfc5306bis-01

As asked by chairs I was trying to write the shepherd report on this doc.

Have few quick questions on this work:

1.

Observation: The new text added in 2.2.3 (PR and PA bits) is almost similar  to section 2.2.1 (RR and RA bits)

Now is there any relation of the timer here with T3 (which would have been set by restarting router with the value received with RA bit set, assuming it is lower than the initialized value  65535).

There is no description or guidance on how these values are related and how the restarting router handle this.

[Les:] The timers (T1, T2, T3) are NOT relevant to PR/PA.
PR is sent BEFORE a router does a restart to alert the neighbors that the signaling router’s control plane is going away for a time.

RR/RA are associated with what happens AFTER the router has restarted and now wants to reacquire adjacencies/LSDB.

I do not know what text in the draft suggests to you that there is any relation between PR/PA and RR/RA.

2.

On the text below

"a.  If additional topology changes occur, the adjacency which is in
       planned restart state MAY be brought down even though the hold
       time has not yet expired.  Given that the neighbor which has
       signaled a planned restart is not expected to update its
       forwarding plane in response to signaling of the topology changes
       (since it is restarting) traffic which transits that node is at
       risk of being improperly forwarded. "

Is this any topology change ? Not related to the restarting router in question?

Need clarification text here or point me if I miss something.


[Les:] What constitutes a topology change significant enough to trigger bringing down the adjacency is an implementation decision.
Definition of the conditions is NOT an interoperability issue and therefore does not fall within the scope of the draft.

   Les


Have few more questions/comments overall and shall come back.

--
Uma C..