Subject: Graceful-restart dynamically negotiable?

From: "Bruno Rijsman" <[email-masked]>
Date: Thu, 01 Aug 2002 15:55:26 -0400

Could we add some text to draft-ietf-idr-restart-05.txt to document
whether or not dynamic capability negotiation is supported for the
graceful-restart capability?

I vaguely remember an earlier post on this mailing list stating that
graceful-restart cannot be dynamically negotiated. If that is the
case we only need to state this in the graceful restart draft.

On the other hand, we may decide that dynamic capability negotiation
of graceful restart is useful. It allows us to turn graceful restart on
or off and it allows us the change the restart-time without needing to
bounce the session. In this case we need to add some more elaborate text
to draft-ietf-idr-restart-05.txt. Some issues to be covered in this case
include:
- Are the < AFI, SAFI > values in the graceful-restart capability in a
  capability message cumulative or not?
- What to do about the End-of-RIB marker if graceful restart is turned
  on or off in the middle of a session?

If there is enough interest in making graceful restart dynamically
negotiable I could propose some specific text.

If there is no response I will assume that dynamic capability
negotiation of is not considered useful. In this case, receiving a
capability message containing the "graceful-restart" capability message
will be considered an error and will result in a notification.

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From: "Krishnan, Vijay G." <[email-masked]>
Date: Fri, 2 Aug 2002 15:06:40 -0400

If it is a dynamic capability, its useful for planned restarts also.

regards
Vijay

-----Original Message-----
From: Wei Cao [mailto:[email-masked]]
Sent: Friday, August 02, 2002 1:20 PM
To: [email-masked]; 'Bruno Rijsman'; Abarbanel, Benjamin
Subject: Re: Graceful-restart dynamically negotiable?

 Hi, Bruno;

      I agree the dynamic capability negotiation is useful to graceful
restart
capability advertisement.  The BGP speaker advertise the graceful restart
capability is just to express its ability  to preserve its forwarding state

when it do restart. And at the end of graceful restart procedure,  its
preserved
states will be replaced by the initial updates received from all its BGP
peers,
no matter its BGP peers cooperation or not.

   So, since no harm to its peers,  terminating the peer session when BGP
speaker detect one of its peer doesn't support graceful restart is  not a
good
behavior. Unnecessary withdrawn routes cause the routing flap and
affect the internet.

   Dynamic advertising the graceful restart capability without broken the
peering session can prevent this problem since the decision is done by
receiver side: ignore or accept.

    Regards;

  -- wei

"Abarbanel, Benjamin" wrote:

> My 1.99 cents worth:
>
> If the implementation can configure the Graceful-restart mechanism
> dynamically
> (after the peering session is up), they I would expect the dynamic
> capability negotiation to be able to negotiate the graceful-restart
> capability dynamically
> without causing a session reset.
>
> Ben
>
> > -----Original Message-----
> > From: Bruno Rijsman [mailto:[email-masked]]
> > Sent: Thursday, August 01, 2002 3:55 PM
> > To: [email-masked]
> > Subject: Graceful-restart dynamically negotiable?
> >
> >