Subject: RE : [Idr] draft-dubois-bgp-planned-maintenance-00.txt

From: "DUBOIS Nicolas FTRD/DAC/ISS" <[email-masked]>
Date: Wed, 7 Jul 2004 19:24:19 +0200

Hi Robert,

Thanks for your review and comments.

Comments in line,
Regards,

Nicolas, Bruno, Benoit

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]] On
> Behalf Of Robert Raszuk
> Sent: Tuesday, July 06, 2004 11:52 PM
> To: DUBOIS Nicolas FTRD/DAC/ISS
> Cc: [email-masked]
> Subject: Re: [Idr] draft-dubois-bgp-planned-maintenance-00.txt
> 
> 
> Hi Nicolas,
> 
> Would it be possible to either add a section to your draft or
> at least 
> discuss on the list why existing BGP attributes if properly 
> used can't 
> achieve the same goal of graceful shutdown of the BGP peer ?
> Since your proposal already calls for full table churn I am 
> not sure if 
> using any existing tools would not help. Depending on the 
> e/iBGP cases a 
> router can effectively discourage peers from using his paths 
> simply by 
> injecting right values of MED, local preference or cost 
> community with 
> pre-best path POI.

ND: Using existing attributes may be possible. But it's hard to know
for a router, which BGP selection rule is beeing used by its peers and
must be hit. As you said, it could be MED, local preference, dedicated
community, IGP cost...

ND: BGP withdraw have the following advantages:
- the size of the message (shorter than new BGP updates)
- independent of the BGP selection rules and policies used in peers
routers.
- same behavior for iBGP and eBGP sessions 
- No or very little modification of the existing BGP mechanisms

ND: As written in the draft, these BGP withdraw could already be
generated
by a local policies filtering out all advertised routes. But using a
local
BGP policy would require changing the configuration each time and could
generate errors.

ND: We'll add a section in the draft to discuss your remarks.

> Also I could have missed it but where is the boundary of your 
> graceful 
> shutdown ? Is this always only peer to peer (1:N) ?

ND: I'm not sure I understand correctly your question.
ND: This is a per BGP session (or per AFI/SAFI) mechanism. From the
peers
point of view, there is no change to the BGP behavior. An eBGP peer or a
BGP RR
will probably reflect the changes to their BGP sessions.
 
> Rgs,
> R.
> 
> 
>  > DUBOIS Nicolas FTRD/DAC/ISS wrote:
>  >
> > Hi,
> > 
> > We would appreciate your feedback.
> > 
> > Thanks
> > 
> > Nicolas, Bruno, Benoit
> > 
> > 
> > A New Internet-Draft is available from the on-line Internet-Drafts 
> > directories.
> > 
> > 
> > 	Title		: Graceful Shutdown of BGP Sessions
> > 	Author(s)	: N. Dubois, et al.
> > 	Filename	: draft-dubois-bgp-planned-maintenance-00.txt
> > 	Pages		: 8
> > 	Date		: 2004-6-30
> > 	
> > To ease the maintenance of BGP-4 sessions and limit the amount of 
> >    traffic that is lost during planned maintenance on routers, a 
> >    specific mechanism is proposed in order to gracefully shutdown a 
> >    router or a session. 
> >    It's proposed that a router first withdraw its route to its peer 
> >    to initiate their convergence. After a timer the router 
> can proceed 
> >    with the closing of the BGP sessions and consequently remove its 
> >    peers'routes from it's RIB (Routing Information Base).
> > 
> > A URL for this Internet-Draft is: 
> > 
> http://www.ietf.org/internet-drafts/draft-dubois-bgp-planned-maintenan
> > ce
> > -00.txt
> > 
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