Thanks for the useful feedback. --Bruno
> -----Original Message----- > From: Ben Maddison [mailto:b...@workonline.co.za] > Sent: Wednesday, March 15, 2017 4:23 PM > To: Job Snijders; DECRAENE Bruno IMT/OLN > Cc: grow@ietf.org > Subject: RE: [GROW] draft-ietf-grow-bgp-gshut status? > > I would be very happy with that outcome. > We've been using this for ages, and would like to see it work more widely in > our adjacent > networks. > > Although not truly a fix for the transitivity problem, when we match on > gshut from a peer, in > addition to setting a lower-than-usual LP, we also append no-export, which > prevents gshut- > ed prefixes from leaking at all. > I've never been hugely worried about the security consequences otherwise. > > Cheers, > > Ben Maddison > > Director > Workonline Communications (Pty) Ltd > > Office: +27 (0) 21 200 9000 > Mobile: +27 (0) 82 415 5545 > Email: b...@workonline.co.za > SIP: b...@workonline.co.za > > > > > -----Original Message----- > From: GROW [mailto:grow-boun...@ietf.org] On Behalf Of Job Snijders > Sent: Wednesday, March 15, 2017 4:54 PM > To: bruno.decra...@orange.com > Cc: grow@ietf.org > Subject: Re: [GROW] draft-ietf-grow-bgp-gshut status? > > Hi Bruno, > > On Wed, Mar 15, 2017 at 02:00:37PM +0000, bruno.decra...@orange.com wrote: > > > From: GROW [mailto:grow-boun...@ietf.org] On Behalf Of Job Snijders > > > > Sent: Wednesday, March 15, 2017 2:11 PM > > > > > > I noticed that > > > https://tools.ietf.org/html/draft-ietf-grow-bgp-gshut-06 > > > expired two years ago. Can anyone offer some insight why it lapsed? > > > > In order to signal the graceful shutdown over the EBGP session, gshut > > uses a "well-know" BGP community. Compared to using a protocol > > extension, this allows a vanillia sender/receiver to handle the > > information using a regular BGP policy. > > So far so good. This is specified, implemented both with BGP policy > > and automated by some routers, tested (both options). > > > > Now, for some deployments, the use of a non-transitive community offer > > a better assurance that the community has indeed be originated by the > > connected eBGP peer. The issue is that currently there is no > > implementation of non-transitive well-known communities. > > draft-ietf-idr-reserved-extended-communities is a short draft to > > define non-transitive well-known communities. It proposed to re-use an > > "existing" non-transitive extended community, defined for four-octets > > AS: draft-ietf-idr-as4octet-extcomm-generic-subtype. But it turns out > > that this latter draft did not progress and has recently been replaced > > by BGP large community. The later do no support non-transitive > > community. > > > > So after waiting for some years for > > draft-ietf-idr-as4octet-extcomm-generic-subtype, this path has just > > been closed. As of today, the possible options seems: > > > > - forget about non-transitive community. In particular as during the > > BGP large community discussions, the requirement for non-transitive > > community has been discussed and explicitly called as not needed. So > > let's listen to this and do the same. > > I'd like to add a small nuance: For the use case of large communities, > non-transitivity was > considered an undesirable property. > > To be honest, if the 'gshut' community 'escapes' the adjacent ASN for which > it was intended, > what is the worst that can happen? That BGP speakers somewhere in the DFZ > consider the > path less desirable? This aligns with what is expected to happen in the near > future anyway: > the bgp session will be torn down and the path will cease to exist. > > In the case where no shutdown event follows (the gshut community is used as > a traffic > engineering trick), it kind of goes in the same category as intermediat > networks prepending > ASNs to the AS_PATH to make it less desirable, or fiddling with origin. If I > were to consider > "permanent use" of the gshut community a violation of my agreement with the > adjacent > network, this would be easy enough to monitor for and subsequently resolve > at layer-8. > > > - have draft-ietf-idr-reserved-extended-communities use a different > > extended community type. This is easy to write, but if this does not > > get implemented, the value is limited/null. > > I concur. A similar consideration could be made whether gshut deserves its > own path > attribute or not. Usually the nice thing about well known rfc 1997 > communities is their > rapid implementation and deployability. > > > > What implementatations exist? A fellow operator told me that IOS, > > > IOS XE has support for graceful shutdown, are there others? > > > > Same information on my side. With the restriction that those > > implementations only implement the transitive community. > > ack. > > I'm somewhat inclined to proceed with the gshut concept as a well-known > transitive rfc > 1997 community. What do others think? > > Kind regards, > > Job > > _______________________________________________ > GROW mailing list > GROW@ietf.org > https://www.ietf.org/mailman/listinfo/grow _________________________________________________________________________________________________________________________ Ce message et ses pieces jointes peuvent contenir des informations confidentielles ou privilegiees et ne doivent donc pas etre diffuses, exploites ou copies sans autorisation. 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