Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-link-overload-01
Manav Bhatia <manavbhatia@gmail.com> Wed, 30 September 2015 14:02 UTC
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Date: Wed, 30 Sep 2015 19:32:24 +0530
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From: Manav Bhatia <manavbhatia@gmail.com>
To: Shraddha Hegde <shraddha@juniper.net>
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Cc: Hannes Gredler <hannes@gredler.at>, OSPF WG List <ospf@ietf.org>, "Jalil, Luay" <luay.jalil@verizon.com>, Mohan Nanduri <mnanduri@microsoft.com>
Subject: Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-link-overload-01
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Hi, I am probably joining the party quite late, so apologies in advance if the following has already been discussed and discarded. Why cant the following be done: Set the metric of all transit links/connections on an “overloaded” router to 0xffff in its Router LSAs. This will result this router to not be included as a transit node in its neighbors SPF tree. Stub links can still be advertised with their normal metrics so that they are reachable even when a router is “overloaded”. This way you can mimic IS-IS OL bit. Cheers, Manav On Mon, Sep 28, 2015 at 10:43 AM, Shraddha Hegde <shraddha@juniper.net> wrote: > Acee, > > Thanks for picking up the draft for adoption. > > I believe this draft is very useful in automating the link upgrade process > and software upgrade process in overlay deployments and > hence support WG adoption as co-author. > > I would like to take this opportunity to discuss few of the points > raised during Prague meeting. > > 1. Whether to keep the "Link overload" advertisement at area level or at > link level. > > In controller based deployments, it's useful to advertise the impending > maintenance of the link to the controller so that controller can take > Special actions based on the information. The use case is described in sec > 5.2 in the draft. > The draft advocates increasing the metric to usable high metric on both > ends of the link. This is for backwards compatibility and to avoid need of > flag > Day upgrade on all nodes. > > Controller cannot assign special meaning to the metric for ex: Metric > XXXX means the link going for maintenance and take different actions based > on metric. > > For a completely automated upgrade process, controller would need a fine > grained and specific information that the link is going for maintenance so > that the services that use the particular link find a different path > forcefully while keeping the entire process non-disruptive. > > > 2. Use of high metric on either side of the link to divert the traffic. > > As I already mentioned before, draft advocates raising the reverse metric > to a high metric but that is for backwards compatibility and to avoid > Need for flag-day upgrade. There were suggestions at the Prague meeting to > use lower bandwidth advertisements as well as removal of > Link characteristics to force the services on different path. These > mechanisms would be disruptive and defeats the purpose of the draft. > > 3. Backward compatibility > > "Link-overload" is a new information attached to a link and is very > similar to a new constraint being added to the link. > This information is non-invasive in the sense that services that do not > want to look at the new constraint (link overload) > May depend only on the metric to take specific actions. > > Whereas services that have specialized requirement of providing > non-disruptive upgrades can do so by processing the new constraint. > > Section 4 in the draft talks about backwards compatibility. > I'll add more clarifications in the coming days. > > Rgds > Shraddha > > > -----Original Message----- > From: OSPF [mailto:ospf-bounces@ietf.org] On Behalf Of Acee Lindem (acee) > Sent: Saturday, September 26, 2015 6:05 AM > To: OSPF WG List <ospf@ietf.org> > Subject: [OSPF] OSPF Link Overload - draft-hegde-ospf-link-overload-01 > > In Prague, there was consensus in the room that this use case was not > covered by existing mechanisms and that it was a problem the WG should > solve. There were differing opinions as to the exact solution but that > should not preclude OSPF WG adoption. > > Please indicate your support (or concerns) for adopting this as a WG > Document. > > > Thanks, > Acee > > > _______________________________________________ > OSPF mailing list > OSPF@ietf.org > https://www.ietf.org/mailman/listinfo/ospf > > _______________________________________________ > OSPF mailing list > OSPF@ietf.org > https://www.ietf.org/mailman/listinfo/ospf >
- [OSPF] OSPF Link Overload - draft-hegde-ospf-link… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Les Ginsberg (ginsberg)
- [OSPF] FW: OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] FW: OSPF Link Overload - draft-hegde-o… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Ahmed Bashandy (bashandy)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Les Ginsberg (ginsberg)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Les Ginsberg (ginsberg)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Anil Kumar S N (VRP Network BL)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Uma Chunduri
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Pushpasis Sarkar
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Manav Bhatia
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Anil Kumar S N (VRP Network BL)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Shraddha Hegde
- Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-… Acee Lindem (acee)