Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-link-overload-01
"Acee Lindem (acee)" <acee@cisco.com> Fri, 09 October 2015 11:23 UTC
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From: "Acee Lindem (acee)" <acee@cisco.com>
To: Shraddha Hegde <shraddha@juniper.net>, Pushpasis Sarkar <psarkar@juniper.net>
Thread-Topic: OSPF Link Overload - draft-hegde-ospf-link-overload-01
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Date: Fri, 09 Oct 2015 11:23:47 +0000
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Cc: Hannes Gredler <hannes@gredler.at>, OSPF WG List <ospf@ietf.org>, Mohan Nanduri <mnanduri@microsoft.com>, "Jalil, Luay" <luay.jalil@verizon.com>
Subject: Re: [OSPF] OSPF Link Overload - draft-hegde-ospf-link-overload-01
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Hi Shraddha, On 10/8/15, 11:55 PM, "Shraddha Hegde" <shraddha@juniper.net> wrote: >Acee, > >The Link overload sub TLV would go in extended link TLV since the use >case is applicable to TE as well as non- TE deployments. >The metric change on the reverse side applies to TE TLV as well as >ROUTER LSA. > IGP metric set to 0xffff and TE metric set to oxfffffffe. >This wasn't very clear in the -01 version of the draft. Will submit the >-02 version very soon. Please resubmit as a WG document (draft-ietf-ospf-link-overload-00.txt) - there has been a lot of interest in this function and the details. Thanks, Acee > >Rgds >Shraddha > >-----Original Message----- >From: Acee Lindem (acee) [mailto:acee@cisco.com] >Sent: Friday, October 09, 2015 2:37 AM >To: Shraddha Hegde <shraddha@juniper.net>; Pushpasis Sarkar ><psarkar@juniper.net> >Cc: OSPF WG List <ospf@ietf.org>; Hannes Gredler <hannes@gredler.at>; >Mohan Nanduri <mnanduri@microsoft.com>; Jalil, Luay ><luay.jalil@verizon.com> >Subject: Re: OSPF Link Overload - draft-hegde-ospf-link-overload-01 > >Hi Shraddha, >If this is truly TE, why would you use the OSPF prefix/link attribute >instead of the actual TE metric specified in RFC 3630? >Thanks, >Acee > > >On 9/29/15, 1:05 PM, "Shraddha Hegde" <shraddha@juniper.net> wrote: > >>Acee, >> >>I am not sure if I am able to convey what I mean by the "controller use >>case" in the previous mail thread. Here is another attempt to explain the >>use case. >> >>With metric change there is no guarantee that LSP will move to a >>different path. If the current path satisfies all constraints of the LSP >>and there is no better path >>Satisfying the constraints then the LSP would remain up and very much on >>the link that is going to be replaced. I mentioned in another mail >>thread, the high metric is >>Usable metric and does not mean "link down". >> >>Link maintenance is a special scenario. The LSP MUST move out of the >>link. Controller can take special actions if it knows the link is in >>overload state >>For Ex: Relax certain constraints of the LSP for the duration of >>maintenance and move the LSP on a different path. >>All these activities should happen in a non- disruptive fashion for the >>service and that’s the reason the link metric cannot be changed to >>max-metric (0xffffffff) >> >>If the "link overload" information remains at the link level, controller >>needs to take action based on metric alone. >>It might work for most cases assuming there are better alternate paths >>satisfying same constraints but we cannot guarantee >>LSPs will move from the link in all cases. If we consider a case when >>multiple links in the network go for maintenance/replacement >>simultaneously >>then there is higher probability that alternate paths satisfying the >>constraints can't be found and controller needs to perform special >>actions to >>move the LSPs around. >> >>IMHO, "link overload" is a characteristic of the link just like color, >>bandwidth etc and it makes sense to flood it area wide just like other >>attributes of the link. >> >>Rgds >>Shraddha >> >>-----Original Message----- >>From: Pushpasis Sarkar >>Sent: Tuesday, September 29, 2015 8:27 PM >>To: Acee Lindem (acee) <acee@cisco.com> >>Cc: Shraddha Hegde <shraddha@juniper.net>; OSPF WG List <ospf@ietf.org>; >>Hannes Gredler <hannes@gredler.at>; Mohan Nanduri >><mnanduri@microsoft.com>; Jalil, Luay <luay.jalil@verizon.com> >>Subject: Re: OSPF Link Overload - draft-hegde-ospf-link-overload-01 >> >>Hi Acee, >> >> >> >> >>On 9/29/15, 8:15 PM, "Acee Lindem (acee)" <acee@cisco.com> wrote: >> >> >>>I apologize if I offended you. I just wanted to avoid the circular >>>discussions and repetition of information having no bearing on the >>>issues raised. >>[Pushpasis] No no. You have not offended me in any ways. So we are good >>then. I was worried that I might have offended you instead. :) >>> >>> >>>> [Pushpasis] Like mentioned already, and again in my opinion, this will >>>>help the controller deal with scenarios where it needs to distinguish >>>>between situations in which a link has been administratively put into >>>>‘out-of-order’ from situations where the link has degraded to a >>>>‘malfunctioning’ state and needs attention. Unfortunately I cannot come >>>>up with a use-cases how this distinction can be used (other than >>>>diverting service traffics away from the links). Perhaps some of the >>>>operators may throw more light. >>> >>>I’d like to hear from the operators (especially the authors Luay and >>>Mohan). >>[Pushpasis] Me too :) >>> >>> >>>> >>>> >>>> Hoping I have not failed to communicate once more. If you still feel >>>>so, please let me know. And I will refrain myself from answering on >>>>this thread further. >>> >>>I think we are communicating now - the main question is what does this >>>link-maintenance condition needs to be flooded throughout the OSPF >>>routing domain when it seems that link-local signaling would offer a >>>much more straight-forward solution. The response so far has been, “For >>>the controller use-case” without any explanation of why increasing the >>>forward and reverse metrics isn’t enough (especially since you are doing >>>this anyway for backward compatibility). Les Ginsberg raised the same >>>point. >>[Pushpasis] I will not further exaggerate my already-expressed reasoning >>as I do not have a definite use case in hand. Hoping some operators in >>the working group may have more solid use-cases for this. >> >>Thanks and Regards, >>-Pushpasis >> >>> >>>Thanks, >>>Acee >
- [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)