Re: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt
"Acee Lindem (acee)" <acee@cisco.com> Thu, 27 July 2017 21:59 UTC
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From: "Acee Lindem (acee)" <acee@cisco.com>
To: "Acee Lindem (acee)" <acee@cisco.com>, Shraddha Hegde <shraddha@juniper.net>, "Peter Psenak (ppsenak)" <ppsenak@cisco.com>, "Ketan Talaulikar (ketant)" <ketant@cisco.com>
CC: "ospf@ietf.org" <ospf@ietf.org>
Thread-Topic: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt
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Date: Thu, 27 Jul 2017 21:58:58 +0000
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Subject: Re: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt
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On 7/27/17, 5:49 PM, "OSPF on behalf of Acee Lindem (acee)" <ospf-bounces@ietf.org on behalf of acee@cisco.com> wrote: >Hi Shraddha, Co-authors, > >I just read the draft and I there shouldn’t be any more contention. >However, I have a couple questions on the use cases. > > 1. In the pseudowire use case (7.1), I don’t understand where OSPF >link-overload is being advertised. I guess the assumption is that the >pseudowires are running OSPF? Also, the use case references a private VLAN >with 3 CEs. However, I see pseudowires as P2P. I guess VPLS is also characterized as a pseudowire service. Thanks, Acee > > 2. In the OSPF L3VPN use case, mention that the CEs are dual-homed. This >include in my editorial comments. > > 3. In the Hub-and-Spoke use case (7.4), why wouldn’t one just use RFC >6987 rather than advertising link-overload for all the links? > >I’ll send my editorial comments offline. > >Thanks, >Acee > > > >On 7/27/17, 6:03 AM, "Shraddha Hegde" <shraddha@juniper.net> wrote: > >>Acee/OSPF WG, >> >>I just realized my post on updated draft for -08 version posted on 17-07 >>was stuck at confirmation stage. >> >>I think it's useful to have normative language to ensure >>interoperability. I have updated the "elements of procedure" >>Section accordingly. Please review the -08 version. >> >>Thanks >>Shraddha >> >>-----Original Message----- >>From: Acee Lindem (acee) [mailto:acee@cisco.com] >>Sent: Tuesday, July 25, 2017 3:59 AM >>To: Shraddha Hegde <shraddha@juniper.net>; Peter Psenak (ppsenak) >><ppsenak@cisco.com>; Ketan Talaulikar (ketant) <ketant@cisco.com> >>Cc: ospf@ietf.org >>Subject: Re: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt >> >>Hi Shraddha, >> >>Great - I think we are all in sync. >> >>What are your thoughts on using “MUST” for the setting the link metrics >>in sections 5.1, 5.2, 5.3 and 5.5? I checked RFC 6987 (and RFC 3137) and >>they don't use normative language since setting the link-metrics to >>0xffff is the very definition of OSPF stub router behavior. >> >>Also, one more reference to RFC 4203. >> >>*** 438,445 **** >> field in the Extended Link TLV carries the Local interface-id >>instead >> of the IP address. The Local/Remote Interface ID sub-TLV MUST be >> originated when there are multiple parallel unnumbered interfaces >>! between two nodes. Procedures to obtain interface-id of the remote >>! side are defined in [RFC4203]. >> >> >> >>--- 438,445 ---- >> field in the Extended Link TLV carries the Local interface-id >>instead >> of the IP address. The Local/Remote Interface ID sub-TLV MUST be >> originated when there are multiple parallel unnumbered interfaces >>! between two nodes. One of the mechanisms to obtain remote >>! interface-id is described in [RFC4203]. >> >> >> >>Thanks, >>Acee >> >> >>On 7/10/17, 12:52 AM, "Shraddha Hegde" <shraddha@juniper.net> wrote: >> >>>All, >>> >>>Link-local flooding was added as an optimization for use-cases that do >>>not need area level flooding on request from Acee. >>>I agree flooding area level in all cases is a reasonable way forward as >>>the overhead isn't much. >>> >>>If anyone has objections to removing Link-local scope advertisement, do >>>let me know. >>> >>>Rgds >>>Shraddha >>> >>> >>>-----Original Message----- >>>From: Acee Lindem (acee) [mailto:acee@cisco.com] >>>Sent: Thursday, July 6, 2017 2:55 PM >>>To: Peter Psenak (ppsenak) <ppsenak@cisco.com>; Ketan Talaulikar >>>(ketant) <ketant@cisco.com>; Shraddha Hegde <shraddha@juniper.net> >>>Cc: ospf@ietf.org >>>Subject: Re: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt >>> >>>Hi Peter, Shradha, >>> >>>On 7/6/17, 3:30 AM, "OSPF on behalf of Peter Psenak (ppsenak)" >>><ospf-bounces@ietf.org on behalf of ppsenak@cisco.com> wrote: >>> >>>>On 06/07/17 05:50 , Ketan Talaulikar (ketant) wrote: >>>>> Hi Shraddha, >>>>> >>>>> Thanks for taking care of some of the comments shared previously. >>>>>Please find below some more that were probably missed or not taken >>>>>care of. >>>>> >>>>> 1) I see that the use of link-local scope RI LSA has still been >>>>>retained in this version and not sure why. RI LSA is for node >>>>>attributes and it's use for signalling of link is not right IMO. Why >>>>>not use the link-local scope Extended Link LSA instead? >>>> >>>>an alternative would be to always flood area scope Extended Link LSA. >>>>It should not harm anything and could be used by other routers in area >>>>as a "heads-up" that remote link is becoming overloaded. >>> >>>I think this would be a good way forward as the OSPF Extended Attribute >>>LSA will most likely be advertised for SR in OSPF Service Provider >>>domains anyway. So, just advertising the area-scope for all use cases >>>would seem to be the simplify this approach and get us past this >>>discussion. In fact, the -00 version of the draft had area-scope alone >>>and I, regretfully, had suggested the OSPF RI as possible way to get >>>support either scope. >>> >>>Thanks, >>>Acee >>> >>>> >>>> >>>>> >>>>> 2) Sec 5.1, why is advertising of MAX-METRIC for the link to be >>>>>overloaded a SHOULD and not a MUST? Isn't this mandatory to ensure >>>>>backward compatibility? What if the router on which overload is >>>>>signalled does not do MAX-METRIC but the implementation on the remote >>>>>side end up doing MAX-METRIC. Would it not result in asymmetric >>>>>metric in a un-intended manner? Please consider changing all SHOULD >>>>>here to MUST to ensure backward compatibility. >>>>> >>>>> 3) Sec 5.4, can you please make similar change in language related >>>>>to the RFC4203 reference as you've done in other parts in this >>>>>version? >>>>> >>>>> Also I don't agree with the rationale you've given for not using LLS >>>>>for the link-local signalling. Even if the hello processing were >>>>>delegated to the LC, there are already a lot of protocol events which >>>>>can happen via hello packets (which includes LLS) that require >>>>>signalling update to the control plane OSPF main process. An >>>>>implementation aspect such as this should hardly be a good reason to >>>>>not use LLS for link-local signalling such as overload. >>>> >>>>+1 on the above. >>>> >>>>thanks, >>>>Peter >>>> >>>>> >>>>> Thanks, >>>>> Ketan >>>>> >>>>> -----Original Message----- >>>>> From: OSPF [mailto:ospf-bounces@ietf.org] On Behalf Of Shraddha >>>>> Hegde >>>>> Sent: 03 July 2017 11:11 >>>>> To: internet-drafts@ietf.org; i-d-announce@ietf.org >>>>> Cc: ospf@ietf.org >>>>> Subject: Re: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt >>>>> >>>>> OSPF WG, >>>>> >>>>> New version of the ospf-link-overload draft is posted. >>>>> Editorial comments received so far have been addressed in this >>>>>version. >>>>> >>>>> There was one comments to move the link-overload sub-TLV to LLS in >>>>>hello messages. >>>>> Many implementations delegate the Hello processing to >>>>>linecards/different deamons Once adjacency is established. Hello >>>>>messages are not sent to control plane post adjacency establishment. >>>>>The link-overload information typically needs to be processed after >>>>>adjacency establishment, it introduces unnecessary complexity in >>>>>hello processing. >>>>> We had a discussion among authors on this and feel advertising >>>>>link-overload sub-TLV in the LSAs is the most appropriate mechanism. >>>>> >>>>> >>>>> >>>>> Rgds >>>>> Shraddha >>>>> >>>>> -----Original Message----- >>>>> From: OSPF [mailto:ospf-bounces@ietf.org] On Behalf Of >>>>>internet-drafts@ietf.org >>>>> Sent: Monday, July 3, 2017 11:01 AM >>>>> To: i-d-announce@ietf.org >>>>> Cc: ospf@ietf.org >>>>> Subject: [OSPF] I-D Action: draft-ietf-ospf-link-overload-07.txt >>>>> >>>>> >>>>> A New Internet-Draft is available from the on-line Internet-Drafts >>>>>directories. >>>>> This draft is a work item of the Open Shortest Path First IGP of the >>>>>IETF. >>>>> >>>>> Title : OSPF Link Overload >>>>> Authors : Shraddha Hegde >>>>> Pushpasis Sarkar >>>>> Hannes Gredler >>>>> Mohan Nanduri >>>>> Luay Jalil >>>>> Filename : draft-ietf-ospf-link-overload-07.txt >>>>> Pages : 14 >>>>> Date : 2017-07-02 >>>>> >>>>> Abstract: >>>>> When a link is being prepared to be taken out of service, the >>>>>traffic >>>>> needs to be diverted from both ends of the link. Increasing the >>>>> metric to the highest metric on one side of the link is not >>>>> sufficient to divert the traffic flowing in the other direction. >>>>> >>>>> It is useful for routers in an OSPFv2 or OSPFv3 routing domain >>>>>to be >>>>> able to advertise a link being in an overload state to indicate >>>>> impending maintenance activity on the link. This information >>>>>can be >>>>> used by the network devices to re-route the traffic effectively. >>>>> >>>>> This document describes the protocol extensions to disseminate >>>>>link- >>>>> overload information in OSPFv2 and OSPFv3. >>>>> >>>>> >>>>> >>>>> The IETF datatracker status page for this draft is: >>>>> https://datatracker.ietf.org/doc/draft-ietf-ospf-link-overload/ >>>>> >>>>> There are also htmlized versions available at: >>>>> https://tools.ietf.org/html/draft-ietf-ospf-link-overload-07 >>>>> https://datatracker.ietf.org/doc/html/draft-ietf-ospf-link-overload- >>>>> 0 >>>>> 7 >>>>> >>>>> A diff from the previous version is available at: >>>>> https://www.ietf.org/rfcdiff?url2=draft-ietf-ospf-link-overload-07 >>>>> >>>>> >>>>> Please note that it may take a couple of minutes from the time of >>>>>submission until the htmlized version and diff are available at >>>>>tools.ietf.org. >>>>> >>>>> Internet-Drafts are also available by anonymous FTP at: >>>>> ftp://ftp.ietf.org/internet-drafts/ >>>>> >>>>> _______________________________________________ >>>>> 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 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 mailing list >OSPF@ietf.org >https://www.ietf.org/mailman/listinfo/ospf
- [OSPF] I-D Action: draft-ietf-ospf-link-overload-… internet-drafts
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Shraddha Hegde
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Ketan Talaulikar (ketant)
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Peter Psenak
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Acee Lindem (acee)
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Shraddha Hegde
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Acee Lindem (acee)
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Shraddha Hegde
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Acee Lindem (acee)
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Acee Lindem (acee)
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Julien Meuric
- Re: [OSPF] I-D Action: draft-ietf-ospf-link-overl… Shraddha Hegde