Re: [CCAMP] Objective function draft
Julien Meuric <julien.meuric@orange.com> Wed, 19 September 2012 13:54 UTC
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Date: Wed, 19 Sep 2012 15:53:56 +0200
From: Julien Meuric <julien.meuric@orange.com>
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To: Lou Berger <lberger@labn.net>
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Subject: Re: [CCAMP] Objective function draft
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Lou, Gert, You are right: my previous 1st sentence was too specific, "inter-layer signaling" should be replaced by "client-server signaling". We agree on that, it was not my intention to question that part. Regards, Julien Le 19/09/2012 13:46, Lou Berger a écrit : > Julien, > Just to add to Gert's point about UNI/ENNI not being related to layers; > you can find the same terminology in the context of MPLS-TP, see RFCs > 6215 and 5921. We already have RFC4208 which provides the foundation of > a GMPLS UNI, and the related RFC5787(bis) work. > > I personally see this as the foundation and context for this (and the > beeram) discussion. > > Lou > > On 9/19/2012 3:14 AM, Gert Grammel wrote: >> Hi Julien, >> >> Most of the discussions about UNI/ENNI are confusing. Let's start with the remark that UNI/ENNI are terms defined in G.709 and do not relate to layers. They are reference points. You can think to place them in the middle of the fiber between a router and a ROADM. Since it is just fiber, it is pretty clear that no layer crossing is happening there. >> In IETF we have the overlay concept which also doesn't relate to layers but to an administrative domain. Hence an operator can choose to place a 'GMPLS-UNI' where he wants. >> Admittedly common wisdom places UNI as inter-layer communication and here is where confusion starts. AFAIK the terms UNI-C and UNI-N as well as the notion of a 'UNI-protocol' have been brought up in OIF. For whatever it is or was, initial UNI was from SDH/SONET client to SDH/SONET server, hence again no layer crossing even at the protocol level. >> >> If different layer switching is involved on both sides of an interface, the best reference is RFC5212 (requirements) and RFC6001. They define a consistent multi-layer switching and adaptation model. >> >> So in order to stay inside a consistent terminology we decided to go strictly with IETF terminology. That's the best we can do for now. >> >> To your points: >> - the routing task involves both the IGP and the signaling protocol, especially in case of loose hops or crankbacks; >> --> what you mean with routing task? Is it the routing process itself or something more? >> >> - the objective function only makes sense per LSP, which allows to consider it in LSP-related protocols (PCEP, RSVP-TE... as opposed to IGPs or LMP). >> --> an objective function could make sense per LSP if routing information is insufficient. It starts with the assumption that a router down the road may be able to find a better path than what the ingress router does. Given that the ingress has no means to verify if the objective has been followed this may turn out to become a debugging nightmare. >> >> Gert >> >> >> >> >> -----Original Message----- >> From: JP Vasseur (jvasseur) [mailto:jvasseur@cisco.com] >> >> I an completely sharing Julien's point of view. >> >> JP Vasseur >> Cisco Fellow >> >> Sent from my iPhone >> >> On 18 sept. 2012, at 05:27, "Julien Meuric" <julien.meuric@orange.com> wrote: >> >>> Hi Gert. >>> >>> As Daniele has just said, almost all the information in an inter-layer signaling can be seen as input/constraints to the routing process. The IGP-TE brings some link-state information to some network nodes so as to achieve path computation; the result is used in the signaling protocol, on a per LSP basis. I would said that: >>> - the routing task involves both the IGP and the signaling protocol, >>> especially in case of loose hops or crankbacks; >>> - the objective function only makes sense per LSP, which allows to consider it in LSP-related protocols (PCEP, RSVP-TE... as opposed to IGPs or LMP). >>> >>> I feel that draft-beeram-ccamp-gmpls-_enni_ is clearly introducing some great confusion in the vocabulary: it is a superset of draft-beeram-ccamp-gmpls-_uni_-bcp while removing the pointer to the ITU-T reference point. A possible option is just to avoid those terms and stick to protocols, namely RSVP-TE and IGP-TE. >>> >>> Regards, >>> >>> Julien >>> >>> >>> Le 17/09/2012 23:22, Gert Grammel a écrit : >>>> Hi George, >>>> >>>> The objective function is in the end a routing information. Mixing routing and signaling in one protocol is something I don't feel comfortable with. >>>> >>>> In other words, if routing is needed between client and server, UNI >>>> is the wrong choice. ENNI should be considered instead and Draft-beeram-ccamp-gmpls-enni would be a good starting point. >>>> >>>> >>>> Gert >>>> >>>> >>>> >>>> ________________________________________ >>>> From: ccamp-bounces@ietf.org on behalf of George Swallow (swallow) >>>> >>>> Hi Julien - >>>> >>>> On 9/17/12 9:37 AM, "Julien Meuric" <julien.meuric@orange.com> wrote: >>>> >>>>> Hi George. >>>>> >>>>> Sorry for the late response. You are right: the minutes are not >>>>> enough to trace the full discussion (which we also resumed right >>>>> after the meeting). Let us start by thanking Adrian (as AD? former PCE co-chair? >>>>> author of... ;-) ) for bringing the PCE-associated vocabulary to a >>>>> common understanding. >>>>> >>>>> Actually my concern is sustained by 2 points: >>>>> >>>>> 1- The scope of the draft is about giving control of the routing >>>>> objective function to the client node facing a transport layer. I >>>>> see already several existing solution to achieve it: >>>>> - a PCEP request from the signaling head node is an option (which is >>>>> associated to the advertisement of the supported objectives in >>>>> PCEP); >>>>> - building IGP adjacencies between client and transport edge nodes >>>>> (a.k.a. "border model") is another one. >>>>> In this context, it do not think extending RSVP-TE for this kind of >>>>> application is worth the effort, since the requirement can already >>>>> be addressed. >>>> As I understand it, in the optical and OTN cases, the border model >>>> would not be popular as in many organizations this crosses political >>>> boundaries. >>>> >>>> The point of the draft is to keep the UNI implementation simple and >>>> not require a PCEP on the uni-c or necessarily on the uni-n. We will >>>> keep the format aligned so if the UNI-N needs to make a request of a >>>> PCS, it can do so rather simply. >>>>> 2- There are cases when previous options are ruled out of a given >>>>> deployment. I do believe that it is not simply due to protocol >>>>> exclusion, but rather to the fact that the SP wants transport >>>>> routing decisions to remain entirely within the transport network >>>>> (in order to fully leave the routing policy in the hands of people >>>>> doing the layer dimensioning). Thus, I feel this trade-off in path >>>>> selection tuning is rather unlikely to happen and I fear we may be >>>>> talking about RSVP-TE over-engineering here. >>>> The idea is simply to allow the client to express its needs/wishes. >>>> The UNI-N remains in control. By policy it can use the objective >>>> function or not. Further if it does use the objective function and >>>> fails to find a path it can either say that there was no path or it >>>> proceed to setup what it can. >>>> >>>>> (That is also why I preferred to consider your I-Ds separately >>>>> during the CCAMP meeting.) >>>> Agreed. I will ask for separate slots. The discussion at the end >>>> was rather disjointed. >>>> >>>>> However, my comments are mostly related to the client/transport >>>>> relationship. If the I-D is extended to cover more use cases with >>>>> wider scopes (Adrian has made interesting suggestions), turning the >>>>> overlay interconnection into one among a longer list, then my >>>>> conclusion may be different. >>>> I'm happy to widen the scope in this way. >>>> >>>> ...George >>>> >>>>> Regards, >>>>> >>>>> Julien >>>>> >>>>> >>>>> Le 11/09/2012 21:28, George Swallow (swallow) a écrit : >>>>>> Julien - >>>>>> >>>>>> Reading the CCAMP notes (which capture little of the actual >>>>>> discussion) I see that there may have been a perception in the room >>>>>> that PCE functionality at the UNI-N was assumed (actual or proxy). >>>>>> >>>>>> This is not the case. The reason for our draft is that with the >>>>>> UNI, much of the functionality that resides at the headend is moved >>>>>> to the UNI-N. So the UNI-C needs a way to express an objective >>>>>> function even if there is no PCE. >>>>>> >>>>>> Operationally it seems burdensome to require a PCEP at the UNI-C >>>>>> and a PCEP at the UNI-N, when all that is being done is enabling >>>>>> the UNI-N to perform what the client would do if it were connected >>>>>> to the network via a normal link. >>>>>> >>>>>> Do you still object to the draft? >>>>>> >>>>>> Thanks, >>>>>> >>>>>> ŠGeorge >>>> _______________________________________________ >>>> CCAMP mailing list >>>> CCAMP@ietf.org >>>> https://www.ietf.org/mailman/listinfo/ccamp >>>> >>>> >>> _______________________________________________ >>> CCAMP mailing list >>> CCAMP@ietf.org >>> https://www.ietf.org/mailman/listinfo/ccamp >> >> _______________________________________________ >> CCAMP mailing list >> CCAMP@ietf.org >> https://www.ietf.org/mailman/listinfo/ccamp >> >> >> >>
- Re: [CCAMP] Objective function draft George Swallow (swallow)
- [CCAMP] Objective function draft George Swallow (swallow)
- Re: [CCAMP] Objective function draft Adrian Farrel
- Re: [CCAMP] Objective function draft George Swallow (swallow)
- Re: [CCAMP] Objective function draft Daniele Ceccarelli
- Re: [CCAMP] Objective function draft Julien Meuric
- Re: [CCAMP] Objective function draft George Swallow (swallow)
- Re: [CCAMP] Objective function draft Dieter Beller
- Re: [CCAMP] Objective function draft Gert Grammel
- Re: [CCAMP] Objective function draft Dieter Beller
- Re: [CCAMP] Objective function draft Julien Meuric
- Re: [CCAMP] Objective function draft Daniele Ceccarelli
- Re: [CCAMP] Objective function draft Julien Meuric
- Re: [CCAMP] Objective function draft JP Vasseur (jvasseur)
- [CCAMP] R: Objective function draft BELOTTI, SERGIO (SERGIO)
- Re: [CCAMP] Objective function draft George Swallow (swallow)
- Re: [CCAMP] Objective function draft Vishnu Pavan Beeram
- Re: [CCAMP] Objective function draft Ong, Lyndon
- Re: [CCAMP] Objective function draft Igor Bryskin
- Re: [CCAMP] Objective function draft John E Drake
- Re: [CCAMP] UNI/NNI (was: Objective function draf… Julien Meuric
- Re: [CCAMP] UNI/NNI (was: Objective function draf… Daniele Ceccarelli
- Re: [CCAMP] Objective function draft Gert Grammel
- Re: [CCAMP] Objective function draft John E Drake
- Re: [CCAMP] UNI/NNI Julien Meuric
- Re: [CCAMP] Objective function draft Lou Berger
- Re: [CCAMP] Objective function draft Julien Meuric
- Re: [CCAMP] Objective function draft John E Drake
- Re: [CCAMP] Objective function draft Julien Meuric
- Re: [CCAMP] Objective function draft Igor Bryskin
- Re: [CCAMP] Objective function draft Gert Grammel
- Re: [CCAMP] Objective function draft Lou Berger
- Re: [CCAMP] Objective function draft Igor Bryskin
- Re: [CCAMP] Objective function draft Lou Berger
- Re: [CCAMP] Objective function draft Dieter Beller
- Re: [CCAMP] Objective function draft John E Drake
- Re: [CCAMP] Objective function draft Igor Bryskin