Re: [CCAMP] Objective function draft
Lou Berger <lberger@labn.net> Wed, 19 September 2012 19:27 UTC
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Date: Wed, 19 Sep 2012 15:27:30 -0400
From: Lou Berger <lberger@labn.net>
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To: Igor Bryskin <IBryskin@advaoptical.com>
References: <305443B66F0CD946A3107753337A0311F533@CH1PRD0511MB431.namprd05.prod.outlook.com>, <505868A4.6020802@orange.com> <ECF78C00-0A85-4C81-AFF4-529C6996DEDF@cisco.com> <305443B66F0CD946A3107753337A0311012339@CH1PRD0511MB431.namprd05.prod.outlook.com> <5059B09B.3050005@labn.net> <5059CE74.6030803@orange.com> <5E893DB832F57341992548CDBB333163A63321B55E@EMBX01-HQ.jnpr.net> <5059EBB8.8010304@orange.com>, <CDAC6F6F5401B245A2C68D0CF8AFDF0A1909DC81@atl-srv-mail10.atl.advaoptical.com> <305443B66F0CD946A3107753337A03110124E9@CH1PRD0511MB431.namprd05.prod.outlook.com> <505A0D6C.5000402@labn.net> <CDAC6F6F5401B245A2C68D0CF8AFDF0A1909DCC2@atl-srv-mail10.atl.advaoptical.com>
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Cc: "ccamp@ietf.org" <ccamp@ietf.org>
Subject: Re: [CCAMP] Objective function draft
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Igor, I completely agree, but don't see this clearly articulated in the current draft. Lou On 9/19/2012 2:36 PM, Igor Bryskin wrote: > Lou, > > In the context of ENNI/UNI the multi-domain aspect is important, the > multi-layer aspect is not important at all. Although, generally > speaking, network and client physically exist in different layers > (which by the way not always the case) they always peer each other in > the same (client) layer, virtual topology exposed to the client also > belongs to the same (client) layer. > > Igor > > -----Original Message----- > From: Lou Berger [mailto:lberger@labn.net] > Sent: Wednesday, September 19, 2012 2:23 PM > To: Gert Grammel; Igor Bryskin; John E Drake > Cc: Julien Meuric; ccamp@ietf.org > Subject: Re: [CCAMP] Objective function draft > > Gert/Igor/John, > I sympathize with Julien's comments. It seems to me that the draft intermingles the concepts of multi-domain (which includes UNI/ENNI) and multi-layer (which includes, for example MPLS over optical). While there certainly is much commonality in mechanisms, I think the draft could be clearer on the conceptual definitions and discussions... > > Lou > > On 9/19/2012 1:00 PM, Gert Grammel wrote: >> Lets try to be more precise and write instead: >> >> - "this document uses the term 'External Network Interface (E-NNI)' to describe this interface between two network domains. Both domains may switch on different layers and form a client/server relationship. >> >> Although I agree with better readability of the BCP, we have to address the concern of the WG and be precise. So let's try perfecting our language ... >> >> Gert >> >> ________________________________________ >> From: ccamp-bounces@ietf.org on behalf of Igor Bryskin >> Sent: Wednesday, September 19, 2012 12:25:58 PM >> To: Julien Meuric; John E Drake >> Cc: ccamp@ietf.org >> Subject: Re: [CCAMP] Objective function draft >> >> Hi Julien, >> >> This should say: >> - "this document uses the term 'External Network Network Interface (E-NNI)' to describe this interface between a client and server network domains". >> >> The important thing is that there is a TE domain demarcation between network and its client. The similar demarcation exists between adjacent network domains in a multi-domain environment. In either case the domains are inter-connected via access/inter-domain links in the data plane and GMPLS-ENNI in the control plane. >> >> Hope this helps. >> Igor >> >> >> >> -----Original Message----- >> From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On Behalf >> Of Julien Meuric >> Sent: Wednesday, September 19, 2012 11:59 AM >> To: John E Drake >> Cc: ccamp@ietf.org >> Subject: Re: [CCAMP] Objective function draft >> >> Hi John. >> >> Let me quote the introduction of draft-beeram-ccamp-gmpls-enni: >> - "this memo describes how introducing a representation of server >> layer network resources into a client layer network topology enhances >> client layer networking in the overlay model"; >> - "this document uses the term 'External Network Network Interface (E-NNI)' to describe this interface between a client and server network". >> >> E-NNI for client-server (and overlay): this is exactly where I start >> to get confused... (draft-beeram-ccamp-gmpls-uni-bcp used to be easier >> to follow on this.) >> >> Julien >> >> >> On 09/19/2012 16:03, John E Drake wrote: >>> Julien, >>> >>> This is the terminology we have been using in draft-beeram. >>> >>> Yours irrespectively, >>> >>> John >>> >>> >>>> -----Original Message----- >>>> From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On >>>> Behalf Of Julien Meuric >>>> >>>> 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 >>>>>> >>>>>> >>>>>> >>>>>> >>>> _______________________________________________ >>>> 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 >> >> >> _______________________________________________ >> 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