Re: [CCAMP] draft-ali-ccamp-rc-objective-function-metric-bound-03.txt
Fatai Zhang <zhangfatai@huawei.com> Tue, 13 August 2013 01:57 UTC
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From: Fatai Zhang <zhangfatai@huawei.com>
To: John E Drake <jdrake@juniper.net>, Daniele Ceccarelli <daniele.ceccarelli@ericsson.com>, "Matt Hartley (mhartley)" <mhartley@cisco.com>, "CCAMP (ccamp@ietf.org)" <ccamp@ietf.org>
Thread-Topic: [CCAMP] draft-ali-ccamp-rc-objective-function-metric-bound-03.txt
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Date: Tue, 13 Aug 2013 01:54:02 +0000
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Subject: Re: [CCAMP] draft-ali-ccamp-rc-objective-function-metric-bound-03.txt
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Hi John, Agree. We should figure out use case, applicability, requirement, framework, etc, and then go to solution. Otherwise, it is really not a good idea to drive something by some specific solutions. Best Regards Fatai -----Original Message----- From: John E Drake [mailto:jdrake@juniper.net] Sent: Tuesday, August 13, 2013 12:56 AM To: Daniele Ceccarelli; Matt Hartley (mhartley); Fatai Zhang; CCAMP (ccamp@ietf.org) Cc: Adrian Farrel Subject: RE: [CCAMP] draft-ali-ccamp-rc-objective-function-metric-bound-03.txt Daniele, Comments inline. However, the discussions since Berlin on UNI enhancements and/or adding additional information related to path computation into the PATH message lead me to the conclusion that we have a problem in CCAMP and that we really should suspend all solutions related work until we have a better idea of the problem we wish to solve. If you don't think we have a problem, please consider the list of active CCAMP drafts: http://datatracker.ietf.org/doc/draft-ietf-ccamp-lsp-attribute-ro/ http://datatracker.ietf.org/doc/draft-ietf-ccamp-lsp-diversity/ http://datatracker.ietf.org/doc/draft-ietf-ccamp-rsvp-te-srlg-collect/ http://datatracker.ietf.org/doc/draft-ietf-ccamp-te-metric-recording/ http://datatracker.ietf.org/doc/draft-ali-ccamp-extended-srlg/ http://datatracker.ietf.org/doc/draft-ali-ccamp-gmpls-uni-error-notification/ http://datatracker.ietf.org/doc/draft-ali-ccamp-lsp-inquiry/ http://datatracker.ietf.org/doc/draft-ali-ccamp-rc-objective-function-metric-bound/ http://datatracker.ietf.org/doc/draft-bardalai-ccamp-overlay-path-comp/ http://datatracker.ietf.org/doc/draft-ceccadedios-ccamp-overlay-use-cases/ http://datatracker.ietf.org/doc/draft-dhody-ccamp-rsvp-te-domain-subobjects/ http://datatracker.ietf.org/doc/draft-fedyk-ccamp-uni-extensions/ http://datatracker.ietf.org/doc/draft-gandhi-ccamp-gmpls-restoration-lsp/ Yours Irrespectively, John > -----Original Message----- > From: Daniele Ceccarelli [mailto:daniele.ceccarelli@ericsson.com] > Sent: Monday, August 12, 2013 7:29 AM > To: John E Drake; Matt Hartley (mhartley); Fatai Zhang; CCAMP > (ccamp@ietf.org) > Subject: RE: [CCAMP] draft-ali-ccamp-rc-objective-function-metric-bound- > 03.txt > > Hi John, all, > > I think there are cases in which the PCEP can't solve the issue. Suppose for > example the simple network below > > C1 --- C2 --- C3 C4 --- C5 --- C6 > \ / > S1 --- S2 --- S3 > > Where Cx are the client nodes and Sx the server nodes and C3-S1 and S3-C4 > the UNIs. > The usual behavior for the setup of an LSP in the client domain between C1 > and C6 consists on 1. "asking" C3 to setup a link in the client layer between > C3 and C4 and 2. after its provisioning, "asking" C1to setup an LSP between > C1 and C6 using the link between C3 and C4. JD: No, that's incorrect. The C1-C6 Path message arrives at C3. It triggers C3 to establish a C3-C4 LSP. After this LSP is established, C3 forwards the C1-C6 Path message to C4. We already have CCAMP drafts from, I believe, Cyril and/or Fatai that describe how to embed the desired characteristics of the C3-C4 LSP within the ERO of the C1-C6 Path message. > > If you suppose to have a simpler approach consisting on a single step, it > would be possible to "ask" C1 to setup an end to end LSP between C1 and C6 > with loose ERO C1-C3-C4-C6. JD: See above. This has been a part of GMPLS since its inception. > > In the first case the trigger on C3 is provided by the operator with given > constraints (e.g. Objective functions and/or TE metric bounds) and it would > be easy to inject them into a PCEP request towards the PCE of the server > domains, but what happens in the second case? The operator only issues a > command to C1, which starts a signaling procedure. The RSVP-TE message > reaches C3 and triggers the setup of the link C3-C4 over the UNI. JD: See above. The second case is actually the GMPLS baseline behavior. > > IMHO putting the Objective Functions into RSVP-TE is useful to "convey" > such path computation requirements from C1 to C3. Once the PATH message > reaches C3, it can ask S1 to compute the path towards C4 via RSVP-TE or can > ask the server layer PCE via PCEP. JD: In addition to what is described above, it is also possible for C1 to use PCEP to expand the C3-C4 ERO and place the key associated with this expansion in the ERO of the C1-C6 Path message. > > This is one of the two reasons why I think that Objective Functions and TE > metric Bounds could be useful in RSVP-TE. The second one is that I agree > with Matt when saying that not in all cases the client nodes will be allowed to > access the server layer PCE. JD: The draft is proposing to embed PCEP within signaling. By definition, this *is* allowing the client to access the server layer PCE. This is no different than allowing the client to access the server layer PCE without embedding PCE within signaling. > > BR > Daniele > > > > > -----Original Message----- > > From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On > Behalf > > Of John E Drake > > Sent: venerdì 9 agosto 2013 23:23 > > To: Matt Hartley (mhartley); Fatai Zhang; CCAMP (ccamp@ietf.org) > > Subject: Re: [CCAMP] > > draft-ali-ccamp-rc-objective-function-metric-bound- > > 03.txt > > > > PCEP can be deployed whenever the server network wishes to provide a > > path computation service. What possible advantage to anyone is gained > > by embedding PCEP in RSVP-TE signaling? > > > > Yours Irrespectively, > > > > John > > > > > -----Original Message----- > > > From: Matt Hartley (mhartley) [mailto:mhartley@cisco.com] > > > Sent: Friday, August 09, 2013 1:53 PM > > > To: Fatai Zhang; John E Drake; CCAMP (ccamp@ietf.org) > > > Cc: Matt Hartley (mhartley) > > > Subject: RE: [CCAMP] > > > draft-ali-ccamp-rc-objective-function-metric-bound- > > > 03.txt > > > > > > Fatai, John, > > > > > > I don't think you can guarantee that PCE will be deployed absolutely > > > everywhere, or that you can guarantee the client will be permitted > > > access to the server PCE when it is. In those cases, this draft is useful. > > > > > > Cheers > > > > > > Matt > > > > > > > Hi John, > > > > > > > > Completely agree. > > > > > > > > I also raised this comment in front of the mic during Berlin meeting. > > > > > > > > > > > > > > > > Best Regards > > > > > > > > Fatai > > > > > > > > > > > > -----Original Message----- > > > > From: ccamp-bounces@ietf.org [mailto:ccamp-bounces@ietf.org] On > > > Behalf > > > > Of John E Drake > > > > Sent: Friday, August 09, 2013 1:49 AM > > > > To: CCAMP (ccamp@ietf.org) > > > > Subject: [CCAMP] > > > > draft-ali-ccamp-rc-objective-function-metric-bound-03.txt > > > > > > > > Hi, > > > > > > > > I have a real concern with this draft because it appears to be > > > > heading us down the road of re-inventing PCEP in RSVP signaling > > > > with the dubious justification that it is needed in those > > > > situations in which a PCE is not available. However, if you > > > > re-invent PCEP in RSVP signaling, then you have effectively > > > > ensured that there are no situations in which a PCE or its signaling > equivalent are not available. > > > > > > > > Why is this better than simply ensuring that a PCE is available in > > > > those situations in which it is needed? > > > > > > > > Yours Irrespectively, > > > > > > > > John > > > > > > > > > > > > _______________________________________________ > > > > 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] draft-ali-ccamp-rc-objective-function-met… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Fatai Zhang
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Zafar Ali (zali)
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Zafar Ali (zali)
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Matt Hartley (mhartley)
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Lou Berger
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Lou Berger
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Daniele Ceccarelli
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Fatai Zhang
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Daniele Ceccarelli
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Fatai Zhang
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Daniele Ceccarelli
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Zafar Ali (zali)
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Gert Grammel
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… Zafar Ali (zali)
- Re: [CCAMP] draft-ali-ccamp-rc-objective-function… John E Drake