Re: [CCAMP] Objective function draft

"George Swallow (swallow)" <swallow@cisco.com> Wed, 12 September 2012 13:34 UTC

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From: "George Swallow (swallow)" <swallow@cisco.com>
To: "adrian@olddog.co.uk" <adrian@olddog.co.uk>, "'Julien Meuric'" <julien.meuric@orange.com>
Thread-Topic: [CCAMP] Objective function draft
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Date: Wed, 12 Sep 2012 13:34:45 +0000
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Subject: Re: [CCAMP] Objective function draft
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Adrian -

I think we are quite in agreement!  The only difference is that I was using PCE  in a narrower sense of an entity that also runs PCEP.  But reading the PCE architecture document, I see that you are correct.

…George



From: Adrian Farrel <adrian@olddog.co.uk<mailto:adrian@olddog.co.uk>>
Reply-To: Adrian Farrel <adrian@olddog.co.uk<mailto:adrian@olddog.co.uk>>
Date: Tuesday, September 11, 2012 7:39 PM
To: Cisco Employee <swallow@cisco.com<mailto:swallow@cisco.com>>, Julien Meuric <julien.meuric@orange.com<mailto:julien.meuric@orange.com>>
Cc: "ccamp@ietf.org<mailto:ccamp@ietf.org>" <ccamp@ietf.org<mailto:ccamp@ietf.org>>
Subject: RE: [CCAMP] Objective function draft

<individual contributor mode>

I'm hoping that you have looked at RFC 5623 that describes some approaches to inter-layer networking using PCE.

But it seems that perhaps you are more interested in the per-domain PCE mechanism (RFC 5152) and that you have observed that the OF that would be used in each domain to select the path is not currently available because it is missing from RSVP-TE. That seems to me to be a perfectly reasonable thing to add to RSVP-TE and I think it enables and supports the work of the PEC working group without any conflict, but I would hope that you share definitions of OFs with the PCE WG.

And one last point, when you say

> even if there is no PCE

you misunderstand the PCE architecture. If you are computing a path (in an LSR) you are de facto providing PCE functionality. There is no need in the architecture (and thus the implementation) to expose an external (PCEP) interface in order to be logically providing PCE function, and this is *exactly* why you want access to the OF.

However, you would perhaps do better to absorb this ambivalence and note that you need the OF and Metric whether or not the PCE is external.

All of which you may take as general support for your idea, but a feeling that the I-D is not happily written and deviating too much from shared context with PCE.

Cheers,
Adrian

From: ccamp-bounces@ietf.org<mailto:ccamp-bounces@ietf.org> [mailto:ccamp-bounces@ietf.org] On Behalf Of George Swallow (swallow)
Sent: 11 September 2012 20:29
To: Julien Meuric
Cc: ccamp@ietf.org<mailto:ccamp@ietf.org>
Subject: [CCAMP] Objective function draft

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,

…George