Re: [Pce] draft-leroux-pce-of-00.txt

[JP Vasseur <[e-mail]>]

Hi Jerry,

On Mar 15, 2007, at 10:55 PM, ASH, GERALD R, ATTLABS wrote:

> Hi JL,
>
>>> IMO an important missing PCECP requirement is identified in
>>> http://www.ietf.org/internet-drafts/draft-ietf-pce-pcep-07.txt
>>>  Appendix A (Compliance with the PCECP Requirement Document):
>>>
>>> "   Here is the list of currently unsatisfied requirements:
>>>
>>>    o  Allow to select/prefer from advertised list of standard
>>> objective
>>>       functions/options
>>>
>>>    o  Allow to customize objective function/options
>>>
>>>    o  Support "unsynchronized" & "synchronized" objective functions"
>>>
>>> They all deal with the missing 6 objective functions required
>>> in RFC 4657, and are an important omission in PCEP, so far.
>>

Let's try to step back for a minute.
1) PCEP has been designed so as to support the functionalities listed  
above.
RFC 4657 does not mandate to define the objective functions but to  
allow to
select objective functions, ... and that is clearly feasible with the  
PCEP design.
As such I don't see any particular issues.
2) Yes, defining such functions is a good idea, thus the proposed  
draft, which is
not at this point a WG ID indeed. Thanks for helping out on the  
content of this draft.
3) Whether to add those functions and other features in the base spec  
has indeed
been debated during the last two WG meetings and the agreement was to
freeze the current spec in order to stabilize the specification, wait  
to see implementations,
interop reports, ... As you know, we have to draw the line somewhere  
and if we keep
adding feature, the base protocol spec will not stabilize. The PCE  
being a new path
computation concept, it is crucial to first stabilize a set of core  
features, acquire some
experience based on deployments rather than keep adding features.

Does that make sense ?

Cheers.

JP.

>>
>> In montreal we indicated that objective functions would not
>> be covered in the base PCEP spec.
>> There was no objection. This was recalled in San Diego, again
>> no objection...
>
> Well that doesn't cast it in concrete, I'll register my objection.
> Without objective functions, PCE would not be able to do much to
> optimize path computation.  I think it's important for PCEP to include
> the objective functions required in the PCECP generic requirements in
> the base PCEP spec.
>
>>> You say that PCEP is 'stable' so you don't want to add them
>>> there?
>>
>> What I say is that this would create dependency between PCEP
>> and OF drafts which is not good. The base PCEP draft should
>> not have any dependency with other drafts.
>>
>>> Does that mean no further changes to PCEP before
>>> WGLC?
>>
>> Definitely no!
>>
>> But, again, note that it was agreed that objective functions
>> would not be covered in the base spec.
>
> See above comments.
>
>>> I don't think other new drafts (e.g.,
>>> draft-lee-pce-global-concurrent-optimization-02.txt) that
>>> specify perhaps *new* PCEP requirements, should be satisfying
>>> the original RFC 4657 PCECP requirements on PCEP.
>>
>> Why?
>>
>> Draft-lee specifies two objective functions listed in 4657,
>> where is the problem?
>
> Several.  No rationale to put generic PCECP requirements in some other
> draft besides the base PCEP draft.  The draft isn't a WG draft.  There
> isn't any compelling reason to not specify the objective functions in
> the base PCEP draft.
>
>>> You also
>>> say 'We can add other synchronized objective functions in the
>>> next revision of the gco draft.'  I don't think that's the
>>> right place to satisfy the PCECP requirements.
>>
>> Why?
>
> See above comments.
>
> Thanks,
> Regards,
> Jerry
>
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