Re: [PCN] Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03

Tom Taylor <tom.taylor.stds@gmail.com> Thu, 15 November 2012 22:09 UTC

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Date: Thu, 15 Nov 2012 17:09:08 -0500
From: Tom Taylor <tom.taylor.stds@gmail.com>
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To: Bob Briscoe <bob.briscoe@bt.com>
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Cc: PCN IETF list <pcn@ietf.org>, anuragb@cisco.com, tsvwg@ietf.org, rsvp-dir@ietfa.amsl.com
Subject: Re: [PCN] Redundant aggregate reservations: draft-ietf-tsvwg-rsvp-pcn-03
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OK, I guess I see your point. I was too focussed on the calculations 
that are done at the Decision Point.

It makes me wonder if I should revive that piggy-backing edge behaviour 
draft I once started.

On 15/11/2012 4:02 PM, Bob Briscoe wrote:
> Tom,
>
> The RSVP message I'm proposing doesn't say "Never mind the SESSION in
> this message, I'm related to every flow with the same first hop". It
> says "These are the marking probabilities for the SESSION in this
> message". Then the PCN-ingress (not the message) infers that all other
> flows that share the same aggregate will share the same marking
> probability, because PCN marking on interior nodes is random and unbiased.
>
> It's a subtle distinction, but it preserves the semantics of RSVP
> messages, without the three disadvantages of setting up an RSVP
> aggregate that I mentioned.
>
> You will have seen from the rest of the message that I have not rejected
> the concept of aggregation, I am merely saying that the PCN-ingress and
> PCN-egress can hold the concept internally.
>
>
> Bob
>
> At 16:42 15/11/2012, Tom Taylor wrote:
>> I'm not sure the semantics of the PCN information -- particularly as
>> it relates to flow termination -- are correct without some sort of
>> concept of aggregation. Or can you really define an RSVP object that
>> has semantics "Never mind the SESSION in this message, I'm related to
>> every flow with the same first hop"?
>>
...