Re: [PCN] hope changes in PCN drafts will not affect validity assumptions in draft-ietf-tsvwg-rsvp-pcn

[<[e-mail]>]

surely we're trying to finish the work off, rather than opening up new functionality?

'not being precluded' is very different from 'will try to support'!

on your first suggestion:
I'm not sure what you mean by 'more than one PCN aware behaviour aggregate between two edge nodes'. If you mean, several forwarding priorities I'd disagree; if you mean several DSCPs each with the same fwding priority, not sure I understand the use case; if you mean ECMP - maybe, but I don't understand what solution you're thinking of (is it something in http://www.bobbriscoe.net/projects/ipe2eqos/pcn/papers/draft-briscoe-tsvwg-cl-architecture-04.txt or some new idea?)
I'm sceptical, but not sure I understand what your scenario is

on your second point:
we have always said that PCN is for inelastic flows. with your flow slowing, this is changing the model. we have always said that flow termination is highly unusual action taken in extreme cases when somethng has gone wrong - normally, admission control, plus sensible utilisation, plus flow aggregation, plus that there is lower priority traffic that can flex, should keep the network in a safe operating region. To me, flow slowing sounds like an optimisation that isn't worthwhile. 
So I'm pretty dubious about this one.

thanks,
phil
________________________________________
From: [e-mail] [[e-mail]]
Sent: 25 March 2012 10:15
To: Eardley,PL,Philip,DUB8 R; [e-mail]
Subject: RE: [PCN] hope changes in PCN drafts will not affect validity assumptions in draft-ietf-tsvwg-rsvp-pcn

Hi Phil,

The first assumption actuallu allows the possibility of having more than one PCN aware behaviour aggregates being supported between two edge nodes. I think that this is/was not precluded from the current specs.
Or I am wrong?

The second assumption regarding flow slowing is new, but in my opinion was/is not precluded from the current specs.
Or I am wrong?
Note that the goal of flow termination, which is to reduce the bandwidth associated with one PCN aware behaviour aggregate is not changed in order to solve the congestion, i.e., it remains valid.
So the assumption allows the possibility of instead of terminating flows reduce the bandwidth of some flows and achieve the same goal!

Best regards

________________________________________
Van: [e-mail] [[e-mail]]
Verzonden: zaterdag 24 maart 2012 18:04
Aan: Karagiannis, G. (EWI); [e-mail]
Onderwerp: RE: [PCN] hope changes in PCN drafts will not affect validity assumptions in draft-ietf-tsvwg-rsvp-pcn

It's Quite a while since I read the edge behavior docs but I don't understand these assumptions. An iea is ask the traffic between two boundary nodes, what's the idea of several? The pcn architecture talks about admission control and flow termination, flow slowing is an interesting idea but seems different to me
________________________________________
From: [e-mail] [[e-mail]] On Behalf Of [e-mail] [[e-mail]]
Sent: 24 March 2012 05:19
To: [e-mail]
Subject: [PCN] hope changes in PCN drafts will not affect validity assumptions in draft-ietf-tsvwg-rsvp-pcn

Hi all,



>From what I can recall the edge behavior drafts could proceed with their publication based on the assumption that the draft-ietf-tsvwg-rsvp-pcn will be standardized in tsvwg.

Due to some changes that are being implemented lately the validity of two main assumptions in the draft-ietf-tsvwg-rsvp-pcn might not hold anymore.
However, this is not clear to me.
I hope that the validity of the following two main assumptions considered in draft-ietf-tsvwg-rsvp-pcn are still valid, without breaking the PCN SM and CL edge behavior specifications:

Assumption 1: More than one IEAs between same pair of PCN edge nodes should be supported, each of them using a different PHB-ID value
Why?: A requesting individual flow has a higher chance to be admitted to an IEA that is NOT in PCN-admission-state
How? When IEA supported by a PCN-ingress-node is in PCN-admission state, then based on local policy, requesting e2e RSVP session (individual flow) should be either rejected or mapped to another IEA that is NOT in PCN-admission-state

Assumption 2: PCN-ingress-node should be able to reduce bandwidth of an individual flow without terminating the flow
Why?: flows will not be terminated unnecessary and at the same time the IEA bandwidth is reduced to solve the severe congestion
How?: When for IEA supported by PCN-ingress-node incoming traffic needs to be reduced then:
based on a local policy and for same IEA, selects a number of e2e RSVP sessions (individual flows) to be either terminated or reserved bandwidth of e2e RSVP sessions (individual flows) is reduced

If these assumptions are not valid anymore then we might need to do changes in the not yet published PCN drafts!

Best regards,
Georgios