Subject: RE: [PCN] PCN updated charter

From: "Anna Charny \(acharny\)" <[email-masked]>
Date: Thu, 30 Nov 2006 13:20:53 -0500

Hi Kwok,
 
>>Anna begin>
>>
>>PWE3-related deployment model has already been taken out of the
updated 
>>charter, based on the BOF input.
>>
>>As to SIP-related one  -  there is one aspect of it that actually 
>>potentially affects the marking at the ingress node, namely the 
>>aggregation assumptions, and especially aggregation level on a 
>>per-ingress-egress aggregate.  This specific model is likely to assume

>>both lower levels of aggregation on the PCN internal links, but 
>>especially on a per-ingress-egress pair basis. From the work available

>>by now it seems relatively clear that if the core marking is to 
>>accommodate this,  the decision on *when* to mark packes may be 
>>affected, and that additional flexibility in the marking at the 
>>internal
>>node may be potentially needed.   So in the very least this needs to
be
>>"kept in mind" even if the SIP (or application-related) deployment is 
>>taken out of the charter.

><Kwok_Start>
>Anna, I disagree with you on your points of:
>>"This specific model is likely to assume both lower levels of 
>>aggregation on the PCN internal links, but especially on a
per-ingress-
>>egress pair basis."

>There are no strict requirements that Application (SIP) based usage of 
>PCN must use lower levels of aggregation on the PCN internal links.
>Nor requirements that Application (SIP) based usage must use lower 
>levels of aggregation on a per-ingress-egress pair basis.
>I believe we should try to push the envelop of applicability as much as
>we can.

I fully agree that we should push the envelop of applicability as much
as we can. With respect to the aggregation level discussion it means
that we might want to look into how low hese levels of aggregation could
be.  I merely stated that for a SIP-based model one might expect a lower
degree of aggregation than that of an Intserv-over-diffserv model. I
think we are in agrrement that it would be beneficial if the WG looked
into the issue of how low the level of aggregation can be, and how it
affects the marking (if at all).

>We've indicated in our earlier work (for example, showing you our 
>simulation work so we can cover different aspects of the problem space
> the usage of lower levels of aggregation (at different parts of the
PCN >region) because there are deployment scenarios (with interested
users)
>that will benefit from such work.

Yes. That is right.  I do not think there is any disgreement on that.

>Further more, as you know, there are encouraging simulation results on 
>lower levels of aggregation on a per-ingress-egress pair basis.
>The degree of "how low" will be details that can be indicated in the
>work of the PCN (to-be)WG.

Yes. I agree with that.  In my opinion, perhaps the most important
aspect of the Sip/application based deployment model is the possible
limits of aggregation appropriate for that deployment model.  What I was
trying to say is that IF the decision is made to move the SIP-deployment
model to a later phase, the exploration of the limits of aggregation
appropriate for that deplyment model may nevertheless need to stay in
scope of the early work of the WG, as it may affect the router behavior
that needs to be standardized.

>On you point of "
>>"From the work available by now it seems relatively clear that if the
>>core marking is to accommodate this,  the decision on *when* to mark
>>packets may be affected, and that additional flexibility in the
marking
>>at the internal node may be potentially needed.   So in the very least

>>this needs to be "kept in mind" even if the SIP (or application-
>>related) deployment is taken out of the charter."

>IMHO, it should NOT be the goal of the WG to change the Standards Track
>work (the internal mode when to mark packets, marking syntax, the 
>marking semantics) between the different (re-chartering) phases of 
>the(to-be) WG. 

I do agree with that. I do not think I was agruing for changing the
router marking semantics between recharterings at all. In fact I was
arguing for exactly the opposite.  I was saying that a possible
difference in the aggregation level between different deployment models
*may* have impact on the marking semantics and potentially edge behavior
(my understanding is that the jury is out on this yet, although there
are good indications that both models may in fact use the same
semantics).  
Therefore this aspect (potential impact of appropriate level of
aggregation on the marking semantics) needs to be looked at early on, if
SIP/Application deployment  model is to be considered at any phase on
the work (now or later)at all. I was in fact arguing that it needs to be
looked at before rechartering.

But as to other aspects of the SIP/Application model (beyond the
aggregation level and its impact on the marking semantics and edge
behavior), I do not personally see a reason why they can not wait till
after rechartering.  

Anna

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---

From: "Kwok-Ho Chan" <[email-masked]>
Date: Thu, 30 Nov 2006 15:58:15 -0500

Anna:
Thank you for the agreements.
I agree with your agreements, hence the only response I have is
at the bottom of the E-Mail with <Kwok_Start> and <Kwok_End>.

Bottom line at the Top:
Keeping the Application/SIP Deployment Model document in the
first phase PCN Charter is beneficial to the WG.
Having it in the first phase PCN Charter will help rather then hurt the WG.
And there are accountable resource in the WG to get the work done.

-- Kwok --

>behavior), I do not personally see a reason why they can not wait till

<Kwok_Start>
The SIP/Application Deployment Model document will put the applicability
of this work in place.  It is always good to do this explicitly 
rather then implicitly.
This will provide clarity and openness to the work done by the WG.

The content for SIP/Application Deployment Model document is not really
new work for the people writing it.
The SIP/Application Deployment Model document will help the WG to understand
one possible environment of how PCN can be used.
Further more the SIP/Application Deployment Model document is there so
the simulation results (for the work we agreed to above) can be understood.

And there are already people doing this work that is beneficial to the WG.

And we should have more than one Deployment Model for PCN.  This will 
strengthen
the Standards Track part of the work we are doing.

Hence I propose to keep the SIP/Application Deployment Model document as part
of the first phase Charter of PCN.
<Kwok_End>