Subject: [Diffserv] Model draft - open issues list

From: Andrew Smith <[email-masked]>
Date: Tue, 05 Dec 2000 12:10:56 -0800

I think there are 3 open issues (2 technical, 1 editorial) with the current
draft (I've put names at the end of each description for people who I know care
about this issue). I'll offer some proposals for 1 and 2 in separate messages.

1. Section 7.1.3 Model for Algorithmic Droppers (Andrew, Grenville, Walter)

The current figure 5 was put in at the last minute for draft-04 but I don't 
think it is as intuitive as the one I'd earlier proposed. In particular, the 
current figure 5 shows an AD as something that sits on the side of a main 
datapath performing its job by influencing a queue. I prefer the formulation 
that places an AD in-line, either before or after a queue: keeping it as is 
leads to quite a few awkward fixups and explanations throughout the document 
(this is the only case where we have an element "on the side of" a datapath so 
there are a bunch of "exception" cases to describe it).

2. Section 3.2 Sharing of elements amongst multiple interfaces (Bob, Walter)

Bob Moore has made a good point: right now the model describes everything that 
happens to a packet as it arrives on ingress to *an* interface, then it goes 
through a routing core, then it describes what happens on egress from *an* 
interface. The problem is that there are very valid scenarios (and 
implementation architectures too, although that's not really our problem here) 
where you want traffic streams from multiple ingress interfaces to receive 
shared processing before they get to the switch fabric. Ditto for a stream on 
egress to receive some diffserv processing before being split out to its final 
egress interface. This is a fairly fundamental ommission and I don't think it 
can be tackled by hand-waving. So we should choose whether to support it 
explicitly or not.

3. Section 11 - dangling references to in-progress drafts.

I propose to eliminate these if I cannot get a promise from some other WG chair 
that they will be completed in the same time-frame as this draft (i.e. 
submission to IESG within next 3-4 weeks). (John W, Eric, Brian, Kathie, Ed, Joel)

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