Subject: [Sipping] Re: draft-gurbani-sipping-connection-guidelines-01

From: Paul Kyzivat <[email-masked]>
Date: Thu, 17 Feb 2005 13:58:22 -0500

Thank you for doing this. It is a great start on an important subject! 
Somehow I missed the -00 version of this. I know this is a work in 
progress, so I don't want to nit pick on it. I have a few general points 
to make:

Normative Language

I find the way the normative language is used somewhat difficult to 
follow. For instance, there are many places where it is stated that if 
there is a matching entry in a cache then it MUST be used. Yet placing 
things in the cache is optional, and rules for declaring cache entries 
stale are also arbitrary. So the MUSTs seem futile.

Perhaps the goal here is to say that the behavior specified in this 
guideline is optional, but that those who claim to follow it must behave 
in a prescribed way. That may be helpful - it would be good to be clear 
about it. It would be even better if we could then find a way to signal 
when it is being followed.

Duplication of text:

There is much duplication of use case text describing behavior of UAC, 
UAS, and Proxy. I was left with the feeling that while this was very 
similar, there must be differences or else it would not have been 
repeated. Yet it is both long enough and similar enough that discovering 
the differences, if any, is hard. I was too lazy to bother. If there are 
common behaviors that are used in different use cases, it would be 
helpful to describe them once, then call them out in the different 
contexts in which they may be used, identifying any variations that apply.

Connections, or TCP Connections

The introductory stuff talks about both TCP and SCTP. Down in the cases 
there is only reference to making TCP connections. Its not clear whether 
these are supposed to apply to SCTP as well, via reader supplied 
analogies, or what. It would probably be sufficient to simply state that 
use cases for SCTP are TBD.

	Thanks,
	Paul

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---

From: "Vijay K. Gurbani" <[email-masked]>
Date: Fri, 18 Feb 2005 08:19:56 -0600

> Thank you for doing this. It is a great start on an important subject! 

Paul:

Thanks.  More inline.

> I know this is a work in progress, so I don't want to nit pick 
> on it. I have a few general points to make:
> 
> Normative Language
> 
> follow.
[...]
> about it. 

That is a good point; will do.

> It would be even better if we could then find a way to signal 

Ah, glad you bought this up.  An earlier work on which the I-D
is based did talk about signaling intent for some of what we
discuss.  We had presented that work at the 56th IETF
in March 2003.  At that IETF it was decided that a BCP would
be a good idea.

Now fast forward to today's timeline; as we were writing the
I-D, we did discuss whether we should suggest extensions to
the protocol.  But then again, if what we are producing is
a BCP, it cannot extend the protocol.  So in the end, we
decided that let's put our collective thoughts in the I-D and
get it to the WG with the hopes of hashing out whether we
need two documents: a BCP and a standards-track document
that discusses extensions.

> similar,
[...]

Right; the duplication has creeped in since before publishing
the I-D, we re-organized the I-D from its -00 version.  When
we rev it up, we will address these areas of duplication.

> use cases for SCTP are TBD.

Right; initially when we had presented the work at the 56th IETF
two years ago, TCP was the dominant connection protocol.  Since
then, of course, SCTP and TLS have become more prevelant.  As the
I-D progresses, we will need to decide if we want to focus only
on TCP or include all sorts of connection-oriented transports.
Some discussion around this in the WG will help solidify the
final shape of the I-D.

Thanks for your time on this and the comments.

- vijay
-- 
Vijay K. Gurbani  vkg@{lucent.com,research.bell-labs.com,acm.org}
Wireless Networks Group/Internet Software and Services
Lucent Technologies/Bell Labs Innovations, 2000 Lucent Lane, Rm 6G-440
Naperville, Illinois 60566     Voice: +1 630 224 0216