Subject: Re: [Ieprep] implementation issues (fwd)

From: Ken Carlberg <[email-masked]>
Date: Sun, 10 Feb 2002 11:41:51 +0000

> This question is regarding implementaion issues
> regarding IEPS.  It seems to me that implementing IEPS
> requires remodeling many protocols at various levels
> in the TCP/IP stack . 

ouch.  the above observation can be a bit dangerous because it takes
on too much.  Its ok if one starts from scratch in thinking how one
addresses support of emergency-related flows.  But, its been argued
that one needs a problem or a set of requirements constituting an
objective (a problem to be resolved) before assuming the extent of
"remodeling many protocols".  (and of course, some may argue nothing
needs to be done).

on the other side of the spectrum, a per-application, per-transport, 
per-network, and any combination thereof, examination would also seem 
to be quite a challenge and may be to large a problem space.

i think classifying groups of applications along the lines of tcp-based 
(short or long lived), transaction oriented, and udp-based interactive 
is a bit easier.  it may not be perfect, and examples of exceptions may 
slip through, but it makes the problem space easier.

> The very simple case of
> modifying the DS codepoint (to include priority) will
> require changes in many TCP/IP protocols. 

why would it require changes?  

outside of that.  some folks contend that the existing code points can 
be used to satisfy emergency communications (at least with respect to 
the specific problem of IP telephony).  see the Baker draft and Pierce
draft, which include an example approach.

http://search.ietf.org/internet-drafts/draft-baker-ieps-requirements-00.txt
http://search.ietf.org/internet-drafts/draft-pierce-sipping-assured-service
-00.txt

> Can't it be
> possible to work on the existing protocol standard
> with minimum modifications ( maybe make changes at one
> particular layer )?

did you have a layer in mind?

it may be possible, and i certainly wouldn't want to discourage work to 
try and accomplish it.  but you may want to ask yourself if the layer 
(or sub-layer) you choose applies to the types of applications and their 
underlying transport protocols can be supported.

-ken

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