Subject: Re: Header Stripping in Cellular

From: "Lars-Erik Jonsson" <[email-masked]>
Date: Fri, 22 Oct 1999 22:26:44 +0200

Hi Zoran!!

I have a couple of questions regarding what we are really talkning about
here.

- What is your definition of header stripping??

We all know what header compression is, because that is a term that has been
used for a long time and there are several protocols exemplifying what is
meant with the term.

Header Stripping on the other hand is something that has just been mentioned
a few times and never (what I have seen) together with a definition or any
kind of protocol proposal.

- What more do you remove in Stripping compared to Compression???

- Why do you think it is not possible to do ordinary, transparent header
compression efficiently enought??

- Are you considering TCP, UDP and/or UDP/RTP flows??

/Lars-Erik

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From: Vernon Schryver <[email-masked]>
Date: Fri, 22 Oct 1999 14:48:11 -0600 (MDT)

> From: Zoran Kostic <[email-masked]>

> ...
> I am afraid that  header stripping will almost inevitably be included
> at least as an option in standards that deal with cellular. And service
> providers will probably choose that option as a default operation mode.
>
> This is why:
> ...

Ok, in that case, the answer is still the obvious response to UDP-Lite.

> The questions we have to ask us are:
> ...

No, those are the wrong questions, because they assume both the nature of
the problem and the specific solution, and then trying to patch what is
fundamentally the wrong solution.

If radio bandwidth is so precious, then the obvious answer is to not use
IP on the air.  There is no law of nature or the IETF that requires or
even recommends that IP be used between the mobile user and the nearest
tower.  All that is needed is to move the bits between the phone and the
tower and terminate the TCP/IP or UDP/IP connections at the tower.  If
radio bandwidth is as precious as you say (I assume it is), then even the
telcos will eventually figure out that building nonstandard, not-really-
workable, complicated, buggy (at first at least), error prone sort-of-but-
not-really-TCP/IP-like protocols to run on the air is stupid.

It is all too likely that to get to that right solution, lots of
non-solutions will be deployed.  Still, in the end, if bandwidth
sufficiently error corrected for TCP and UDP is so precious (I think it
is), then the right kind solutions will be used.  To get (and so bill for)
the last bits of bandwidth, the pretend TCP/IP stuff will have to be
completely removed from the air.  For political reasons, you'll probably
call solution "TCP/IP," but it will have have as much to do with RFC 793,
RFC 1122, etc as GBit Ethernet has to do with CSMA/CD.

Just because a thesis advisor has heard of TCP/IP and thinks it would be
cool to get a few masters theses published about TCP/IP the IEEE
Transactions, or a pointy haired boss's boss's boss's boss's boss needs
to get "TCP/IP" into the division's report is no reason to do technically
silly things....well, maybe in the real world it is.

Vernon Schryver    [email-masked]

---

From: Zoran Kostic <[email-masked]>
Date: Tue, 26 Oct 1999 11:46:51 -0400 (EDT)

Thanks for inputs on header stripping
  for cellular. Since I come from the cellular 
  background, the discussion is very educational
  and it is important that I get the 
  message from the TCP community right.

  So this is my current understanding of 
  TCP/IP experts' views:

 * Header stripping is the wrong terminology -
   one should really talk only about header
   compression
 * Semantics of TCP/IP is all that matters, I can 
   do as unconventional header compression as I wish
   (something as ugly as carrying the TCP/IP header 
   info as a signaling part ot my RLP) - as long
   I do correct decompression.
 * Anything else can not be called TCP/IP

  Zoran