Subject: transparent tcp improvements

From: "Karl Jonas" <[email-masked]>
Date: Mon, 15 Apr 2002 10:10:35 +0200

Dear Experts,

I browsed through your mailing list archive, looked at a couple
of referenced docs, looking for the following solution to the
long-delay problem:

having a mobile device attached to a long-delay wireless link,
I would like to improve tcp's performance by sending early ACKs
from a box at the 'end' of the terrestrial network towards the
tcp sender in the terrestrial network:

mobile -- (long delay wireless link) -- tcp box -- (terrestrial nw) --
sender

The idea is that tcp's slow start / congestion avoidance mechanism
will handle the situation in the terrestrial nw correctly, and
transmission will not suffer from the long delay link.

The 'tcp box' must monitor tcp sesssions, generate acks towards the
sender (possibly drop acks from the mobile?), and of course buffer
tcp data that it has ack'ed to the sender, but which has not been
ack'ed by the mobile yet.

Since this is a very simple idea, I am sure that it has been
implemented and evaluated.

Please send me any reference to such an approach (I could not find one
yet).

Note that I am not interested in split-tcp, snoop, i-tcp or similar
approaches that are non-transparent to the sender/receiver, or that
need a modification on the mobile terminal side of the wireless link.

Thanks for your help (please reply (also) to my address [email-masked])

Karl

--
Prof. Dr. Karl Jonas            EMail: [email-masked]

University of Applied Science   FhG FOKUS CC SATCom
Grantham-Allee 20               Schloss Birlinghoven
53757 Sankt Augustin            D-53754 Sankt Augustin

Tel: +49 (0)2241 865244         +49 (0)2241 141599
Fax:                            +49 (0)2241 141050
WWW:                            www.gmd.de/people/Karl.Jonas/

---

From: Mike Jagdis <[email-masked]>
Date: Mon, 15 Apr 2002 10:06:16 +0100

> tcp sender in the terrestrial network:

You mean ACK data befoe you've actually received it? Isn't that
a little dodgy unless you have some other underlying protocol
guaranteeing a perfect link?

Anyway, it sounds very like Stefan Savage's[1] work on TCP with
misbehaving receivers[2] (aka "Daytona TCP")

				Mike

[1] http://www.cs.washington.edu/homes/savage/
[2] http://www.cs.washington.edu/homes/savage/papers/CCR99.pdf

---

From: David Carek <[email-masked]>
Date: Mon, 15 Apr 2002 09:44:40 -0400

Karl Jonas wrote:
...
> implemented and evaluated.
...

Mentat has a product that does this.  This isn't an endorsement of the 
product, as I've never used it, but it seems to be popular.  It does 
create split sessions (which you said you didn't want) but it is 
transparent to the sender and and receiver.  Not sure how you could 
realistically do this without splitting the connections.  There have 
also been efforts to use TCP directly but you would have to run a 
special TCP stack on both the sender and receiver.  (see rfc2760 Allman, 
et al.)

mentat is at
http://www.mentat.com/skyx/skyx-gateway.html

also try
http://www.flashnetworks.com/Product.asp?table=Providers
http://www.tachyon.net/Technology.html
http://www.viasat.com
http://www.tellique.de

---

From: Joseph Ishac <[email-masked]>
Date: Mon, 15 Apr 2002 09:49:25 -0400

> ack'ed by the mobile yet.

This is "TCP Spoofing" as described in RFC 3135 on PEP's.  Also, a Milcom paper
on the subject http://roland.grc.nasa.gov/~jishac/papers/2001/TCP_Spoofing.pdf
(please excuse the shameless self plug :)

I strongly suggest reading RFC 3135 if you have not done so already.

- Joseph