Subject: TCP timestamping inquiry

From: Alhussein Abouzeid <[email-masked]>
Date: Thu, 22 Mar 2001 18:40:41 -0800 (PST)

Hi all,

Anyone has any pointers to info/measurements regarding noticeable
performance issues with/without TCP time-stamping or any
deployment issues? specifically, I am interested in any clear negative,
positive or 'no effect' results regarding its use in the Internet,
satellite or wireless/ad-hoc.

Thanks in advance,

Hussein.

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From: Mark Allman <[email-masked]>
Date: Fri, 23 Mar 2001 09:32:36 -0500

> deployment issues? specifically, I am interested in any clear
> negative, positive or 'no effect' results regarding its use in the
> Internet, satellite or wireless/ad-hoc.

Vern Paxson and I found that using timestamps with the current RTO
algorithm doesn't really buy you much.  See:

    Mark Allman, Vern Paxson.  On Estimating End-to-End Network Path
    Properties.  ACM SIGCOMM, September 1999. 
    http://roland.grc.nasa.gov/~mallman/papers/estimation.ps

(However, note that timestamps are needed for PAWS if your sending
rate is quite high.)

As for deployment, I have some measurements on the use of timestamps
"in the wild" in the following paper:

    Mark Allman.  A Web Server's View of the Transport Layer.  ACM
    Computer Communication Review, 30(5), October 2000. 
    http://roland.grc.nasa.gov/~mallman/papers/webobs-ccr.ps

allman

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Mark Allman -- BBN/NASA GRC -- http://roland.grc.nasa.gov/~mallman/