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Date:      Thu, 25 Jan 2001 09:27:19 +0900
From:      Tatsuhiko Terai <genuine@ma4.justnet.ne.jp>
To:        Garrett Wollman <wollman@khavrinen.lcs.mit.edu>
Cc:        freebsd-net@freebsd.org
Subject:   Re: estimation of RTT,RTO from tcpcb parameter
Message-ID:  <3A6F72E71D6.7B48GENUINE@ma4.justnet.ne.jp>
In-Reply-To: <200101250009.TAA73303@khavrinen.lcs.mit.edu>
References:  <3A6F67132EE.7B47GENUINE@ma4.justnet.ne.jp> <200101250009.TAA73303@khavrinen.lcs.mit.edu>

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Thanks for your advise.

> No.  Please take a look at W. Richard Stevens' _TCP/IP Illustrated_
> series, particularly volume 2.
> 
I'll try.

> Nothing inside the kernel is measured in milliseconds.  TCP parameters
> are measured in timer ticks, the length of which depends on which
> version of FreeBSD you are running and (potentially) on what hardware
> platform.

By the way, my running machine is P-III 1GHz with i820 chip and
FreeBSD-4.0-RELEASE.
Is the length of time tick for this plathome invert of 1GHz?
(1/10^-9 [s])? or 10 [ms] (I think it is the time ticks for FreeBSD)?

RTT = (tp)->t_srtt >> (TCP_RTT_SHIFT - TCP_DELTA_SHIFT) shows 
sometimes rapidly increase to 40 between ti0 gigabit link.
I think 40 * 10 [ms] is too longer for rtt, so I confused..

If there is some information, would you please like toteach ?

Thanks-


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