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Date:      Sun, 28 Nov 2004 16:59:52 +0100
From:      "Heinz Knocke" <knockefreebsd@o2.pl>
To:        <freebsd-net@freebsd.org>
Subject:   Why using timestamp based RTTM simplifies TCP sender?
Message-ID:  <001601c4d563$4de0e740$df5561d9@ALFA>

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Hi everybody!

While reading quite old but important RFC 1323 in chapter on RTT =
measurement based on timestamps I found an opinion that:=20

" A solution to these problems (rough RTT estimation) which actually =
simplifies the sender  substantially, is as follows: using TCP options, =
the sender places a timestamp in each data segment, and the receiver =
reflects these    timestamps back in ACK segments ..."

and
"Furthermore, the option is probably useful for all TCP's, since it =
simplifies the sender"

I really coldn't find many arguments, why adding another option will =
simplify sender's code. I think that no matter what it does, it cannot =
simplify because the stack needs to be backward compatible, so all =
previous solutions must stay. Maybe Van Jacobson thought about the =
situation when timestamp option becomes compulsory, making removal of =
some old bytes possible?=20

Could any of you guys  who are deep into TCP stack code could give me =
some hints?=20

Thanks in advance!
H.K



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