Subject: (IPng 6543) Re: Host Fragmentation

From: Harald Tveit Alvestrand <[email-masked]>
Date: Mon, 28 Sep 1998 08:29:16 +0200

Big interface buffers (in excess of about 0.1 second queue time)
are harmful too; rather than causing sender TCPs to choke back on
transmission rate, they cause the sender TCP to increase its estimate
of round trip time.

IMNSHO: anyone who thinks that publicly accessible Internets can be
"properly engineered" hasn't lived in Europe - bandwidth starvation
has been with us since day 1, and is still a fact of life.

See http://www.nextel.no/kundesenter/nettinfo/statistikk/utland.html
for stats on one of the main Norwegian IP providers' US trunk.
No prizes for guessing its capacity....

I'd like to know what production environment you measured when you came
to the conclusion that most duplicate ACKs occur because of delayed packets,
not because of packet loss.

I'd also like to understand your comment:

>>  How many packets they lose depends on the traffic load and the number
>>  of TCP connections, and the presence of non-adaptive traffic.
>>  But the ONLY IP network that doesn't lose packets is one where the
>>  packet senders are not able to utilize the bandwidth.
>
>Damaged packets and topological instability aside, the comment is
>certainly not true.

Since TCP increases its transmission rate until it either fills the
recipient window or a packet is lost, you seem to be saying that in
some IP networks, all connections' transmission rate is limited by
the recipient window, not by the media capacity.
Is that what you are saying?

                         Harald T. Alvestrand

-- 
Harald Tveit Alvestrand, Maxware, Norway
[email-masked]

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