Date: Sat, 16 May 1998 12:49:03 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: hackers@FreeBSD.ORG Subject: bad behaviour in slow start Message-ID: <199805161049.MAA04082@labinfo.iet.unipi.it>
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I noticed this a couple of years ago, but the problem appears to be
still there in -stable.
In tcp_input.c there is an "optimization" that disable slow_start
on local networks. This was introduced in version 1.11 of the file.
The relevant lines are:
/*
* Don't force slow-start on local network.
*/
if (!in_localaddr(inp->inp_faddr))
tp->snd_cwnd = mss;
I think this is in violation of good TCP practices, and should be at
the very least made optional, controlled by a sysctl variable which
defaults to off:
static int no_slowstart_on_local_net = 0;
SYSCTL_INT(_net_inet_tcp, OID_AUTO, no_slowstart_on_local_net, CTLFLAG_RW,
&no_slowstart_on_local_net, 0, "");
...
if (!no_slowstart_on_local_net || !in_localaddr(inp->inp_faddr))
tp->snd_cwnd = mss;
comments ?
luigi
-----------------------------+--------------------------------------
Luigi Rizzo | Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it | Universita' di Pisa
tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/
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