From owner-freebsd-questions Wed Nov 12 02:33:40 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id CAA23658 for questions-outgoing; Wed, 12 Nov 1997 02:33:40 -0800 (PST) (envelope-from owner-freebsd-questions) Received: from chouette.inria.fr (chouette.inria.fr [138.96.24.103]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id CAA23653 for ; Wed, 12 Nov 1997 02:33:32 -0800 (PST) (envelope-from Emmanuel.Duros@sophia.inria.fr) Received: by chouette.inria.fr (8.8.6/8.8.5) id LAA11000; Wed, 12 Nov 1997 11:33:27 +0100 (MET) Date: Wed, 12 Nov 1997 11:33:27 +0100 (MET) Message-Id: <199711121033.LAA11000@chouette.inria.fr> From: Emmanuel Duros To: questions@freebsd.org Subject: rfc1323, cannot make it work! CC: Emmanuel.Duros@sophia.inria.fr Reply-to: Emmanuel.Duros@sophia.inria.fr Sender: owner-freebsd-questions@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Hi, I have two FreeBSD stations (A & B) interconnected by a 3.4MBps broadcast satellite link. The RTT is about 330 ms. From A to B it takes 300ms and from B to A 30 ms. A runs FreeBSD 2.2.2-RELEASE and B runs 2.2.1-RELEASE. The maximum data rate I can get when I download a big file is 50 Kbyte/s. This is the maximum data rate I can reach with a 330ms RTT and a default tcp windows size of 16kbytes -> In one seconde the server can send 16*(1/0.330) = 50 Kbyte/s. Every Ack beeing generated by the client every 330 ms. According to rfc1323, increasing the size of the send and receive tcp buffers we can normally obtain a much better data rate. On both hosts A & B, I set net.inet.tcp.rfc1323 to 1 and net.inet.tcp.{recv|send}space with values ranging from 16384 to 65536. With a 65Kbyte window we should theoritically get close to 200Kbyte/s Using ftp and the netperf tool, I could not see any improvement as far as the data rate is concerned. Furthermore, whatever the value of rfc1323 (0 or 1) and even if I set the size of tcp buffer to 4096, I still get a 50 Kbyte data rate?!?!? I still have not understood why and I would appreciate any hint on this!!! Thanks Emmanuel