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From: Yee-Ting Li <Yee-Ting.Li@nuim.ie>
To: linux-net@vger.kernel.org, end2end-interest@postel.org,
	linux-kernel@vger.kernel.org
Cc: Douglas Leith <doug.leith@nuim.ie>,
	Richard Hughes-Jones <r.hughes-jones@man.ac.uk>,
	Baruch Even <baruch@ev-en.org>,
	Les Cottrell <cottrell@slac.stanford.edu>,
	davem@davemloft.net, rhee@ncsu.edu
Subject: BicTCP Implementation Bug
Date: Mon, 21 Feb 2005 13:47:29 +0000	[thread overview]
Message-ID: <fd9de42cb9cca9589da8a65bb6e719d5@may.ie> (raw)

Hi,

We have discovered a serious implementation bug in BicTCP on the Linux 
kernels. Note that because BicTCP is ON by default, this affects all 
users of kernel versions 2.6.8 and above.

For further details please see: 
http://www.hamilton.ie/net/bic-fix/Linux%20BicTCP.pdf

and the patch is:

Index: linux-2.6.10/include/net/tcp.h
===================================================================
--- linux-2.6.10.orig/include/net/tcp.h Fri Dec 24 21:34:00 2004
+++ linux-2.6.10/include/net/tcp.h      Thu Feb 17 14:13:14 2005
@@ -1280,8 +1280,7 @@
                 if (sysctl_tcp_bic_fast_convergence &&
                     tp->snd_cwnd < tp->bictcp.last_max_cwnd)
                         tp->bictcp.last_max_cwnd
-                               = (tp->snd_cwnd * 
(2*BICTCP_1_OVER_BETA-1))
-                               / (BICTCP_1_OVER_BETA/2);
+                           = tp->snd_cwnd - ( tp->snd_cwnd / 
(BICTCP_1_OVER_BETA*2) );
                 else
                         tp->bictcp.last_max_cwnd = tp->snd_cwnd;


             reply	other threads:[~2005-02-21 13:48 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-02-21 13:47 Yee-Ting Li [this message]
2005-02-21 15:50 ` BicTCP Implementation Bug Stephen Hemminger
2005-02-21 16:15   ` Yee-Ting Li
2005-02-21 17:06 ` Gene Heskett

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