----- Forwarded message from Yee-Ting Li <Yee-Ting.Li@xxxxxxx> -----
Date: Mon, 21 Feb 2005 13:47:29 +0000
From: Yee-Ting Li <Yee-Ting.Li@xxxxxxx>
Subject: BicTCP Implementation Bug
To: linux-net@xxxxxxxxxxxxxxx, end2end-interest@xxxxxxxxxx,
linux-kernel@xxxxxxxxxxxxxxx
Cc: Douglas Leith <doug.leith@xxxxxxx>,
Richard Hughes-Jones <r.hughes-jones@xxxxxxxxx>,
Baruch Even <baruch@xxxxxxxxx>,
Les Cottrell <cottrell@xxxxxxxxxxxxxxxxx>, davem@xxxxxxxxxxxxx,
rhee@xxxxxxxx
X-Mailer: Apple Mail (2.619.2)
X-Mailing-List: linux-kernel@xxxxxxxxxxxxxxx
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;
-
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