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Date: Fri, 4 Mar 2005 15:30:04 -0800 (PST)
From: Kan Cai <kcai@cs.ubc.ca>
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cc: Brad Penoff <penoff@cs.ubc.ca>
Subject: FreeBSD 4.11-RELEASE & SACK
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Greetings,

I posted this question on freebsd-question list yesterday, but no replies. 
So I am just trying my luck here. Thanks in advance.

I've installed the standard FreeBSD 4.11-RELEASE and have realized that the 
sysctl option for enabling SACK in TCP is not available (net.inet.tcp.do_sack). 
Additionally, the tcp_sack.c file is not in the /usr/src/sys/netinet so I'm 
guessing this indicates that I need a patch. Hoping to be able to use SACK in 
FreeBSD 4.11-RELEASE, I wanted to ask :

1) Is my guess correct (Do I need a patch)?  Or is my kernel configuration file 
missing an option?
2) Assuming I need a patch, what patch is generally recommended for using SACK 
under TCP in FreeBSD 4.11-RELEASE?

Any help would be most appreciated.  Thanks,

ken