[WLANware] TCP Westwood

[Sven-Ola Tuecke]

Dan,

sorry. Send such a bunch of shit with the last post. Since the TCPW *is* 
compiled in Whiterussian, it is of couse in the Freifunk kernel already. 
Currently it is not activated by default - but I may change that for with 
the next version of that firmware. Proper place to activate is the 
/etc/sysctl.conf file. Just add a line, e.g. "edit /etc/sysctl.conf" and 
append (press [i]) a new line with "net.ipv4.tcp_westwood = 1", then [esc] 
[w] [q] [ret]. Then "reboot".

HTH Sven-Ola

""Dan Flett"" <conhoolio at hotmail.com> schrieb im Newsbeitrag 
news:BAY114-DAV17DB60D3F49FB1D9E791C1AFE60 at phx.gbl...
Hi all,

Has anyone tested TCP Westwood in their Mesh Network?

OpenWRT has TCP Westwood compiled in by default.  Is it also in Freifunk
Firmware?

From: http://193.204.59.68/mascolo/tcp%20westwood/tcpwestwood.htm

"TCP Westwood+ is a sender-side only modification of the TCP Reno protocol
stack that optimizes the performance of TCP congestion control over both
wireline and wireless networks. TCPW is based on end-to-end bandwidth
estimation to set congestion window and slow start threshold after a
congestion episode, that is, after three duplicate acknowledgments or a
timeout. The bandwidth is estimated by properly low-pass filtering the rate
of returning acknowledgment packets. The rationale of this strategy is
simple: in contrast with TCP Reno, which blindly halves the congestion
window after three duplicate ACKs, TCP Westwood+ adaptively sets a slow
start threshold and a congestion window which takes into account the
bandwidth used at the time congestion is experienced. TCP Westwood
significantly increases fairness wrt TCP (new) Reno in wired networks and
throughput over wireless links."

Perhaps TCP Westwood could be activated by default in the Freifunk Firmware?
It is backwards-compatible with previous TCP implementations.  Again, I'm
not sure if it is now included as a compile option in all the Linux v2.4
kernels, but there is a patch here:

http://buffer.antifork.org/westwood/westwood.html

You can activate it by issuing this command at the command line:
echo 1 > /proc/sys/net/ipv4/tcp_westwood

Cheers,

Dan

-------------
View my blog:
http://freenetjazz.blogspot.com
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