[MLB-WIRELESS] TCP Westwood

[Dan Flett]

Hi All,

During my presentation of OpenWRT at the General Meeting we had a discussion
about the various versions of the TCP protocol available.  TCP Westwood was
mentioned as being a good place to start with improving wireless links.  I'm
not sure what version of Westwood is compiled into OpenWRT WhiteRussian RC4
- but it's probably this patch:
http://buffer.antifork.org/westwood/westwood.html
Which is TCP Westwood Plus.

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

There was talk of another, even better TCP implementation for wireless but
nobody could remember what it was.  Could it have been TCP Jersey?
http://web.njit.edu/~ansari/papers/04JSAC_xu.pdf

The above paper has a good look comparisons between TCPs Reno, Vegas,
Westwood and Jersey - Jersey is slightly better than Westwood for wireless
links.  But I don't believe support for Jersey has been compiled into
OpenWRT.

Basically, these more advanced TCP implementations are better at recovering
from dropped or duplicate packets than standard TCP.  So on a lossy wireless
link, you're less likely to wait a long time for a web page to load.  TCP
Jersey and Westwood supposedly have better bandwidth "fairness" - that is,
they fairly share the available bandwidth between users of a network link.

Cheers,

Dan

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