Tcp Tuning for boardband ?

[Smoot Carl-Mitchell]

On Tue, 2007-11-20 at 10:05 +0100, Thilo Six wrote:

> use "window scaling" with caution.
> see:
> http://lwn.net/Articles/92727/

I agree.  I ran into this problem at a hotel's Internet access. The
provider had busted routers. It took me a while to diagnose the problem
and of course the provider's help desk people did not have a clue what
the problem was.

BTW, window scaling is on by default in the Linux networking stack.
Normally, this is fine, since the scaling is negotiated between the TCP
endpoints. If one side does not support it, it gets turned off. However,
if there are busted routers in the middle, then all bets are off.

Window scaling along with increasing the size of the TCP send and
receive buffers can help when utilizing high speed network pipes with
low packet loss and relatively high but consistent latencies. Unless you
are transferring large amounts of data, the default settings are
probably adequate. This is because TCP tunes itself to the available end
to end network bandwidth and network latency. Even if you have a 15
megabit connection, that does not mean you have 15 megabits of available
bandwidth to all remote destinations.
-- 
Smoot Carl-Mitchell
System/Network Architect
email: smoot at tic.com
cell: +1 602 421 9005
home: +1 480 922 7313