Best utilizing fat long pipes and large file transfer

Glen Turner gdt at gdt.id.au
Sun Jun 15 22:10:47 CDT 2008


goemon at anime.net wrote:

> Its actually not that hard on windows.

Don't make me laugh.  Instructions that start

"Enable TCP window scaling and time stamps by using the Registry Editor
to browse to location
  [HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Tcpip\Parameters]
and add the key
   Tcp1323Opts
with value
   3"

are "hard".  If you think otherwise, pick up the phone, pretend to
work for an ISP Help Desk, and walk someone who doesn't work in IT
through the changes.

Microsoft scatter the tuning information for Windows Xp all across
their website. Some of it is undocumented by Microsoft (and thus may
change without notice). The only saving grace is DrTCP, a third party
application which hides all of the registry detail (and potential for
disaster) under a nice GUI.

Then there's the deliberate nobbling of the TCP implementation,
such as the restriction to ten of connections to Windows Xp SP3.
Apparently you're meant to buy Windows Server if you are running
P2P applications :-)

Windows Vista is a vast improvement over Windows Xp (and I bet that
isn't said of many components of Vista). It has a autotuning TCP with
a 16MB buffer, which makes the defaults fine for ADSL and cable, but
still requires machines at universities to be altered.  Vista offers
an alternative TCP congestion control algorithm -- Compound TCP. Not
much is known of the performance attributes of this algorithm, mainly
because I.P claims prevented its incorporation into Linux, the corral
where most TCP algorithm shoot-outs take place.

-- 
  Glen Turner




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