North American Network Operators Group

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Re: TCP and WAN issue

  • From: JAKO Andras
  • Date: Tue Mar 27 17:41:01 2007


> I have an east coast and west coast data center connected with a DS3. I 
> am running into issues with streaming data via TCP and was wondering 
> besides hardware acceleration, is there any options at increasing 
> throughput and maximizing the bandwidth? How can I overcome the TCP 
> stack limitations inherent in Windows (registry tweaks seem to not 
> functions too well)?

I don't know the RTT, but you should have at least 300 kByte buffers on 
the end hosts for a 60 ms RTT path to reach 40 Mbps TCP throughput. (This 
requires window scaling as well.) Is this what you were trying to tune on 
your Windows hosts?

Is your DS3 free of errors? Even a very low packet loss can degrade TCP 
performance badly.

You'll find a lot of useful information about TCP performance in the 
GEANT2 PERT Knowledge Base at