[svlug] Reprise: Adjusting retransmission parameters
nickell at parc.xerox.com
Tue Feb 20 06:22:09 PST 2001
Jeffrey Siegal wrote:
> There is really no way to get "good" performance from TCP with packet
> loss rates of 50%. If you can maintain connectivity at all, you are
> doing well. If your packet loss rate is really that bad, you will need
> to get Sprint to fix it, or just suffer.
I agree with you. I don't expect to get anything done when the packet
losses are that high. However, I'm currently stymied even when the
losses are 1-3% as my X window will stop responding to mouse click for
15 seconds or a minute. It is this latter that I'd like to fix.
> Once you can reduce packet loss to a reasonable level, you'll probably
> get better performance over a high bandwidth, high latency connection
> when talking to systems that support the LFN extensions from RFC 1072.
> Linux does, but other systems don't.
I don't have control over the system that I'm connecting to. That's why
I was trying to learn about things that I can change inside my Linux box
to improve the situation.
> My guess is that Sprint's connection is asymmetric.
I would agree. Mostly, I'm guessing there are packet collisions on the
uplink, and none on the downlink.
> The performance you
> can get out of an asymmetric connection is limited by fundamental design
> weaknesses in TCP in dealing with such connections. There have been
> some improvements proposed, but not widely implemented. For more info
> on this, see
In the meantime, is there no short-term relief?
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