Re: How to Quicken TCP Re-transmission?

On Mon, 22 May 2006 19:51:33 +0800
mag@xxxxxxxxx wrote:

Hi,
I want to transmit data between host A and host B. The link
between these two hosts is really bad: PING reports 30% packet loss
and about 60 ms return delay. This means if timed out for 1 second,
the data must have been lost.
I keep "net.inet.tcp.rexmit_min" and "net.inet.tcp.rexmit_slop"
untouched. But TCPDUMP tells me that if some data are lost,
re-transmission will be done 64 seconds after last transmission!
How to quicken TCP re-transmission?
How to tune "net.inet.tcp.rexmit_min" and
"net.inet.tcp.rexmit_slop"?

You can take a look at SCPS - http://www.scps.org/
Their protocol is used on lossy links with big latency and
packet loss (such as satellites) and overcomes shortcomings of TCP.
It works with divert mechanism of FreeBSD and I ported the
tap device part as well to both NetBSD / FreeBSD (experimental).

Cheers,
Marcin.
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