Re: Excessive TCP retransmits over lossless, high latency link

kuznet
2001-09-01T18:08:47Z

Hello!

> The interesting thing is that there isn't any evidence of packet loss.

Why did you disable bith sacks and timestamps? Exactly to get
maximal damage from long delay link?

> Is there some /proc/sys setting to fix this, a kernel patch, or is it
> perhaps fixed in a newer kernel already?

No patches to block send required ACKs exist of course. :-)

All the problem is at sender, it mispredicts rtt.
What OS is sender? If it is linux too, try to use default configuration
not playing with /proc/sys/net/tcp_*, especially with timestamps
and sacks and the situation should rectify.

Also, please, send full (binary!) tcpdump from SYN and to FIN.
Andi says right thing, but I am still puzzled why rtt is miscalculated
it should be estimated correctly.

Well, and if sender is not linux... no ideas.

Alexey