> When the initial RTT estimate is too low then there will be no segments going
> without any retransmits. On a connection with no timestamps all RTT estimates
> retransmitted packets are ignored due to Karn's rule. Unfortunately this
> means that
> when the initial RTT is too low it'll never get a new estimate, because all
> packets that arrive at the other end were already retransmitted. The
> gets lots of faulty retransmits forever. Oops.
No oops. This RFC statement simply means that connections with rtt>3sec
are not going to work with TCP.
Partially, it was solved old days in Linux (specially for ultra-slow AX.25
links) with static rtt option on routes.
> Any suggestions on that? Any other ideas?
Right idea, in theory. But Andi, where did you find connections with rtt>3sec?
The worst link, which I ever saw was faulty 2400baud line and it had
rtt a bit lower. 8)