>No! This is NOT a bug. It is known as Karn's rule, and it is absolutely
>requried by RFC 1122.
>The problem is that when you get an ACK for a retransmitted packet you
>have no information about the actual RTT of that packet, since the ack
>could be for any one of the multiply transmitted packets.
>If you start trying to reduce the RTO and the retransmission time really
>did get longer, then you will get yourself into a situation where
>you can never make a valid RTT measure again, and every packet will be
>retransmitted.
I know that. That's not the problem.
>The tiemr gets reset by the first good packet send/ack after a
>retransmission episode.
That is the problem. The retransmission episode will never end, and the
timer will never get reset. Try it. Open an ftp session, then drop the
route. When it starts retransmitting, put the route back, and run a
packet sniffer and watch the retransmit times.