On 11/18/16 at 09:20P, Michael Tuexen wrote: > Dear all, > > in the last telco we discussed the behaviour when that last N packets are > dropped. > It was mentioned that multiple retransmission timers where used to recover. > > I wrote a packetdrill script which > * Get the cwnd to 30 segments > * Sends 30 segments, which all get lost > * Observe how the 30 dropped segments are retransmitted. > > It uses only a single timeout as one would expect. > So this script does NOT reproduce the problem, but I'm attaching it such that > you can see how the stack behaves. > Tested with FreeBSD head r308802.
Thanks for testing. https://reviews.freebsd.org/D8556 was the issue detecting a valid RTO as bad and resetting snd_nxt to snd_max (instead of snd_una as done by valid RTO) causing us to not trigger retransmit of missed packets but wait for RTO for all of lost packets. Cheers, Hiren
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