On Mon, 2017-09-18 at 13:14 -0700, hiren panchasara wrote: > Hi all, I am trying to disable rack to see 3dupacks in action during > loss-detection but based on the pcap, I see that it's still trigger > loss-recovery on the first SACK (as if RACK is still enabled/active). > > Here is what I did to disable rack: > net.ipv4.tcp_recovery = 0 > > I've also disabled metrics: > net.ipv4.tcp_no_metrics_save = 1 > And also flushed existing entries with 'ip tcp_metrics flush' just to be > on a safer side. > > Not really relevant here but I've also switched to reno. > > I am on: 4.10.0-33-generic > pcap: https://transfer.sh/mfoiN/reno_no_rack.pcap > > What am I missing? I can provide any additional info. > > Cheers, > Hiren
A single SACK can contains enough information to trigger a retransmit. If you absolutely want to see the old 3 dupack in action, you also want to disable SACK.
