----- "Henrik NordstrÃm" <henrik@xxxxxxxxxxxxxxxxxxx> wrote: > tor 2010-09-30 klockan 13:24 +1000 skrev Paul Freeman: > > > However on further investigation, I don't think this is the case in > this > > instance. For some reason, the squid GET request to www.mhhe.com > (IP > > 12.26.55.139) takes a long time to be completed - approx. 2 minutes. > Some > > data is returned quickly but then there is a period where on my > squid server > > I see a TCP Previous Segment lost then squid server sending Dup ACKs > to > > www.mhhe.com and www.mhhe.com sending TCP Retransmissions for the > same > > segment. The Retransmission RTTs to ACK the one segment are at > 0.2,4,8,16,32 > > and 60 seconds. After that segment has finally been received, the > rest of > > the data is received OK. > > This smells like TCP window scaling issues in a firewall somewhere. > > Try as a test: > > echo 0 >/proc/sys/net/ipv4/tcp_window_scaling > > note that this is somewhat intrusive and reduces performance of TCP > in > general, but is an easy way of testing for the problem. > > Regards > Henrik I disabled tcp window scaling on both the squid box (linux 2.6.15), and our linux firewall (2.4.28), and saw no change in behaviour. What we're seeing certainly matches the description of tcp window scaling problems I've read about, so I was hopeful it might work. Thanks for the help.
