Re: Network Performance Issues.

[Mike Bird <mgb-debian@yosemite.net>]

On Sunday 15 April 2007 08:20, Alan Chandler wrote:
> Now when I look at a similar exchange when I am using the gateway
> machine just as a hop and there is a machine behind the gateway I get a
> different pattern
>
> youtube->me http cont seq 4344 next seq 5792
> me->youtube tcp ack seq 5792
> youtube->me http cont seq 7240 next seq 8688
> me->youtube dup ack seq 5792
> youtube->me http cont seq 10136 next seq 11584
> me->youtube dup ack seq 5792
> youtube->me http cont seq 5790 next seq 7240
> me->youtube tcp ack seq 8688
> youtube->me http cont seq 8688 next seq 10136
>
>
> As you can see, in this case, it appears that some packets are being
> lost and have to repeated via a dup ack.

Check "cat cat /proc/sys/net/ipv4/conf/default/forwarding" is 1.
(Earlier kernels used /proc/sys/net/ipv4/ip_forward.)

Check your routing table with "ip route show".

Make sure "ip rule show" has only three lines, or check what the
additional lines are doing.

As a previous poster suggested, see how "iptables -L -nv" changes
during a download.  Also check "iptables -L -nv -t nat".

Try temporarily turning off your firewall, except for any rules needed
for NAT or masquerading.  (If you have any insecure services, stop them
before turning off your firewall.)

--Mike Bird