Re: tcp_window_scaling degrades performance

[Kasper Sandberg <lkml@metanurb.dk>]

hey, are you having some kind of hardware router?
bert hubert, helped me, and we found out my router was causing me the
problems, however, my problems were more severe, as my limit was 50kb/s

On Thu, 2004-07-15 at 17:09 +0200, Maciej Soltysiak wrote:
> Hi
> 
> I have been experiencied weird problems with network throughput
> lately and I after experimenting with /proc/sys/net/ipv4 knobs
> I found that when I have tcp_window_scaling 0 I can
> get throughput from a distant server of about 600kB/s (well, 200kB/s
> is fast enough)
> 
>    # links ftp://ftp.task.gda.pl/ls-lR
> 
> When I turn tcp_window_scaling to 1 the transfer starts with 600kB,
> then drops nicely to 20kB/s then starts growing again and reaches
> about 400kB/s
> 
> Anyway It works, but there are some hosts, with which I can't talk to
> faster than 800B/s !
> 
> This is a Debian SID with vanilla-2.6.7-bk20, but I am having these
> problems for a few weeks now.
> 
> It might be a TCP kernel issue, but I know that between me and the
> other hosts is a checkpoint fw-1 fp3, it may be the cause of problems,
> because, well, checkpoint is crazy.
> 
> Anyway, I can provide tcpdump, and tcptrace analysis of it and the
> state of sysctls if anyone would be willing to help me figure out
> what's going on.
> 
> Regards,
> Maciej
> 
> 
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