Possible network issue in 2.6.8.1

Possible network issue in 2.6.8.1

[Joris Neujens]

Hello,

We've got a weird problem at our university network.  Since we upgraded to
kernel 2.6.8 our download rate never gets higher than 10kB/sec.  Upload
remains at original rate.  This problem does not occur with previous
kernels (works fine again after downgrading to 2.6.7, without changing
anything at the kernel config).

There are no speed issues when transfering on the LAN, only when
downloading something from the internet

We have ruled out the following:
Network source is slow (we were testing with the same FTP server all the
time, from which we normally download at 10MB/sec)
We tested with 3 different systems and network cards, and they all have
the same problem, and only with kernel 2.6.8

any thoughts?

Regards,

Joris Neujens
Lennart Yseboodt
Michael De Nil

Re: Possible network issue in 2.6.8.1

[Alan Cox]

On Maw, 2004-09-07 at 14:55, Joris Neujens wrote:
> We have ruled out the following:
> Network source is slow (we were testing with the same FTP server all the
> time, from which we normally download at 10MB/sec)
> We tested with 3 different systems and network cards, and they all have
> the same problem, and only with kernel 2.6.8
> 
> any thoughts?

See the list archive, or the lwn article on broken routers mangling TCP
window size negotiation. The lwn article has a nice discussion as well
as workarounds if you need them.

Re: Possible network issue in 2.6.8.1

[Paolo Ornati]

On Tuesday 07 September 2004 15:55, Joris Neujens wrote:
> Hello,
> 
> We've got a weird problem at our university network.  Since we upgraded to
> kernel 2.6.8 our download rate never gets higher than 10kB/sec.  Upload
> remains at original rate.  This problem does not occur with previous
> kernels (works fine again after downgrading to 2.6.7, without changing
> anything at the kernel config).
> 
> There are no speed issues when transfering on the LAN, only when
> downloading something from the internet
> 
> We have ruled out the following:
> Network source is slow (we were testing with the same FTP server all the
> time, from which we normally download at 10MB/sec)
> We tested with 3 different systems and network cards, and they all have
> the same problem, and only with kernel 2.6.8
> 
> any thoughts?

http://lwn.net/Articles/92727/

-- 
	Paolo Ornati
	Gentoo Linux (kernel 2.6.8-gentoo-r3)

Re: Possible network issue in 2.6.8.1

[Lee Revell]

On Tue, 2004-09-07 at 09:55, Joris Neujens wrote:
> Hello,
> 
> We've got a weird problem at our university network.  Since we upgraded to
> kernel 2.6.8 our download rate never gets higher than 10kB/sec.  Upload
> remains at original rate.  This problem does not occur with previous
> kernels (works fine again after downgrading to 2.6.7, without changing
> anything at the kernel config).
> 

This is quickly becoming a FAQ:

http://lwn.net/Articles/92727/

Short answer: you have a broken router.

Lee