Bug#594676: linux-image-2.6-amd64: Files Download Pb with the atl1c module and my ReadyNAS
Package: linux-image-2.6-amd64
Version: 2.6.32+27~bpo50+1
Severity: normal
Hi,
I have an eeepc 1201n with debian stable lenny+backports. So I'm using
the kernel 2.6.32-bpo.5-amd64. The Ethernet controller is driven by
the module atl1c. I'm using firestarter as firewall.
I have a file transfer problem between my NAS (readyNAS Duo from
Netgear);
at first the symptoms:
- with firestarter installed (stopped or in use) I can connect my
eeepc to my NAS through FTP, CIFS or NFS. For example I can list or go
through my shares. But when I'm trying to download a file it is sooooo
slow. I get 12Ko in 10minutes...
- I can upload files from my eeepc to the NAS without problem with
"full speed".
- When I boot the eeepc under w7 I don't have any problem to download
files.
- I have two others computers on my LAN: a laptop with SID and the b44
module for the ethernet controller. With this laptop no problem at all
to download files from my NAS with firestarter installed. The other
one is a desktop station and I don't have any problem, too.
Now what I have done with the help of the debian.user.french list:
- the NAS has a MTU of 1500 (the software forces it). All the other
computers have an mtu of 1492. I don't choose it, my Netgear router
force it...When I set the mtu to 1500 on my eeepc with "ip link set
dev eth0 mtu 1500", then "ip route flush cache", I can dowload files
from my NAS without problem (firestarter installed and running). When
I set the both devices (eeepc and NAS) with a mtu to 1492, it doesn't
work at all.
- I have tested with the driver from realtek website and I get exactly
the same problem.
- I did capture with tcpdump. Guys of the debian.user.french mailing
list were surprised to see that lots of my packets were lost in my
"normal" configuration (firestarter installed, NAS mtu set to 1500 and
eeepc mtu set to 1492). And they see that my packets don't have a lot
of the normal TCP options (timestamp, selective ACK, window
scaling). So I check with sysctl if these options were enabled or not:
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_sack = 0
net.ipv4.tcp_window_scaling = 0
so they are disable on my "normal" configuration.
Then, I enable the options one by one and see that the
net.ipv4.tcp_timestamps option is a part of my problem:
with net.ipv4.tcp_timestamps = 0, eeepc_mtu=1492, NAS_mtu=1500 I get
problem to download files.
with net.ipv4.tcp_timestamps = 1, eeepc_mtu=1492, NAS_mtu=1500 I don't
have any problem to download files.
The program firestarter modifies the TCP options when it is
installed.
It seems there is a problem for the atl1c module with the timestamps
option disabled and different mtus. On my other laptop with the b44
module, a mtu of 1492 and firestarter I don't have this problem
between it and the NAS.
Sorry for this loooonnng bug report. I can provide tcpdump captures if
necessary.
Best regards,
Guillaume
-- System Information:
Debian Release: 5.0.5
APT prefers stable
APT policy: (987, 'stable'), (985, 'stable'), (500, 'lenny'), (195, 'unstable'), (95, 'experimental')
Architecture: amd64 (x86_64)
Kernel: Linux 2.6.32-bpo.5-amd64 (SMP w/4 CPU cores)
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8) (ignored: LC_ALL set to fr_FR.UTF-8)
Shell: /bin/sh linked to /bin/bash
Versions of packages linux-image-2.6-amd64 depends on:
ii linux-image-2.6.32-bpo 2.6.32-20~bpo50+1 Linux 2.6.32 for 64-bit PCs
linux-image-2.6-amd64 recommends no packages.
linux-image-2.6-amd64 suggests no packages.
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