Hello,
Thank you for your fast answer and support.
Please see my answers /remarks included below.
Ben Hutchings wrote ..
> On Mon, 2011-11-07 at 01:48 +0100, debian wrote:
> > Package: linux-base
> > Version: 2.6.32-38
> > Severity: normal
> >
> > Hello,
> > sorry for this unspecific bug report / question:
> >
> > After installing debian squeeze the networking does not work in the
> > following situation:
> >
> > Situation:
> > I have a debian patched "Dockstar" (embedded system dockingstation NAS)
> > box which is connected to a hub.
> > This hub is connected via bnc-cable (coax) to another hub on which a
> > linux box (Suse) is connected (router to internet).
> >
> > If Dockstar tries to connect to internet it "arps" for the gateway MAC
> > (arp-request is seen on all netork parts with wireshark).
> > The answer (arp-replay) is also seen an all network part.
> >
> > The arp table on the dockstar will not be updated by this communication
> > ("arp -n" shows always "(incomplete)" for HWaddress) and continoues arp
> > request can be seen.
> > Any network packet directed to the dockstar can be seen on all parts of
> > the network (this were seen with whireshark) but in debian there is
> > nothing received.
> >
> > If I connect the debian-dockstar and the linuxbox over the same hub
> > without bnc the communication is OK!
> >
> > It seems NOT to be a hardware problem of the dockstar, because with
> > original firmware (also a linux) connection over bnc to internet works fine.
> > I found a information on internet about problem with older hub/network
> > hardware which inject some sort of incorrect crc errors
> >
> > http://www.plugcomputer.org/plugforum/index.php?topic=5772.msg18770#msg18770
> >
> > Is there a way to configure debian linux to ignore such crc errors?
>
> CRC checking is a hardware feature and should not be disabled. If you
> were to do so, you would find that the contents of the received packets
> are junk.
>
> I would guess that the problem is related to signal levels. Because you
> are using hubs, signals have to travel all the way from one computer to
> the other, whereas a switch or router will receive and re-transmit each
> packet. When you remove the coax cable you are shortening the distance
> between the computers and so the received signal is stronger and there
> are fewer errors.
>
So this could be tested with a short cable (but >0,5m) between two hubs.
I will try, but I do not think that this is the problem.
> Maybe the original firmware enables higher amplification for received
> signals, so the network interface can properly decode weak signals.
> What is the network driver and where is the source for the original
> firmware?
Following infos were catched from dockstar device.
With that version the network works well.
It seems to be debian also.
Pogoplug:~$ cat /proc/version
Linux version 2.6.22.18 (bdietrich@brad-ux) (gcc version 4.2.1) #57 Mon Aug 31
16:31:01 PDT 2009
Pogoplug:~$ uname -a
Linux Pogoplug 2.6.22.18 #57 Mon Aug 31 16:31:01 PDT 2009 armv5tejl unknown
Pogoplug:$ cat /proc/cpuinfo
Processor : ARM926EJ-S rev 1 (v5l)
BogoMIPS : 1192.75
Features : swp half thumb fastmult edsp
CPU implementer : 0x56
CPU architecture: 5TE
CPU variant : 0x2
CPU part : 0x131
CPU revision : 1
Cache type : write-back
Cache clean : cp15 c7 ops
Cache lockdown : format C
Cache format : Harvard
I size : 16384
I assoc : 4
I line length : 32
I sets : 128
D size : 16384
D assoc : 4
D line length : 32
D sets : 128
Hardware : Feroceon-KW
Revision : 0000
Serial : 0000000000000000
If you need more / other inforamtion please tell tell me.
>
> > What I do not understand is that all other linux boxes do not have this
> > problem.
>
> Because other people do not use 10BASE-2 and hubs!
That is not be the point.
I use this network for years with some linux and windows boxes.
There must be a difference between Suse and Debian squeeze.
If I use another linux computer in substitute for the dockstar at the same
network point
the problem does not appear.
>
> > Is there a relevant change on kernel module concerning networking?
>
> No.
>
> Ben.
>
> --
> Ben Hutchings
> You can't have everything. Where would you put it?
