Bug#647866: Network: Packages over hub via bnc not received
Ben Hutchings wrote ..
> Please reply-to-all, not just to me.
>
> On Tue, Nov 08, 2011 at 08:30:39PM +0100, debian@achwg.dyndns.org wrote:
> [...]
> > > 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.
>
> My job revolves around networking hardware and I have seen many
> different kinds of networking failures, so please assume that I do
> know what I'm talking about.
Now I have tested a small setup with some different length of rg58 cable between two hubs.
Dockstar can not communicate with other network nodes, all other stations can see each other and routing works.
Arp request from dockstar can be seen in all network segments, arp replay from other computer can be seen on all
network segments.
Dockstar does not recognize any replays comming over rg58 (arp table is still "not complete")
Arp replays from machines connected via twisted pair cable on the same hub are recognized and communication works
(arp table has correct mac address).
> > > Maybe the original firmware enables higher amplification for received
> > > signals, so the network interface can properly decode weak signals.
If so is this configurable under debian or is that someting to change in kernel?
> > > What is the network driver and where is the source for the original
> > > firmware?
Because this is a small adapted linux the source code is not available I think (I do not have it).
Which network driver do you mean? The one which wokrs or the one which does not work?
This is the info of the debian which does not work:
root@debian:~# ethtool -i eth0
driver: mv643xx_eth
version: 1.4
firmware-version: N/A
bus-info: platform
On system Dockstar (with original software) this tool is not available and I can not adapt it.
> >
> >
> >
> > 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
>
> This is not a Debian kernel.
>
> [...]
> > If you need more / other inforamtion please tell tell me.
>
> Just tell me what I asked. What is the driver (you can probably
> find this out with 'ethtool -i eth0') and where is the source code?
> Don't tell me kernel.org; I'm quite sure this is modfiied by the
> manufacturer and I need to see what they did.
See comments above
>
> > >
> > > > 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.
>
> But then you have changed all the hardware, not just the distribution.
> You cannot reasonably infer from that that the important difference is
> the change of distribution.
As I have written before if I start dockstar with original firmware (so I change only the "distribution" and not the hardware)
routing over the hubs and the rg58 cable works.
Best regards
Hermann
>
> Ben.
>
> --
> Ben Hutchings
> We get into the habit of living before acquiring the habit of thinking.
> - Albert Camus
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