3C905B - 3c59x

Steven Ringwald SRingwald at telesmartnetworks.com
Mon Dec 19 02:44:59 UTC 2005


On Sun, 2005-12-18 at 20:23 -0500, Jeffrey Ross wrote:
> I have an older PIII system loaded with Fedora Core 4.  I have been 
> trying unsuccessfully to enable the ethernet interface as 100Mb Full 
> duplex and have had no luck at doing so. 
> 
> What I have done so far:
> 
> 1) Let autonegotiate run its course, I get 10Mb half duplex
> 2) run ethtool -s eth0 speed 100 duplex full.  still 10Mb half duplex 
> even though ethtool tells me otherwise
> 3) set the switch port to 100Mb Full duplex and restart the machine, no 
> connectivity at all
> 4) modified the /etc/modprobe.conf file to read the following: alias 
> eth0 3c59x options=0x204 and ran depmod -ae reloaded but still 10Mb half 
> duplex.
> 
> What I have noticed is after the machine completes its POST I immediate 
> have a link on the ethernet port at 10meg half duplex.  Attached is the 
> output from lspci -v
> 
> The interface works reliably at 10meg half duplex, suggestions?
> 
> thanks, Jeff
> 
> 00:0e.0 Ethernet controller: 3Com Corporation 3c905C-TX/TX-M [Tornado] 
> (rev 6c)
>         Subsystem: 3Com Corporation 3C905C-TX Fast Etherlink for PC 
> Management NIC
>         Flags: bus master, medium devsel, latency 80, IRQ 11
>         I/O ports at 1080 [size=128]
>         Memory at f4000000 (32-bit, non-prefetchable) [size=128]
>         [virtual] Expansion ROM at 20000000 [disabled] [size=128K]
>         Capabilities: [dc] Power Management version 2
> 

Have you tried plugging another machine with a different ethernet card
type into that port to see that it is in fact negotiating 100-Full? I
have had this happen to me, and it turned out that the switch port was
set to 10-Half, because the previous cabling to that port was only
reliable to 10-Half. The next thing I would try is trying to hook the
machine up to the switch with something like a Cat-5E cable (rated to
gigE, and seeing if it is perhaps the cable that is doing it). If you
can get the other card to do 100mb, and the cabling doesn't change
anything, then I would agree that it is something with the card. Do you
have any other 905s that you could try? It might be a hardware problem
on that particular card. If at least two 905s behave the same way, and
the other card works, then I would try the 905 in another machine
(perhaps a windows box) to see if it has something to do with the
driver. I use several 905s in my networks at home and at work, and
haven't had any problems with them in P3s and running FC3 and FC4, out
of the box. 

There is a tool, BTW, called mii-tool that will let you muck with the
autoneg settings of the card and media type without having to set the
option line, or rebooting/reinserting the module. That might help you a
bit in your debugging. 

Cheers!
Steve




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