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Re: Problems with the 3Com 3c905B NIC

On Sun, Nov 19, 2000 at 01:56:36PM -0600, Tilton wrote:
> "S.Salman Ahmed" wrote:
> > 
> > I got this OEM 3Com 3c905B card and added it to my system (ABIT-BH6,
> > Celeron 300A) which already has a generic 10/100 PCI NIC that has thus
> > far been working perfectly with Rogers@Home service.
> > 
> > BTW, the other NIC that works fine is detected by kernel as:
> > 
> > eth1: Macronix 98715 PMAC rev 37 at 0xe400, 00:80:C6:EE:A2:E3, IRQ 10.
> > 
> > I compiled in support for the card into the kernel that I am using,
> > 2.2.17 from sources with no patches, using the 3c59x.c driver. The card
> > is detected fine by the kernel at boot time as follows:
> > 
> > eth0: 3Com 3c905B Cyclone 100baseTx at 0xe800,  00:01:02:ca:90:fb, IRQ 11
> >   8K byte-wide RAM 5:3 Rx:Tx split, 10baseT interface.
> >   Enabling bus-master transmits and whole-frame receives.


I'm jumping into this thread in the middle. Please excuse me if this
has already been pointed out. Cable modem systems typically only allow
packets from one particular MAC address. In your case it would be the
one of the supplied NIC, 00:80:C6:EE:A2:E3. When you swapped the NIC,
the MAC address changed to 00:01:02:ca:90:fb. The fact the that the
LEDs are blinking on the cable modem means that the 3Com NIC is sending
packets to it. I think the packets are being denied by the the cable
companies router or gateway and thats why you don't get any response
back to the originating machine.

A simpler test for the 3Com NIC would be to use a crossover cable
between it and another known working NIC in another computer. If this
test should show the 3Com NIC to be working, then you could request
your cable company to change the allowed MAC address to that one.

Ron Golan

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