Force gigE NICs to operate at 100baseTX-FD.

Brian E. Seppanen seppy at chartermi.net
Tue Apr 13 10:09:00 CDT 2004


On Mon, 12 Apr 2004, Asim Zuberi wrote:

> Hi there --
>  
> I have the following configuration.....
>  
> Dell -- PowerEdge 650; OS: RedHat 9.0; Kernel: vmlinuz-2.4.20-30.9
> Network cards: Intel gigE cards 
>  
> The requirement is to operate the gigE network cards at 100Mbps
> Full-Duplex 
> with "no" auto-negotiation.
>  
> By default -- the NICs are getting configured 1000Mbps with
> auto-negotiation.
>  
> I did install the rpm package "e100-2.3.30-rh9-2.4.20-16.9.i386.rpm"
> from Intel
> to have the 100Mbps functionality....but the NICs are failing to operate
> at 100Mbps-full.
> Any suggestions?

> thanks!
> --Asim;
> 

I have to ask why would you be forcing the NIC to a slower speed?  Keep
this in mind:  when you force the NIC, and Switch both to the same speed
you will start to see CRC errors on the switch.  When you have them
autonegotiate you won't see CRC's.  I've seen this with E1000's, E100's,
3Com 3C509-B's. with Cisco 6509's, Cisco 2900's, Cisco 7609's.  I know
this shouldn't be the case, and I'm at a loss to explain why, but I have
observed this.  If someone could explain this I would appreciate it.  And
I have double checked and triple checked my configurations in all
instances on both ends, and I have found that forcing an Intel NIC on
Linux will cause CRC errors on the Cisco switch end.  Perhaps it's only a
problem with Cisco's.





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