Cisco 837 ethernet0 half-duplex

Hi, all,
When I plug in a Cisco837 router into the swich, it gives me a
warning message: CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on
Ethe
rnet0 (not half duplex).

When I do a "sh interface ethernet0", it shows: "Full-duplex,
10Mb/s".

The IOS is: 12.3(8). Is there anyway to change it to half duplex?

Thanks.

 

what switch are you plugging the router into and how is the port
configured ?

 

find out if the switch is capable of 100-full or 10-full and set it
accordingly

otherwise on the 837 try

ethernet 0
speed 10
duplex half
exit

 

I had the same problem on an 837 and 2950 switch. IIRC, setting the
duplex to half and speed to 10, still resulted in CDP duplex mismatch
error, or collisions. I remember reading something about a CDP bug, so
I just disabled CDP on that port.

ie (on 837)
ethernet 0
no cdp enable
exit

or (on switch)
fastethernet 0/24
no cdp enable
exit

 

under interface ethernet 0, I could not set it to half duplex. have to
disable cdp. it worked. thank you very much guys.

 

Hi, all,

Rather than disable CDP completely, you can issue the command:

no cdp log mismatch duplex

which just prevents the router reporting these errors.

 

I had the same issue. I fixed the speed on the 2950 end to 10Mbit/HD
and it went away. A bit of reading on the Cisco site at the time led me
to believe that the E0 port isn't full-duplex which is the bug. Rather,
it's a virtual interface of the 4 Fa ports which aren't proper
switchports unlike the 1800 series. Therefore, for simplicity, I treat
it as a hub.

 

At half duplex collisions are OK and normal - if you see frame or other
errors then you have a duplex mismatch.

none