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.

Reply to
wxu3000
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what switch are you plugging the router into and how is the port configured ?

Reply to
Merv

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

Reply to
Merv

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

Reply to
bhalicki

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

Reply to
wxu3000

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

no cdp log mismatch duplex

which just prevents the router reporting these errors.

Reply to
john.stewart5

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.

Reply to
the_Muttster

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

none

Reply to
none

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