CUCM NIC duplex mismatch

Unanswered Question
Apr 7th, 2009
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HI There,

We currently run a CUCM 7.0(2) cluster. I detected an error message on the syslog of the catalyst switch, where the two call managers are connected. The error says this,

"CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet5/17 (not half duplex), with syd-ccm-02 bond0 (half duplex)."

I have checked both the interface Gi5/17 and the nic settings in the call manager's etho and both are set to auto. mode. See below for the details,

Gi5/17 in catalyst switch (4507):

#show int gi5/17

GigabitEthernet5/17 is up, line protocol is up (connected)

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 1000Mb/s, link type is auto, media type is 10/100/1000-TX

eth0 NIC: (call manager - MCS7825-h3)

admin:show network eth0 detail

Ethernet 0

DHCP : disabled Status : up

IP Address : IP Mask :

Link Detected: yes Mode : Auto enabled, Full, 1000MB/s

Duplicate IP : no

Queue Length : 1000 MTU : 1500

MAC Address :

RX stats:

bytes : 2365731208 packets : 16624908 errors : 0

dropped : 0 overrun : 0 mcast : 204461

TX stats:

bytes : 4293453743 packets : 35268789 errors : 0

dropped : 0 carrier : 0 colsns : 0


Primary : Secondary : Not Configured

Options : timeout:5 attempts:2

Domain :

Gateway : on Ethernet bond0

Can anyone please help me to pin point the mismatch issue?



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Anonymous (not verified) Wed, 04/15/2009 - 13:28
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The "CDP-4-DUPLEX_MISMATCH: duplex mismatch " is logged when CDP discovered mismatching duplex configuration on neighboring interfaces.

1. Configure the interfaces so they are both running at the same duplex (full- or half-duplex).

2. Disable CDP

3. Upgrade the ios image to version 12.3 or later.

Alexander.Khlem... Wed, 06/03/2009 - 01:00
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Hi Esteban,

We have exactly the same problem with CUCM 7.0(2a) servers connected to 3560G PoE-48 switches. Did you manage to find the solution to the problem?



egua5261 Wed, 06/03/2009 - 23:47
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Hi Alex,

Just need to restart the servers in order to sync up with the switch again; it seemed the issue was related to an older version of the IOS in our layer3 switch. Although the duplex/speed were set to auto on both the servers NICs and switchports there was a still a message coming up under the logs of the switch saying there was a duplex mismatch. The other way to fix is by hardcoding these paramaters on both ends.



Alexander.Khlem... Thu, 06/04/2009 - 00:41
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Hi Esteban,

We really prefer to keep them set to auto - the only way how we can use the 1Gb speed. Thanks a lot for the recommendations.




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