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Cannot Reach Call Manager from Core Switch

Hi Guys,

I recently had an IP address conflict on my network, a device was installed with the same IP address as my CUCM 6.0. The device was removed and the IP address changed but we have been having problems ever since. I can be able to reach the Call manager from my PC which is conected to an access switch,but i cannot reach the CUCM from the core switch. Since the core switch is the gateway for the IP phones they lose connectivity to the call manager.

The problem is temporarily solved when i clear the arp cache, but 30 min later, i lose connectionon the IP phones again, and a ping from the switch(4506)cannot reach the CUCM. I have tried connecting the CUCM to a different switch and even making a static arp entry on the switch to no avail.

My last resort was to change the IP address for the CUCM but that still has not solved the problem and if i clear the arp cache everything is okay

What could be causing this problem? And what other steps could i take to correct this.

Thank you



Re: Cannot Reach Call Manager from Core Switch


Some other router or switch is pushing that bad MAC / IP back into the core.


Re: Cannot Reach Call Manager from Core Switch

Try a show log on all the devices in your network to verify that you do not have a duplicated ip address.

Then check if the IP that you are assigning to your CCM is NOT a broadcast ip address and finally check on your switch network for a broadcast storm.

Perhaps you can verify your ARP table (show arp) while having the problem and compare the IP address and the MAC address, if you have a different MAC then indeed somebody else is duplicating the ip address in your network.


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