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New Member

extension mobility redunduncy

SRND of CUCM 6.x is talking about how to configure extension mobility redunduncy. i have configured them exactally as it mentioned in the document using Microsoft DNS Server. but even then redunduncy does not work. when i shutdown the publisher server then extension mobility also goes down. when i press the services button it just gets stuck at "requesting" and then in the end gives me error saying "host not found".

i have got CUCM Version

following are the changes implemented for this EM redunduncy to work

1. configured microsoft DNS server with a domain name called

2. configured hostname bb-agc-ccm-emrr under the above mentioned domain pointing to both the CUCM IP addresses. so the FQDN is

3. testing the name resolution through my pc and it resolved to both the server by doing ping and NSLOOKUP

4. changed the services URL IP Address in the enterprise parameters to FQDN.

5. configured the EM URL IP Address to FQDN

6. configured DHCP so that DNS server ip address could be assigned to IP phones.

7. reloaded the IP phones so that changes could take effect.

8. confirmed from IP phones web page that changes have taken effect in serives URL and DNS server.

9. restarted CUCM publisher and subscriber

10. removed the publisher ethernet cable for testing

11. but EM did not work it gave me error as it mentioned above.

Please tell me where i have gone wrong with this configuration.

thanks and regards


New Member

Re: extension mobility redunduncy


Is Extension Mobility service running on your second server?

New Member

Re: extension mobility redunduncy

yes its running on both servers.

New Member

Re: extension mobility redunduncy

verify that the phone is doing a DNS request twice otherwise the DNS is useful. because it may send an erronous response.

( by a sniff for example)

In this case, think to Cisco SLB on 6500 switchs.

It's just a point of view !


New Member

Re: extension mobility redunduncy

i do not think i can afford 6500 but i will definately will try to check IP Phones for DNS communication.


New Member

Re: extension mobility redunduncy


i configured everything pointing to subscriber ip address including services url and EM url even then phones could not connect to services when publisher is unavalaible.

I think EM on subscriber is not working. i have already checked EM service is running on the subscriber.

any suggestions



New Member

Re: extension mobility redunduncy

Hi Manish,

Did you find solution for this issue, actually we are facing the same issue excatly with the same call manager version.

I think there is problem with call manager version itself.

Thank you for you cooperation.



New Member

Re: extension mobility redunduncy