Extension Mobility Redundancy Issue

[alfonso.cornejo]

Hi to all,

I have an scenario of a publisher and a subscriber in my telephony infrastructure and i have configured EM for some extensions, the issue that i have is that the url for the EM service is pointing to my publisher server so when i turn it off for a HA test the EM service is no longer available.

I've searched for HA scenarios, there are suggestions about configuring a "redundant" EM service but this time the url should be pointing to the subscriber server, i did that and also the two services were showed in the ip phones and i was able to login using both EM services but when i turned off the publisher server to test it all the services were gone from my phones.

Is there something else besides the phone service for EM that i need to configure???? i also checked a dns solution using a name instead of an ip address in the url for the EM service but it doesn't work because of the behavior of dns that it doesn't know when a server is down so it could be resolving wrong ip addresses.

Thanks in advance for your help.

[Chandan_Thakur]

I checked in Lab, with these servers

• Callmanager(Two nodes cluster) running on 12.5.1.15900-66
• CIPC running on 8.6.6.0

I am not using any Load-Balancer.

Here is the initial setup

• Cisco Callmanager and EM services are running on both the nodes.
• Configured Phone service on both the nodes with address http://<FQDN-of-CUCM>:8080/emapp/EMAppServlet?device=#DEVICENAME#&loginType=DN 
• Subscribed the phone and Device Profile to both the phone services on Pub and Sub
• Logged in from CIPC to EMs on Pub and Sub one by one and worked fine

Now to check Extension Mobility Redundancy, here is what I did

• Phone is registered to Pub, and logged into EM on Pub.
• On Publisher I disabled Cisco Callmanager and Extension Mobility services.
  • Phone failed over for registration to Sub, however EM is still logged into Pub. I also logged out from EM and tried logging back to EM_Pub, and it logged in successfully .

To test further I did following:

• I deleted EM Phone service that i had for Subscriber, so now I have only one EM phone service on Publisher.
• Callmanager and EM Services are active and running on Subscriber node, however EM Phone service has been deleted on Subscriber.
• Now on Publisher node I disabled Callmanager and EM services (So EM phone service is only Publisher, CM and EM services are running only on Subscriber), CIPC failed over to Subscriber for registration and EM remained logged in Publisher. I again logged out and logged back in to EM Publisher without any issue.

Here is what i see from SRND 12.x

https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab12/collab12/cmapps.html?bookSearch=true#92657

High Availability for Extension Mobility

According to the EM architecture illustrated in Figure 18-4, reads and writes to the Unified CM database are required. EM is a user-facing feature, and database writes pertaining to EM can be performed by subscriber nodes. Therefore, if the Unified CM publisher is unavailable, EM logins and logouts are still possible.

Chandan Thakur
TAC-Engineer