Extension Mobility - Hardware Load Balancers

[Carl Ratcliffe]

Hi Support Community

We have implemented Citrix Netscalers on our LAN and I am going to take advantage of them for some voice services, in particular Extension Mobility.

I cant find it documented so hopefully someone with experience can advise me :

1. What do you monitor for Extension Mobility, is there a specific service or do you just monitor the CUCM server as a whole ?
2. Also to get to the Extension Mobility service you need to go through the phone settings, does this then mean you have to add the phone URL parameters to the load balancer ?

Thanks, Carl Ratcliffe

Preston Lancashire England

[Manish Gogna]

Hi Carl,

I have seen the scenario involving SLB ( VIP address method ). In that case when configuring Load Balancing we need to ensure that the Extension mobility service URL contains the ip address of the VIP rather than the Publisher or subscriber servers. Subscribe the phones to this service.

Here is a basic ACE Config For Load Balancing

 


1) Create the pub and sub servers


rserver host PUB
ip address 10.106.102.135
inservice


rserver host SUB
ip address 10.106.102.136
inservice

2) Create icmp probe and create serverfarm

serverfarm host CUCM-Pub
probe ping
rserver PUB
inservice
serverfarm host CUCM-Sub
probe ping
rserver SUB
inservice

probe icmp ping
 

3) create VIP ( Virtual Ip )

class-map match-any EM-VIP
3 match virtual-address 10.127.192.254 any
 

4) create loadbalancing policy-map

policy-map type loadbalance first-match EM
class class-default
serverfarm CUCM-Pub backup CUCM-Sub


5) create VIP policy map and apply it to the interface

policy-map multi-match EM-Policy
class EM-VIP
loadbalance vip inservice
loadbalance policy EM
loadbalance vip icmp-reply
nat dynamic 1 vlan 13


interface vlan 13
nat-pool 1 10.127.192.252 10.127.192.252 netmask 255.255.255.255 pat

 
Verify:
To verify this ensure that the VIP ip is pingeable, if yes you can then power-off your publisher to sumulate an outage & test for Extension Mobility functionality.

Manish

[Carl Ratcliffe]

Hi Manish

Thanks for your response.

Do you just use a ping to probe the CUCM server ? I thought there would be something else to probe as I have seen extension mobility fail quite a few times when the server is still online and pingable so in this scenario extension mobility would still fail if the only probe is ping.

Also if going through the phone options on a Cisco 8961 / 8841 to access extension mobility did you have to also have to load balance the phone options on the phone or does Cisco do this automatically ?

Thanks, Carl Ratcliffe

Preston Lancashire England

[Manish Gogna]

Hi Carl,

It appears to be the case, assuming that both the servers would not be co-located at a site or would not go down at the same time. Yes, there is possibility with EM login failing even with EM and Tomcat services being up but i have not come across such a config involving SLB.

For 89XX or 88XX series phones i do not see any special mention for SLB configuration so it should be okay.

Anyone with successful SLB implementation involving 88XX/89XX phones can confirm the same.

Manish

[Carl Ratcliffe]

Thanks Manish

The CUCM EM servers are geographically separated so adding it on with ping only will be far better than what we have now.

I will test the 89XX and 88XX phones and let you know. The reason I ask about these is because the 79XX phones I believe you have to amend the service URL in Enterprise Parameters to also make this load balance otherwise you couldn't even get as far as accessing the EM service - http://x.x.x.x:8080/ccmcip/getservicesmenu.jsp , I believe the 88/89xx phones work in a different way though.

Thanks, Carl Ratcliffe

Preston Lancashire England