HA Citrix License Server via NetScaler (No MS Clustering please)

Working with large and complex Citrix environments, I always thought on how you can best HA your Citrix license server.  Now in days with many XenApp/XenDesktop deployments running with Citrix Provisioning (PVS), you license server becomes very important to have redundancy.  But how? there are several options, Citrix recommends MS Clustering. I’m no fan of MS clustering at all, so naturally the thought of two standalone servers with a Netscaler loadbalancer should work. With license service running on Windows, you have to activate licenses twice, because the licenses are tied to the hostname. Now, Citrix has released License Server VPX running a Linux appliance, which allows you to use the same hostname on two appliances, but with different IPs!. No  need to have duplicate license files.

All you have to do is to create a load balanced vServer on your Netscaler, point to the license server ports on both appliances, and then add weight to one appliance to be in compliance with license count.

The other option is to create a VIP pointing to a single host, then create a back up VIP pointing to the secondary license server and bind the back up VIP to your primary.  This will ensure all traffic goes to a single license server, and fail over only if the primary license server fails or you need to perform some sort of maintenance.

Ex:

XenApp Farm points to VIP: 10.10.68.10

VIP on NetScaler: 10.10.68.10

License Server VPX 1 (hostname ctxlic): 10.10.68.11

License Server VPX 2 (hostname ctxlic): 10.10.68.12

Weight set to 1 on VPX 2

Weight set to 2 on VPX 1

Set TCP monitor for this load balancer to ensure it is monitoring TCP 27000 traffic. Then you use the load balancer VIP as the License server in XenApp/XenDesktop/AG, etc configurations and you are done!