When integrating a Cluster UCM with CUBE for PSTN calling, you can expect some calls that fails and some calls are successfull.
One of the most important aspect that you should consider when troubleshooting or designing your Dial Plan using Route List, Route Group and SIP Trunk to the CUBE are :
The IP Address Trust List on the CUBE in order to decide whether you should enable the Run on All Active Unified CM Nodes or not, if NOT, what UCM Group should we assign to the Route List and SIP Trunk.
Use Case 1 :
If all nodes are defined in the IP address trust list on CUBE.
Recommendation is to enable the "option Run on All Active Unified CM Nodes" on both Route List and SIP Trunk, provides you a greater amount of nodes to use for outgoing call routing and calls will egress other CUCM nodes. When this option is enabled, the UCM Group for both Route List and SIP Trunk is IRRELEVANT.
As you notice, the Server where the Endpoint is registered to is always used to initiate outbound call providing efficient distribution between nodes.
Activating “Run on All active Unified CM Nodes” on the SIP trunk and Route List. could cause some calls rejected, because the CUBE will accept calls only from the CUCM subscribers configured in the IP Address Trust list, in this scenario 10.1.5.17 and 10.1.5.18, the result the CUBE will reject calls from any other CUCM nodes such as 10.1.5.15 and 10.1.5.16, because as mentioned previously, when enabling this option on both Route List and SIP Trunk, the Server where the Endpoint is registered to is always used to initiate outbound call.
Recommendation is to disable the “Run on All active Unified CM Nodes” on both Route List and SIP Trunk.
But you should take care when disabling this option, in this case the node selection to initiate the outgoing call depends to the UCM Group associated to the Route List and SIP Trunk (through the Device Pool).
First you should consider that the calling device is Route List, NOT the Endpoint.
Second you should consider the nodes defined in the UCM Group for both Route List and Device. There are two possibility :
Use Case 2 :
If the Route List and the SIP Trunk are in the same UCM Group, consider the Route List is registered to a node which is also a member of the CUCM Group assigned to the SIP Trunk, the result is that the node on which the Route List is registered is always used to initiate the outbound call. In this case since the nodes 10.1.5.15 and 10.1.5.16 are not in the IP address Trust list of the CUBE. All calls will be rejected. Also using the same UCM Group on both Route List and SIP Trunk will cause all calls to egress on the node where the Route List is registered, and You do not get any load balancing with this.
Use Case 3 :
If the Route List is not registered to node which is a member of the CUCM group assigned to the SIP Trunk, then the node will randomly distribute the calls accross the nodes in the Trunk’s CUCM group. In this case recommendation is to ensure you define different UCM Group for Route List and SIP Trunk, in other words DO-NOT-COLOCATE the Route List and SIP Trunk in the same UCM Group and ensure that the servers or nodes in the UCM Group assigned to SIP Trunk are defined in the IP Address Trust list on the CUBE, thus the outgoing calls are load balanced across the nodes in the UCM Group’SIP Trunk.
To summarize :
If the CUBE is configured with all nodes in the IP Address Trust list. Recommendation and Best Practice is to enable the “Run on All active Unified CM Nodes” on both Route List and SIP Trunk.
If the CUBE is configured to accept calls only from some nodes. Recommendation and Best Practices is :
1-To disable the “Run on All active Unified CM Nodes” on both Route List and SIP Trunk.
2-Do-not-colocate the Route List and SIP Trunk in the same UCM Group.
3-Ensure that the nodes defined in the UCM Group’s SIP Trunk are the same as the nodes configured in the IP Address Trust list on the CUBE.
