To first understand this option, first you need to understand that this option affects the outgoing call, more precisely when an endpoint let's say the HQ-Phone-1 registered to HQ-PUB dials the number of a space, and the call SIP INVITE is sent to the call control where the phone is registered to (affecting the "From" field and the Host Part of the URI in the SIP INVITE Header). The question that arises is : once the call is received by the Call Control, who is the initiator of the outgoing call in the Cluster CUCM with multiple Nodes running the Call Manager Services ?
The answer it depends, below you can see in some scenarios, the calling device is the Route List, NOT the endpoint, let me explain it :
We need first to dissect the outbound call process without this feature.
When an outbound call is initiated from an endpoint and sent to CUCM cluster. One node will do digit analysis and finds a route pattern.
There are two scenarios before extending the call to the SIP Trunk.
1-The Route Pattern points directly to the SIP Trunk. In this case the calling device is the endpoint.
- If the endpoint is registered to the same node which is a member of the CUCM Group assigned to the SIP Trunk, then the node on which the endpoint is registered will be used to initiate the outbound call.
- If the endpoint is registered to a node which is not 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.
2-The Route Pattern points to the Route List. In this case the calling device is the Route List.
- 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.
- If the Route List is registered to a node which is also a member of the CUCM Group assigned to the SIP Trunk, then the node on which the Route List is registered is used to initiate the outbound call.
According to this logic, there are two caveats when we have 8 Cisco CUCM for call processing or 16 in mega cluster:
- The first caveat: The Route List is only active on one CUCM node, which is not recommended since all outbound calls will be initiated by the node where the Route List is registered.
- The second caveat: if the SIP Trunk’s CUCM group is used, we can have max 3 CUCM servers to process outbound calls.
With the “Run on all active unified CM Nodes” option on either the Route List or the SIP Trunk, we can have max 8 nodes or 16 in mega cluster to process the outbound calls.
To summarize, the following definitions should be taken into consideration:
- Run on All Active Unified CM Nodes disabled on both Route List and SIP Trunk. The calling device is the Route List.
- Run on All Active Unified CM Nodes enabled on Route List, disabled on SIP Trunk. The calling device is the Endpoint.
- Run on All Active Unified CM Nodes disabled on Route List, enabled on SIP Trunk. The calling device is Route List .
- Run on All Active Unified CM Nodes enabled on both Route List and SIP Trunk. The calling device is the Endpoint.
1-Run on All Active Nodes disabled on both Route List and SIP Trunk - In this case the Route List is the calling device.
In this case, using the Route List and Route Group concepts, the Route List is the calling device. The endpoint HQ-Phone-1 with DN 5001 and HQ-Phone 2 with DN 5002 are registered to HQ-PUB and HQ-SUB respectively.
Case 1 :
- The Route List is registered to HQ-PUB 10.1.5.15.
- The SIP Trunk is associated to UCM Group SUB that contains HQ-SUB 10.1.5.14.
Because the calling device (Route List) is registered to CUCM HQ-PUB that is NOT part of UCM Group’s SIP Trunk. The outbound call is sent using the From header: "500X" <sip:500X@10.1.5.14>, the Server 10.1.5.14 in the UCM Group of the SIP Trunk is always used to initiate outbound call.
Case 2 :
- The Route List is registered to HQ-PUB 10.1.5.15.
- The SIP Trunk is associated to UCM Group PUB that contains HQ-PUB 10.1.5.15.
Because the calling device (Route List) is registered to CUCM HQ-PUB that is part of UCM Group’s SIP Trunk. The outbound call is sent using the From header: "500X" <sip:500X@10.1.5.15>, the Server 10.1.5.15 where the Route List is registered to is always used to initiate outbound call.
Case 3 :
- The Route List is registered to HQ-SUB 10.1.5.14.
- The SIP Trunk is associated to UCM Group PUB that contains HQ-PUB 10.1.5.15.
Because the calling device (Route List) is registered to CUCM HQ-SUB that is NOT part of UCM Group’s SIP Trunk. The outbound call is sent using the From header: "500X" <sip:500X@10.1.5.15>, the Server 10.1.5.15 in the UCM Group of the SIP Trunk is always used to initiate outbound call.
Case 4 :
- The Route List is registered to HQ-SUB 10.1.5.14.
- The SIP Trunk is associated to UCM Group SUB that contains HQ-SUB 10.1.5.14.
Because the calling device (Route List) is registered to CUCM HQ-SUB that is part of UCM Group’s SIP Trunk. The outbound call is sent using the From header: "500X" <sip:500X@10.1.5.14>, the Server 10.1.5.14 where the Route List is registered to is always used to initiate outbound call.
2-Run on All Active Nodes enabled on Route List, disabled on SIP Trunk - In this case the Endpoint is the calling device.
Case 1 :
- The Endpoint is registered to HQ-PUB 10.1.5.15.
- The Route List with Run On All Active UCM Nodes enabled. Note : The UCM Group is irrelevant for the Route List.
- The SIP Trunk is associated to UCM Group PUB that contains HQ-PUB 10.1.5.15.
The phone HQ-Phone-1 is registered in the HQ-PUB which is part of the UCM Group's SIP Trunk. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.15>, the Server 10.1.5.15 where the Endpoint is registered to is used to initiate outbound call.
The phone HQ-Phone-2 is registered in the HQ-SUB and this server is not in the UCM Group's SIP Trunk. The outbound call is sent using the following From header: "5002" <sip:5002@10.1.5.15>, the Server 10.1.5.15 in the UCM Group of the SIP Trunk is used to initiate outbound call.
Case 2 :
- The Endpoint is registered to HQ-PUB 10.1.5.15.
- The Route List with Run On All Active UCM Nodes enabled. Note : The UCM Group is irrelevant for the Route List.
- The SIP Trunk is associated to UCM Group SUB that contains HQ-SUB 10.1.5.14.
The Phone HQ-Phone-1 is registered in the HQ-PUB and this server is not in the UCM Group's SIP Trunk. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.14>, the Server 10.1.5.14 in the UCM Group of the SIP Trunk is used to initiate outbound call.
The phone HQ-Phone-2 is registered in the HQ-SUB which is part of the UCM Group's SIP Trunk. The outbound call is sent using the following From header: "5002" <sip:5002@10.1.5.14>, the Server 10.1.5.14 where the Endpoint is registered to is used to initiate outbound call.
3-Run on All Active Nodes disabled on Route List, enabled on SIP Trunk - In this case the Route List is the calling device.
Case 1 :
- The Endpoint is registered to HQ-PUB 10.1.5.15.
- The SIP Trunk with Run On All Active UCM Nodes enabled. Note : The UCM Group is irrelevant for the SIP Trunk.
- The Route List is associated to UCM Group PUB that contains HQ-PUB 10.1.5.15.
For both HQ-Phone-1 and HQ-Phone-2 Calls. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.15>, the Server 10.1.5.15 where the Route List is registered to is used to initiate outbound call.
Case 2 :
- The Endpoint is registered to HQ-PUB 10.1.5.15.
- The SIP Trunk with Run On All Active UCM Nodes enabled. Note : The UCM Group is irrelevant for the SIP Trunk.
- The Route List is associated to UCM Group SUB that contains HQ-SUB 10.1.5.14. Note : the Route List is the calling device.
For both HQ-Phone-1 and HQ-Phone-2 Calls. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.14>, the Server 10.1.5.14 where the Route List is registered to is used to initiate outbound call.
As you can notice, The Route List is only active on one CUCM server, as a result all outbound calls will be initiated by the server where the Route List is registered to. This is not recommended.
4-Run on All Active Nodes enabled on both Route List and SIP Trunk - In this case the Endpoint is the calling device.
In this case the UCM Groups for Route List and SIP Trunk are irrelevant. The Endpoint is the calling device.
- If the Phone is registered to HQ-PUB 10.1.1.5.15. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.15>, the Server 10.1.5.15 where the Endpoint is registered to is used to initiate outbound call.
- If the Phone is registered to HQ-SUB 10.1.1.5.14. The outbound call is sent using the following From header: "5001" <sip:5001@10.1.5.14>, the Server 10.1.5.14 where the Endpoint is registered to is used to initiate outbound call.
As you can notice, The Route List is only active on one CUCM server, In this case, if the Run On All Active Unified CM Node is NOT checked on both Route List and SIP Trunk, all outgoing calls can be initiated by the same node where the route list is registered (in other words as mentioned previously when the Route List is registered to a node which is also a member of the CUCM Group assigned to the SIP Trunk). And this is not recommended.
Solution : enable the "option Run on All Active Node" on both Route List and SIP Trunk, it gives you a greater amount of nodes to use for outgoing call routing. When this option is enabled, the UCM Group for both Route List and SIP Trunk is IRRELEVANT.
