Designing Dial Plan with Failover using Cisco SME Session Management Edition as centralized call routing for conferencing
Three separate Clusters CUCM are deployed with Multisite Architecture in the US site, GE site and AU site.
A single Cluster Cisco Meeting Server is deployed and distributed accross the WAN. Each Site contains two Cisco Meetine Server nodes running the callbridge services.
The Cluster CUCM in each site is trunked to the local callbridges.
Each cluster CUCM IS trunked to the SME as leaf nodes.
Standard Local Route Group will be used to reduce the number of Route Pattern, Route List, CSS and Partitions. The SIP Trunk selection for outgoing calls is based on the Route Group at the device pool level.
In each site, the call control contains two Route Groups, the first Route Group contains the SIP Trunks to the local callbridges and the second Route Group contains the SIP Trunk to SME.
On US-CUCM :
On GE-CUCM :
On AU-CUCM :
On each CUCM cluster (US, GE, AU and SME), a single route pattern pointing to a Route List containing two Local Route Groups.
In this deployment, the design of Device Pool is very important to achieve the goal of Load Balancing and Failover.
Device Pools in this deployment have three goals.
The first goal. For each site, routing calls to the local callbridges, if the local resources are not available, call must be sent to the remote callbridges.
In this case, a device pool for each site’s phones must contains two Local Route Groups :
Local Route Group LRG-LOCAL populated with the Route Group (RG-US, RG-GE and RG-AU) that contains the corresponding local callbridges.
Local Route Group LRG-REMOTE populated with the Route Group RG-SME that contains the SIP Trunk to SME.
You must create a device pool for each site (DP-US, DP-GE and DP-AU) and assign it to the phone.
On US-CUCM :
On GE-CUCM :
On AU-CUCM :
The second goal is for processing incoming calls from each site to SME. The SME must be able to process inbound calls when a specific Call Control wants to failover to another site in case of unavailability of the local resources.
For example, for users on US Site, if the local callbridges US-CMS1 and US-CMS2 are not available, the SME must process the incoming calls from US-CUCM in order to connect the users at the US Site to the remote callbridges (either to GE callbridges or AU callbridges) so that they will be used as a backup.
The same logic is valid to incoming calls from GE-CUCM and AU-CUCM.
To achieve this second goal, three device pools should be created on SME, let’s say DP-US-SITE, DP-GE-SITE and DP-AU-SITE.
Each device pool should have the following settings for the Local Route Groups LRG-LOCAL and LRG-REMOTE :
- The Local Route Group LRG-LOCAL should be set to NONE.
- The Local Route Group LRG-REMOTE should be set to the Route Group that contains two SIP Trunks towards the two remotes sites.
For US Site, SME should be configured with :
1-Route Group RG-US-SITE that contains the SIP Trunks to GE-CUCM and AU-CUCM.
2-Device Pool DP-US-SITE with :
- LRG-LOCAL = NONE
- LRG-REMOTE = RG-US-SITE
For GE Site, SME should be configured with :
1-Route Group RG-GE-SITE that contains the SIP Trunks to US-CUCM and AU-CUCM.
2-Device Pool DP-GE-SITE with :
- LRG-LOCAL = NONE
- LRG-REMOTE = RG-GE-SITE
For AU Site, SME should be configured with :
1-Route Group RG-AU-SITE that contains the SIP Trunks to US-CUCM and GE-CUCM.
2-Device Pool DP-AU-SITE with :
- LRG-LOCAL = NONE
- LRG-REMOTE = RG-AU-SITE
To make the failover process fine, SME must be able to process incoming calls from US GE and AU sites so that US Calls will be sent to GE or AU callbridges (GE calls to US or AU callbridges, AU calls to US or GE callbridges), we need to associate the Device Pool to the appropriate SIP Trunk.
The implementation should be :
- SIP Trunk to US-CUCM must be in the device pool DP-US-SITE
- SIP Trunk to GE-CUCM must be in the device pool DP-GE-SITE
- SIP Trunk to AU-CUCM must be in the device pool DP-AU-SITE
The third goal is to process the incoming calls at the remote sites when SME sends out the inbound calls after failover.
On each call control (US-CUCM, GE-CUCM and AU-CUCM), we need a device pool for calls coming from SME.
- US-CUCM with device Pool DP-SME
- GE-CUCM with device Pool DP-SME
- AU-CUCM with device Pool DP-SME
Each remote site must select the local callbridge to connect the call. In order to achieve this goal. The Local Route Group settings on each device pool must be set as follow :
On US-CUCM :
1-Route Group RG-US that contains the SIP Trunks to local callbridges US-CMS1, US-CMS2.
2-Device Pool DP-SME with :
- LRG-LOCAL = RG-US
- LRG-REMOTE = NONE
On GE-CUCM :
1-Route Group RG-GE that contains the SIP Trunks to local callbridges GE-CMS1, GE-CMS2.
2-Device Pool DP-SME with :
- LRG-LOCAL = RG-GE
- LRG-REMOTE = NONE
On AU-CUCM :
1-Route Group RG-AU that contains the SIP Trunks to local callbridges AU-CMS1, AU-CMS2.
2-Device Pool DP-SME with :
- LRG-LOCAL = RG-AU
- LRG-REMOTE = NONE
Then assign the device pool to the SIP Trunk that receives the incoming calls from SME as follow :
On US-CUCM :
SIP Trunk to SME must be in the device pool DP-SME.
On GE-CUCM :
SIP Trunk to SME must be in the device pool DP-SME.
On AU-CUCM :
SIP Trunk to SME must be in the device pool DP-SME.
Chart Call Flow
- Incoming call from a US endpoint to 882222 is recieved by on US-CUCM
- US-CUCM matches this call against the Route Pattern 882XXX, resolves that to Route List RL-CMS and then to the Local Route Groups LRG-LOCAL and LRG-REMOTE.
- With Standard Local Route Group LRG-LOCAL, US-CUCM uses the device pool of the endpoint to find the route group RG-US.
- The Route Group RG-US contains two SIP Trunks to the local CallBridge US-CMS1 and US-CMS2.
- US-CUCM sends the call to US-CMS1 or US-CMS2
- If all US CMS are unavailable, US-CUCM will route the call to another element in the Route List RL-CMS.
- US-CUCM select the second Standard Local Route Group LRG-REMOTE.
- US-CUCM uses the device pool of the endpoint to find the local route group RG-SME.
- The Route Group RG-SME contains only the SIP Trunk to SME.
- SME uses the Route Pattern to match this call to the Route List and then to the Local Route Groups LRG-LOCAL and LRG-REMOTE.
- With Standard Local Route Group, SME lookup the device pool DP-US-SITE of the SIP Trunk pointed to US-CUCM that received the call.
- Since the Local Route Group LRG-LOCAL is set to NONE.
- SME uses the second Local Route Group LRG-REMOTE and finds the Route Group RG-US-SITE.
- SME selects one of the SIP Trunks contained in the Route Group RG-US-SITE which are Trunk-To-GE-CUCM and Trunk-To-AU-Site.
- For example SME selects the SIP Trunk to GE-CUCM and sends out the call to it.
- GE-CUCM uses the Route Pattern to match this call to the Route List RL-CMS then to the Local Route Groups LRG-LOCAL and LRG-REMOTE.
- GE-CUCM uses the device pool of the SIP Trunk to SME that received the call DP-US.
- In the device pool, the LRG-LOCAL is set to RG-GE and the LRG-REMOTE is set to NONE.
- Finally GE-CUCM selects one of the SIP Trunks contained in the Route Group RG-GE which are Trunk-To-GE-CMS1 and Trunk-To-GE-CMS2.
- For example GE-CUCM selects the SIP Trunk to GE-CMS1 and sends out the call to it.