Cisco CUCM Deployment Models

Types of CUCM Deployment Models

There are basically four types of deployment models in Cisco Unified Communications Manager architecture. They are as follows:

  • Single Site
  • Multisite with Centralised Call-Processing
  • Multisite with Distributed Call-Processing
  • Clustering Over the IP WAN

Single Site Deployment Model:

  • This type of Deployment Model consist of a single CUCM or CUCM cluster (Publisher and Subscribers) located at a single site with no telephony services provided over WAN.
  • Maximum of 30,000 SIP or SCCP Phones.
  • The site may have a simplified dial plans which ease in troubleshooting.
  • No transcoding resources are required because of the use of a single high-bandwidth codec.
  • In case of single site deployment the calls are routed either within the same site or routed over the PSTN.
  • This type of deployment is recommended for small to medium sized business and where there is no requirement of IP Telephony over WAN. Example, they don’t have remote branch sites in different location, they operate from the same location.

Multi-site Deployment with Centralized Call Processing Model

  • This type of Deployment Model consist of a single CUCM or CUCM cluster (Publisher and Subscribers) located at a single site with IP Telephony services provided over WAN.
  • The remotes sites typically will have voice gateway and are connected to the central sites. The IP Phones at the remote sites registers to the CUCM located in the central site.
  • The IP WAN also carries call-control signaling between the CUCM cluster at the central site and the IP phones at the remote sites.
  • The remote sites completely relies on the centralized CUCM cluster to manager their call processing.
  • Applications such as voicemail servers, contact center servers are typically installed in the centralized site to reduce the cost of administration and maintenance.
  • In case of remote sites, during a WAN failure (SRST), the voice calls are not routed over WAN but are routed via the PSTN links.
  • This type of deployment is recommended where the remote sites has less number of users.

Multi-site Deployment with Distributed Call Processing Model

  • The Multi-site with distributed call processing consist of multiple independent sites with it’s own call processing agent connected to an IP WAN that carries voice traffic between the distributed sites.
  • CUCM, applications, and DSP resources may be located at each site.
  • The IP WAN carries signaling traffic only for intersite calls; signaling traffic for calls within a site remains local to the site. This way, the amount of signaling traffic between sites is reduced compared to a Centralized Call Processing model.
  • This is recommended for business that consist of multiple sites in multiple regions.

Clustering over the IP WAN

This type of deployment consist of Call Manager across multiple sites that are connected by an IP WAN with QoS features enabled. Clustering over IP WAN can support two types of deployments i.e., Local Failover Deployment Model and Remote Failover Deployment Model.

  • Local Failover Deployment Model – Local failover requires that you place the Unified CM subscriber/backup servers at the same site, with no WAN between them. This type of deployment is ideal for two/four sites with Unified CM.
  • Remote Failover Deployment Model – Remote failover allows you to deploy primary and backup call processing servers split across the WAN. Using this type of deployment, you may have up to eight sites with Unified CM subscribers being backed up by UnifiedCM subscribers at another site.

Hope this helps!

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