Extension Mobility Cross Cluster (EMCC)

EMCC is the ability to login to extension mobility in different clusters when using the Cisco UC distributed multi-cluster call processing model

Cisco Unified Communications Manger (CUCM) 8.0 introduces a new feature that many distributed multi-cluster call processing deployments have been waiting for…. extension mobility across clusters. And what technology feature would be worth talking about unless it had an acronym??? The new feature is referred to as Extension Mobility Cross Cluster (EMCC). CUCM 8.0 has also added support for secure Extension Mobility logins. Extension Mobility is the ability to login to a phone that is not programmed with your phone number, class of service, and other nerd knobs that we call features. Imagine that your company is Cisco Systems and you have an office at One Penn Plaza in midtown Manhattan (New York City). Since real estate is very expensive in NYC and Cisco is a virtualized company, most engineers and account managers (sales) do not have any permanent office space in NYC. A Cisco employee can borrow cubicle space for the day and use extension mobility to login to the Cisco phone. Extension Mobility allows someone in a temporary working space to have their phone number(s) follow them to their temporary phone. The phone configuration is also updated with various other configuration parameters based on the configuration of the device profile(s) that are associated to the end user. Extension Mobility was originally a feature of IPCC Express (re-branded to Unified Contact Center Express or UCCX) which required the purchase, maintenance, and configuration of the Cisco Customer Response Server (CRS) platform. Cisco integrated Extension Mobility functionality into CUCM 3.1, but extension mobility requires a standalone or centralized call processing model if using a CUCM version before 8.0. CUCM 7.0 introduced a new option in the publishing of Phone Services that allows extension mobility to be published as a global subscription. The global subscription nerd knob (check box) on the phone services configuration page of CUCM automatically subscribes every phone and device profile to the extension mobility service. Have you ever subscribed a Cisco IP Phone to the extension mobility service, but forgotten to subscribe the user’s device profile to the service? Been there… done that! If the Extension Mobility service parameter doesn’t allow multiple logins (default), the user will not be able to logout of the phone or login to any other phones. Configuring extension mobility cross cluster (EMCC) is nothing you should take lightly. EMCC requires a lot of configuration parameters including the exporting and importing of each neighbor cluster’s X.509v3 digital certificates. EMCC is supported over SIP trunks only. Presence is another feature that’s only supported over SIP trunks. If you want to be able to perform scalable Call Admission Control (CAC) in a distributed multi-cluster call processing model, you will need to point an H.225 or Gatekeeper controlled trunk to an H.323 Gatekeeper for CAC… but if you want to support presence and EMCC between clusters and maintain CAC… Houston! We have a problem here! Here are two potential solutions to the problem… but they’re both not scalable: 1)Assign the SIP trunks to a location and perform CAC in CUCM 2)Use Resource Reservation Protocol (RSVP) to provide CAC between clusters Option #1 above will require a lot of configuration in large environments that have dozens of CUCM clusters…. Option #2 above will seriously tax the CPU of your router because RSVP signaling requires a lot of processing. Service providers will never run RSVP with you either, but they will do pass-through RSVP where they can provide per-hop behavior (PHB) quality of service (QoS) based on the differentiated services code point (DSCP) markings of the IP packets. Here’s a link to the information you will need to be able to configure Extension Mobility Cross Cluster (EMCC): http://www.ciscosystems.ch/en/US/docs/voice_ip_comm/cucm/admin/8_0_2/ccmfeat/fsemcc.pdf

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