CCNA Voice Summary – Part 8

 CUCM (Cisco Unified Communication Manager / Call Manager)

Fully featured Voice and Video.

Supports up to 30000 IP phones per cluster in reality around 20000. A cluster is a shared database. Multi-server redundancy. Multi-site support. Very expensive compared to the rest. It runs on a hardened red hat Enterprise Linux platform as an appliance with no direct shell can run as a IU rack mount or a UCS blade server running in VMware ESXi. It stores all the data in an IBM Informix Database.

 CUCM Features:

It is a call processing Engine

Configuration is done mainly via web UI

It can function as a music on hold and conferencing server.

Can provide directory services for users (integrated or LDAP sync e.g. Microsoft Active Directory) and Presence services.

It has its own integrated Disaster recovery Subsystem (DRS) for backup and restore.

Cisco Unified Serviceability and Cisco RTMT provide ability for management and troubleshooting of log files and alarms and real time information.

 CUCM Per Server Specs:

Cisco UCS Servers:

Cisco UCS C210 Rack Mount Server – 7500 endpoints / server

Cisco UCS B200 Blade server – 7500

Cisco UCS C210 Rack Mount Server – 1000

Min Requirements of any server:





MCS 7845-13 – 10000 ENDPOINTS

MCS 7845 – 7500

MCS 7835 – 2500

MCS 7825 – 1000

MCS 7816 – 500

MCS 7815 – 300

CUCM 8 is the first version supported in VMware. UCS hardware has to be used if you are using the VMware EXSi. VMware has to be EXSi 4.0 with SAN attached and it must use .ova template files in order to bring up the servers. Migration from hardware based to virtualized can be performed using disaster recovery DRF. You can use a mixed hardware cluster during migration. The License key for CUCM uses the VMware virtual MAC address.

For lab, there is a default 150 demo device license units included. with any CUCM startup desk. You can install up to 3 servers.

VMware Specifics

2virtual CPUs. 6GB RAM. Two 80 GB hard disks at SCSI id 0:0 and 0:1. The UCS version 7 VM is supported. Up to 7500 users per VM. No USB support. Backups must be via SFTP.

CUCM Server Roles:

CUCM Data base Publisher DB Server (Pub) can only be 1. Makes all the changes and sync to the sub servers. Only it can do some special services e.g. presence, Dir. Sync with the LDAP, MVA. Publisher can be used as a CPE call processing engine in a lab environment. Can have up to 8 subscriber DB servers running as CPE. Up to 3 CPEs per USM Group.

CUCM DB Subscriber server. Can have up to 2 subs running as tftp servers. Additional sub servers to be used as media servers e.g. MOH, Conference, Annunciator – plays a message when you do something, MTP. MTP and Conference can only speak g711 protocol. Avoid these even in a lab environment.

CUCM DB Roles:

IBM Informix DB is a structured query language DB (SQL). It is owned and managed by the Publisher server. There is a one way replication e.g. from pub to subs. Most config changes are made on the Pub DB server but there are some DB fields that can be changed on sub servers local to where the phone is registered and then replicated to the pub. During a Pub outage, the only features that can be changed are the UFF features. These are called User Facing Features e.g. Call Forward all, MWI, Privacy for shared lines enabled/ disabled, hunt group login and logout, device mobility, credential authentication and certificate authority proxy function status for end users and application users.

CUCM Cluster Communication:

ICCS – Inter cluster Communication Signaling. It uses TCP 8002-8004. IT replicates all run time data between all CPEs in a cluster. CPEs are the CUCMs that are running the call manager service.

CDR call detail records and CMR call management records. They are logged by the CPE where the phone or gateway is registered. This data is periodically pushed to publisher server. Cisco CAR CDR analysis and Reporting lacks in the amount of features. CAR and 3rd party billing apps servers always point to and collect from the pub. When using a 3rd party, we need to push the data to another server then query it to the pub.

CUCM Traffic flow:

Signaling between CUCM and phones or gateways – SIP/SCCP

Media does not flow through the CUCM Cluster. Endpoints e.g. Phones and gateways talk directly via RTP Media (voice / video).

Between the gateway and the PSTN – TDM Signaling/ media.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s