What is a PUB and SUB?

[josephsarkis01]

                   I wanted to know if anybody can help me understand what is a PUB and SUB design for a CUCM. I know they are servers but I dont understand how they would work. Is ther a document at Cisco that explains a PUB and a SUB?

Joe

[Ayodeji Okanlawon]

Publisher

The publisher is a required server in all clusters, and as shown in Figure 8-1, there can be only one publisher per cluster. This server is the first to be installed and provides the database services to all other subscribers in the cluster. The publisher server is the only server that has full read and write access to the configuration database.

On larger systems with more than 1250 users, Cisco recommends a dedicated publisher to prevent administrative operations from affecting the telephony services. A dedicated publisher does not provide call processing or TFTP services running on the server. Instead, other subscriber servers within the cluster provide these services.

The choice of hardware platform for the publisher should be based on the desired scale and performance of the cluster. Cisco recommends that the publisher have the same server performance capability as the call processing subscribers. Ideally the publisher should also be a high-availability server to minimize the impact of a hardware failure.

Subscriber

During installation of the Unified CM software, you can define two types of servers, publisher and subscriber. These terms are used to define the database relationship during installation. When the software is installed initially, only the database and network services are enabled. All subscriber nodes subscribe to the publisher to obtain a copy of the database information. However, in order to reduce initialization time for the Unified CM cluster, all subscriber servers in the cluster attempt to use their local copy of the database when initializing. This reduces the overall initialization time for a Unified CM cluster. All subscriber nodes rely on change notification from the publisher or other subscriber nodes in order to keep their local copy of the database updated.

As shown in Figure 8-1, multiple subscriber nodes can be members of the same cluster. Subscriber nodes include Unified CM call processing subscriber nodes, TFTP subscriber nodes, and media resource subscriber nodes that provide functions such as conferencing and music on hold (MoH).

You can read more from the SRND here..Its an excellent document

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/callpros.html#wp1148528

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"

[testeven · Accepted solution]

Hi Joseph,

A Publisher server is required in all CUCM clusters. It is in charge of controlling the CUCM Database with full read/write access to it. It replicates this info to the other nodes (Subscribers). There is always one PUB and you can have more than one SUB in the cluster.

Usually the SUBs are used for call processing purposes, but the PUB can act as a call processing node too.

Please refer to the SRND below for more information:

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/8x/callpros.html

Regards, 

Tere. 

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[Adrian Saavedra · Accepted solution]

You can read CUCM SRND and System Guide.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/9x/callpros.html

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/admin/8_6_1/ccmsys/a02clstr.html

Hope to help, please remember to rate helpful posts.

Regards,

- Adrian.

[josephsarkis01]

Thank you for the info.As I read through the Cisco link for PUB and SUB. The Subcriber handles the calls volumes and all of the phone features and the Publisher is more for Database where the subcriber talks to the PUB for datebase info.

1 more question. Where would the contact center be in? The Subcriber? If the Subcriber goes down would the publisher act in place of the subscriber? Soory for all of these qyuestions but it's good to know these things rather then assume.

Joe

[Ayodeji Okanlawon · Accepted solution]

Joseph,

The contact center is a different element and it is a seperate unified communications component.

Yes the publisher can act as a call processing server if it is configured to do so. The SRND explains it. If you want to understand it better please read the SRND

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"There is a wideness in God's mercy Like the wideness of the sea.There's a kindness in His justice Which is more than liberty"

[testeven · Accepted solution]

Hi,

The UCCX/UCCE is a complete different server.

If one SUB goes down the PUB or a different SUB will act as a call processing agent. This is something you configure and it's called Callmanager Group. The servers will be available in a hierarchy, for example SUB2, SUB3, PUB.

Regards, 

Tere. 

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