CCM 5.1.3 REDUNDANCY

Answered Question
Sep 6th, 2008

Hello i have one CCM 5.1.3 and want add second CCM 5.1.3 but cisco says when i

introduce cluster i can have only one

publishe and all other is subscriber

subscriber have onle read database

and when publisher goes down i can't do any changes in the subscriber i think it's no so good

1) is this possible to have 2 publisher or soMETHING like this

2) can i have 2 TFTP server, one in the publisher second in the subscriber and is this work

Correct Answer by Rob Huffman about 8 years 5 months ago

Hi Mikheil,

You will need to go to CCM 6.x to have redundancy for many CCM Features as there is no way to have two actual Publishers. Here is the background (there is no way to do this on any CCM version until 6.x)

The configuration database is stored on a publisher server, and a read-only copy is replicated to the subscriber members of the cluster. Changes made on the publisher are communicated to the subscriber databases, ensuring that the configuration is consistent across the members of the cluster, as well as facilitating spatial redundancy of the database.

The publisher server is the only server that has read and write access to the configuration database. When configuration changes are made, other members of the cluster have a read-only copy of the database.

From this CCM SRND;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/4x/42clproc.html

This changes with the release of CCM 6.x;

In prior versions of Cisco Unified Communications Manager, subscriber servers in the cluster use the publisher database for READ/WRITE access, and only use the local database for READ access when the publisher database cannot be reached. With Cisco Unified Communications Manager Release 6.0, subscriber servers in the cluster READ the local database. DB WRITES happens in both the local database as well as the publisher database, depending on the type of data. DBMS (IDS) replication is used to synchronize the databases on the nodes of the cluster. When recovering from a failover conditions such as loss of WAN connectivity for extended period of time, the Cisco Unified Communications Manager databases need to be synchronized with any changes that may have been made during the outage. This process happens automatically when database connectivity gets restored. This process may take longer over low bandwidth and/or higher delay links.

Database modifications for CallProcessing

User Facing features can be made on subscribers. These include updates for:

Call Forward All (CFA)

Message Waiting Indication (MWI)

Privacy Enable/Disable

Do Not Disturb Enable/Disable (DND)

Extension Mobility Login (EM)

Monitor (for future use, currently no updates at the user level)

Hunt Group Logout

Device Mobility

CTI CAPF status for end users and application users

Credential hacking and authentication

From this 6.x SRND;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/callpros.pdf

Redundant TFTP Servers are supported and recommended :)

From this CCM SRND;

The TFTP service can be enabled on any server in the cluster. However, in a cluster with more than1250 users, other services might be impacted by configuration changes that can cause the TFTP service to regenerate configuration files. Therefore, Cisco recommends that you dedicate a specific server to the TFTP service in a cluster with more than 1250 users, with Extension Mobility, or with other features that cause configuration changes.

The TFTP server is used by phones and MGCP gateways to obtain configuration information. There is no restriction on the number of servers that can have TFTP service enabled, however Cisco recommends deploying 2 TFTP servers for a large cluster, thus providing redundancy for TFTP service.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/4x/42clproc.html#wp1051169

Hope this helps!

Rob

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Correct Answer
Rob Huffman Sat, 09/06/2008 - 07:07

Hi Mikheil,

You will need to go to CCM 6.x to have redundancy for many CCM Features as there is no way to have two actual Publishers. Here is the background (there is no way to do this on any CCM version until 6.x)

The configuration database is stored on a publisher server, and a read-only copy is replicated to the subscriber members of the cluster. Changes made on the publisher are communicated to the subscriber databases, ensuring that the configuration is consistent across the members of the cluster, as well as facilitating spatial redundancy of the database.

The publisher server is the only server that has read and write access to the configuration database. When configuration changes are made, other members of the cluster have a read-only copy of the database.

From this CCM SRND;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/4x/42clproc.html

This changes with the release of CCM 6.x;

In prior versions of Cisco Unified Communications Manager, subscriber servers in the cluster use the publisher database for READ/WRITE access, and only use the local database for READ access when the publisher database cannot be reached. With Cisco Unified Communications Manager Release 6.0, subscriber servers in the cluster READ the local database. DB WRITES happens in both the local database as well as the publisher database, depending on the type of data. DBMS (IDS) replication is used to synchronize the databases on the nodes of the cluster. When recovering from a failover conditions such as loss of WAN connectivity for extended period of time, the Cisco Unified Communications Manager databases need to be synchronized with any changes that may have been made during the outage. This process happens automatically when database connectivity gets restored. This process may take longer over low bandwidth and/or higher delay links.

Database modifications for CallProcessing

User Facing features can be made on subscribers. These include updates for:

Call Forward All (CFA)

Message Waiting Indication (MWI)

Privacy Enable/Disable

Do Not Disturb Enable/Disable (DND)

Extension Mobility Login (EM)

Monitor (for future use, currently no updates at the user level)

Hunt Group Logout

Device Mobility

CTI CAPF status for end users and application users

Credential hacking and authentication

From this 6.x SRND;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/callpros.pdf

Redundant TFTP Servers are supported and recommended :)

From this CCM SRND;

The TFTP service can be enabled on any server in the cluster. However, in a cluster with more than1250 users, other services might be impacted by configuration changes that can cause the TFTP service to regenerate configuration files. Therefore, Cisco recommends that you dedicate a specific server to the TFTP service in a cluster with more than 1250 users, with Extension Mobility, or with other features that cause configuration changes.

The TFTP server is used by phones and MGCP gateways to obtain configuration information. There is no restriction on the number of servers that can have TFTP service enabled, however Cisco recommends deploying 2 TFTP servers for a large cluster, thus providing redundancy for TFTP service.

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/4x/42clproc.html#wp1051169

Hope this helps!

Rob

m.govorov Sun, 09/07/2008 - 06:35

Hi rob.huffman

thank you for your response

so how i inderstend i can made a chages any time in ccm 6 subscriber and that changes will be replication to the publisher ?

Rob Huffman Sun, 09/07/2008 - 07:28

Hey Mikheil,

First off, you are most welcome my friend!

This capability only applies to the "User Facing" features listed above. For example, in all previous versions of CCM if the Publisher was down no CFWDALL changes could be made on the user phones. Now these phones can set or unset CFWDALL due this new Subscriber ability to do these type of Database Modifications. Same with EM and the others that were listed. It's not like having two Publisher servers but is a Huge improvement in the overall cluster redundancy :)

With Unified CM 6.x, database modifications for user-facing call processing features are made on the subscriber servers to which the IP phones are registered. The subscriber servers then replicate these database modifications to all the other servers in the cluster, thus providing redundancy for the user-facing features.

(See “Call processing user-facing feature replication” in Figure 8-2.)

From this 6.x SRND;

http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/callpros.pdf

Hope this helps and makes sense!

Rob

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