Cisco Proxy TFTP Server supports two deployment models.

Cisco Proxy TFTP Server Deployment Model 1

For the deployment model illustrated in the following figure, the Primary TFTP Server should have Unified CM version 8.6 (2) or later.

The two remote clusters, Cluster A and Cluster B, are configured to the Primary TFTP Server. However, you can configure any number of remote clusters to the Primary TFTP Server. Whenever an endpoint sends a request for configuration file, the Primary TFTP Server looks into the local cache and the configured remote clusters. So, an endpoint that is configured to the Primary TFTP Server Cluster, Cluster A, and Cluster B can retrieve the configuration file and register to the Cisco Unified Communications Manager.

Note	Cisco recommends that you use deployment model 1 for better system performance. However, if you do not wish to change your existing Centralized TFTP (8.6 (1) or earlier), you can use deployment model 2.

Cisco Proxy TFTP Server Deployment Model 2

In the deployment model illustrated in the following figure, the centralized Unified CM TFTP server acts as a Primary TFTP server.

The two remote clusters - Cluster A and Cluster B have been configured to the Primary TFTP Server. However, you can configure any number of remote clusters to the Primary TFTP Server. Two more remote clusters have been added to the Cluster A. Whenever an endpoint sends a request for configuration file, the Primary TFTP Server looks into the local cache and the configured remote clusters (Cluster A and Cluster B). Cluster A further looks into its configured remote clusters (Cluster C and Cluster D). Thus, all the endpoints configured to the Primary TFTP Server Cluster, Cluster A, Cluster B, Cluster C and Cluster D can get the configuration file and get registered to the Cisco Unified Communications Manager.

Use Cases and Best Practices

Consider the following scenarios that detail how Proxy TFTP can be used and the best practices for implementation.

1. The cluster can act as just a proxy TFTP cluster with no other purpose. In this case, the cluster has no relationship with the other clusters, and does not process calls. For this scenario, the Remote Cluster TFTP is manually defined and rollback to pre-8.0 is recommended.

   Note	Autoregistration will not work in this scenario.

2. The cluster is a remote cluster that is also acting as a Proxy TFTP server for remote clusters. The remote cluster is manually defined, and Autoregistration should not be enabled.

Cisco Proxy TFTP Server can be configured manually as well as dynamically. This section provides configuration procedures for TFTP.

For large scale deployments, the Centralized TFTP server has the following limitations:

• Sometimes, endpoints are unable to download the configuration file because the primary TFTP server takes more time to get the configuration file from the alternate TFTP servers. By the time the primary TFTP server gets the file, the endpoints get timed out. As a result, endpoints never get registered to their Unified CM.

• Only 10 alternate TFTP servers can be added.

These limitations are not applicable to Cisco Proxy TFTP Server.

Note

When a phone requests a common file from a central or proxy TFTP server and that file has a common name such as ringlist.xml.sgn or is a locale file, the TFTP server sends its own local copy of the file instead of the file from the home cluster of the phone. The phone rejects the file due to a signature verification failure because the file has the signature of the TFTP server's local cluster, which does not match the Initial Trust List (ITL) of the phone. To resolve this issue, you can either disable Security By Default (SBD) for the phone or perform the bulk certificate export procedure to make the Trust Verification System (TVS) return a success when the phone verifies a signature from a different cluster. See the procedure in the "Default Security Setup" section of the Cisco Unified Communications Manager Security Guide for performing a bulk certificate export when migrating IP phones between clusters to perform the bulk certificate export. To disable Security by Default, see the procedure to update the ITL file for IP Phones in the Cisco Unified Communications Manager Security Guide.

For phones configured to remote clusters, first-time phone registration may take a few minutes. The time delay is due to Proxy TFTP Server searching for the configuration file in the remote clusters. The delay will vary based on the number of end points and the number of remote clusters configured. However, subsequent registrations will not have any delay.

The following system requirements exist for Cisco Proxy TFTP Server:

• Cisco Unified Communications Manager, Release 8.6 (2) or higher

• Cisco TFTP service - should be activated and in running state

This section provides the details of interactions and restrictions for Cisco Proxy TFTP Server.

Endpoints in a Cisco Unified Communications Manager cluster are configured with Proxy TFTP (for example, through Dynamic Host Configuration Protocol, or DHCP). Proxy TFTP can find the target cluster of the endpoint.

Note	It is recommended that you keep the Proxy TFTP on the current release while you upgrade the rest of the clusters, as well as have a combination of nonsecure and mixed-mode clusters.

The Proxy TFTP server does not have to be on the highest Unified Communications Manager release, and clusters in a Proxy TFTP deployment can be either nonsecure or in mixed-mode.

Proxy TFTP can find the target cluster of endpoints because the MAC address of the endpoints is part of the filename in the TFTP GET request (for example, SEP001956A3A472.cnf.xml.sgn). Proxy TFTP discovers the target in the following way:

1. Proxy TFTP polls all the clusters that it controls for the requested file, starting from its own database.

2. The cluster where the endpoint is configured returns the file.

3. The locale and ring list file requests do not contain a MAC address, so Proxy TFTP returns its own copies of these files.

   Note	The locale and ring list files are backward compatible for Unified Communications Manager releases.

When Security-by-Default (SBD) was introduced for Unified Communications Manager, Proxy TFTP (and TFTP servers in general) served both signed and nonsigned requests.

If the home cluster of an endpoint does not accept the ITL file request, the endpoint requests a default ITL file which the Proxy TFTP serves. After the endpoint receives the configuration file from its home cluster, the endpoint cannot validate the signature, because the endpoint has the ITL file from the Proxy TFTP and not its home cluster.

After you install Cisco Unified Communications Manager, your network can support the Cisco Proxy TFTP Server feature if you perform the necessary configuration tasks. For information on configuration tasks that you must perform, see the TFTP Setup

In Cisco Unified Communications Manager Administration, use the Advanced Features > Cluster View menu path to configure remote clusters.

Tips About Finding Remote Clusters

The Find operation locates only those remote clusters that you added previously. The Find operation does not locate the clusters that belong to the enterprise automatically.

Using the GUI

For instructions on how to use the Cisco Unified Communications Manager Administration Graphical User Interface (GUI) to find, delete, configure, or copy records, see the “Navigating the Cisco Unified Communications Manager Administration Application” section in the Cisco Unified Communications Manager Administration Guide and its subsections, which explain how to use the GUI and detail the functions of the buttons and icons.

Configuration Settings Table

The following table provides detailed descriptions of the remote cluster settings that you configure in the Cluster View window (Advanced Features > Cluster View).

The following table provides detailed descriptions of the remote cluster settings that you configure in the Remote Cluster Manually Override Configuration window (Advanced Features > Cluster View > TFTP).