Installing a Session Initiation Protocol proxy server

You can install a Session Initiation Protocol (SIP) proxy server to initiate communication and data sessions between users. It delivers a high performance SIP proxy capability that you can use at the edge of the network to route, load balance, and improve response times for SIP dialogs to backend SIP resources. The SIP proxy provides a mechanism for other components to extend the base function and support additional deployment scenarios.

Before you begin

Ensure that you have a SIP application installed. The SIP container will not listen on a port without a SIP application installed. For a proxy server to be useful, you should have a cluster of SIP application servers.

About this task

The SIP proxy design is based on the HTTP proxy architecture and can be considered a peer to the HTTP proxy. Both the SIP and the HTTP proxy are designed to run within the same proxy server and both rely on a similar filter-based architecture for message processing and routing.

A SIP proxy serves as the initial point of entry, after the firewall, for SIP messages that flow into and out of the enterprise. The SIP proxy acts as a surrogate for SIP application servers within the enterprise. In fact, the nodes that host the SIP proxy servers host the public SIP domain of the enterprise. As a surrogate, you can configure the SIP proxy with rules to route to and load balance the clusters of SIP containers. The SIP proxy is capable of securing the transport, using secure sockets layer (SSL), and the content, using various authentication and authorization schemes.

The SIP proxy is also responsible for establishing outbound connections to remote domains on behalf of the back-end SIP containers and clients that reside within the domain that is hosted by the proxy. Another important feature of the SIP proxy is its capability to protect the identity of the back-end SIP containers from the SIP clients.

Avoid trouble: You must first have created a cell, deployment manager, and node when you installed WebSphere® Application Server.

Procedure

Create a proxy server on the node that you just federated, or on another node in the cell that contains the cluster that the proxy will sit in front of by clicking Servers > Server Types > WebSphere proxy servers > New.
Avoid trouble: You must select the SIP protocol.
You do not have to install the proxy server on a machine that also includes one of the servers in the cluster.

Results

After you choose a default cluster, your SIP proxy server will be functional. However, if the SIP proxy server is fronted by an IP sprayer, you must set up the loopback address and modify the inbound channel chains to make the SIP proxy server functional. See the load balancer documentation for information about setting up the loopback address.
Avoid trouble: The virtual host for your SIP container ports must be defined, and the SIP container(s) must be restarted after adding the new virtual host.