Install a Session Initiation Protocol proxy server

We 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 we 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.

Ensure that we 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.

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, we 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: We must first have created a cell, deployment manager, and node when you installed WebSphere Application Server.gotcha

Create a proxy server on the node that you just federated, or on another node in the cell containing the cluster that the proxy will sit in front of by clicking Servers > Server Types > WebSphere proxy servers > New.

Avoid trouble: We must select the SIP protocol.gotcha 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, the SIP proxy server will be functional. However, if the SIP proxy server is fronted by an IP sprayer, 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.

The virtual host for the SIP container ports must be defined, and the SIP container(s) must be restarted after adding the new virtual host.gotcha

Subtopics

• Trusting SIP messages from external domains
  The general approach for providing secure communications between two independent domains or communities (each maintaining distinct directories) relies on identity assertion, where a trust relationship is established between two distinct domains using a certificate exchange during the setup of the physical SSL connection between the two domains.

• Load balancing with the Session Initiation Protocol proxy server
  Load Balancer for IBM WAS can help maximize the potential of the Web site by providing a powerful, flexible, and scalable solution to peak-demand problems. Configuration of a load balancer is critical to prevent any single points of failure at Session Initiation Protocol (SIP) proxy. Configuration of a load balancer is required when more than one SIP proxy is deployed.

• SIP proxy settings
  The SIP proxy settings page contains general configuration items that affect outbound transport configuration, toleration of IP Sprayer devices, and access logging configuration.

• SIP external domains collection
  The external domain collection panel provides create, remove and update capabilities for the external domain routing configuration.

• SIP external domains
  The external domain detail panel configures the properties for external domain routing.

• SIP routing rules collection
  Routing rules enable an administrator to direct Session Initiation Protocol (SIP) traffic to a specific cluster when there is more than one cluster running SIP applications in a WAS Network Deployment cell.

• SIP routing rules set order
  It is possible that a SIP message can match more than one routing rule but the SIP proxy will stop evaluating at the first match. Routing rules are evaluated in the order that they appear in the configuration file. The set order routing rule panel enables the administrator to change this ordering.

• SIP routing rules detail
  The routing rule detail panel provides the ability to create and modify individual rules. Since the structure of conditions is complex, the user will need to utilize a different set of panels to change the conditions associated with a rule.

• SIP rule condition collection
  Each rule contains a list of conditions that are combined using a logical AND operator. This means that all of the conditions need to be true for the rule to apply. This panel enables the user to manage the set of conditions.

• SIP rule condition detail
  Routing rules direct SIP requests that match the condition to the selected cluster. The condition setting specifies which SIP messages match the rule. Rules only apply to the initial message of a SIP conversation and not all SIP traffic. Use this panel to create or modify a rule.

• SIP proxy inbound channel detail
  This panel displays the configuration details of the SIP proxy inbound channel.

Related concepts

High availability and workload management with Session Initiation Protocol proxy server

Related tasks

Tracing a SIP proxy server