Network Deployment (Distributed operating systems), v8.0 > Applications > SIP applications > SIP in WAS > SIP high availability
SIP IP sprayer
SIP in WebSphere provides an IP sprayer.
Scaling a deployment to include multiple SIP proxies requires a front end load balancer. The WAS Edge Components Load Balancer provides this capability. It provides a feature called the SIP advisor that detects outages so that messages only flow to healthy SIP proxies. The health detection is done by sending a SIP OPTIONS message over TCP to the SIP proxies and looking for a response. The SIP proxy is configured with the host information from the load balancer, so it can detect that an OPTIONS message was sent for health checking. If an error response occurs, or if there is no response, or if the TCP connection fails, the SIP proxy is removed from the load balancer's active list. The SIP advisor continues to look for the SIP proxy after a failure.
The IP sprayer
- MAC forwarding is used to load balance the SIP proxies.
- The SIP advisor must be started.
- The interval between health check requests is configurable (default = 7 seconds).
Configure the SIP proxy
- The configuration for the IP sprayer will set the load balancer's host name and port, which will be used in outgoing SIP messages. This information will be gathered directly from the configured channel chains, and you do not need to configure any additional settings.
- The loopback device on the SIP proxy should be configured with the address the load balancer is listening on (cluster address, virtual IP address).
- The SIP proxy transport chains must be configured to listen on the loopback address.
SIP proxies publish client facing host interface information to the containers they are fronting via WLM. When fronted by an IP sprayer, the proxy will publish the IP sprayer information instead of its own host information. This information is inserted into Record-Route headers by the container for proxy applications running on the container. The SIP proxy also inserts this information into its via headers for outbound requests.
SIP high availability
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