SIP Registration Via Proxy
The Oracle® Enterprise Session Border Controller supports a number of features that require it to cache registration information for UAs (endpoints) registering and receiving requests through it. For those features to operate correctly, the Oracle® Enterprise Session Border Controller must act as the outbound proxy through which these endpoints register.
In order to support deployments where a proxy sits between the Oracle® Enterprise Session Border Controller and the endpoints, the Oracle® Enterprise Session Border Controller must consider the bottom Via header it receives from endpoints when constructing and matching cache registration entries. And when you use SIP port mapping, the system must use the bottom Via header as a way to determine the endpoint uniquely so that it can have a unique mapping port when the SIP interface is configured with the reg-via-key=all option.
Using the reg-via-proxy option, you can enable your Oracle® Enterprise Session Border Controller to support endpoints that register using an intervening proxy. You can set this option either for a realm or for a SIP interface. If you use it for a SIP interface, add to the SIP interface pointing toward the proxy and endpoints—the access side.
Considerations for Reg-Via-Key and Port Mapping
When you set the reg-via-proxy option, the Oracle® Enterprise Session Border Controller includes the bottom Via header from received requests in the registration cache Via Key. The system also uses it for determining whether or not the request matches a registration cache entry. Each unique bottom Via received a unique mapping port when you turn SIP port mapping on and set the SIP interface with the reg-via-key=all option.
Request Routing
So that requests addressed to the corresponding registered contact are routed to the proxy, the Oracle® Enterprise Session Border Controller includes the intervening proxy (i.e., the top Via) in the routing information for the registration cache when you set reg-via-proxy. To carry out this routing scheme, the system adds a Path header (if none is present) to the REGISTER. But it removes the Path header prior to sending the REGISTER to the registrar.
Note that when the received REGISTER contains a Path header, the Oracle® Enterprise Session Border Controller uses it for routing requests toward the endpoint and includes it in the forwarded REGISTER request—as is the case when you do not enable SIP registration via proxy.