Using the Local Route Table (LRT) for Routing

The LRT allows the Oracle® Enterprise Session Border Controller to determine next hops and map E.164 to SIP URIs locally for routing flexibility.

The LRT uses a local route cache that is populated by a local XML file on the Oracle® Enterprise Session Border Controller. Each local cache is populated from one defined XML file. For routing, the local route cache operates in a way similar to the ENUM model where a local policy next hop specifies the local route table that the Oracle® Enterprise Session Border Controller references. For example, you can configure one next hop to use one table, and another next hop to use a different table.

Similar to the ENUM model, the Oracle® Enterprise Session Border Controller typically performs a local route table lookup using the telephone number (TN) of the SIP Request-URI. This is the user portion of the URI, and the Oracle® Enterprise Session Border Controller ignores user parameters or non-digit characters. The local route table XML file defines the matching number and the resulting regular expression replacement value such as ENUM NAPTR entries do. The Oracle® Enterprise Session Border Controller uses the resulting regular expression to replace the Request-URI, and it uses the hostname or IP address portion to determine the next hop. If the hostname or IP address matches a configured session agent, the request is sent to that session agent. If the Oracle® Enterprise Session Border Controller does not find a matching session agent for the hostname/IP address, the Oracle® Enterprise Session Border Controller either performs a DNS query on the hostname to determine its IP address or sends the request directly to the IP address.

When the next hop is defined as a user-parameter lookup key, such as a routing number (RN) or carrier identification code (CIC), the defined key is used for the local route table lookup.

The Oracle® Enterprise Session Border Controller can attempt up to 10 next hops per LRT entry in the order in which they appear in the XML file. If the next hop is unsuccessful, the Oracle® Enterprise Session Border Controller tires the next hop on list. An unsuccessful hop may occur when an out-of-service session agent or the next hop responds with a failure response.

Note:

Entering XML comments on the same line as LRT XML data is not supported.

The Oracle® Enterprise Session Border Controller can perform local route table lookups for SIP requests and communicate the results to the SIP task. The new task processes the new local routing configuration objects.

When a SIP call is routed, the Oracle® Enterprise Session Border Controller uses local policy attributes to determine if a local route table lookup is required. If a lookup is needed, the Oracle® Enterprise Session Border Controller selects the local routing configuration to use. Successful local route table lookups result in URIs that can be used to continue routing and redirecting calls.