Overview
Realms are a logical distinction representing routes (or groups of routes) reachable by the Oracle® Enterprise Session Border Controller and what kinds of resources and special functions apply to those routes. Realms are used as a basis for determining ingress and egress associations to network interfaces, which can reside in different VPNs. The ingress realm is determined by the signaling interface on which traffic arrives. The egress realm is determined by the following:
- Routing policy—Where the egress realm is determined in the session agent configuration or external address of a SIP-NAT
- Realm-bridging—As applied in the SIP-NAT configuration and H.323 stack configurations
- Third-party routing/redirect (i.e., SIP redirect or H.323 LCF)
Realms also provide configuration support for denial of service (DoS)/access control list (ACL) functionality.
Realms can also be nested in order to form nested realm groups. Nested realms consist of separate realms that are arranged within a hierarchy to support network architectures that have separate backbone networks and VPNs for signaling and media. This chapter provides detailed information about nested realms after showing you how to configure realms on your Oracle® Enterprise Session Border Controller.
About Realms and Network Interfaces
All realms reference network interfaces on the Oracle® Enterprise Session Border Controller. This reference is made when you configure a list of network interfaces in the realm configuration.
You configure a network interface to specify logical network interfaces that correspond existing phy-interfaces on the Oracle® Enterprise Session Border Controller. Configuring multiple network interfaces on a single phy-interface creates a channelized phy-interface, a VLAN. VLANs, in turn, allow you to reuse address space, segment traffic, and maximize bandwidth.
In order to reach the realms you configure, you need to assign them network interfaces. The values you set for the name and port in the network interface you select then indicate where the realm can be reached.
About the SIP Home Realm
The realm configuration is also used to establish what is referred to as the SIP home realm. This is the realm where the Oracle® Enterprise Session Border Controller’s SIP proxy sits.
In peering configurations, the SIP home realm is the internal network of the SIP proxy. In backbone access configurations, the SIP home realm typically interfaces with the backbone connected network. In additions, the SIP home realm is usually exposed to the Internet in an HNT configuration.
Although you configure a SIP home realm in the realm configuration, it is specified as the home realm in the main SIP configuration by the home realm identifier parameter. Specifying the SIP home realm means that the Oracle® Enterprise Session Border Controller’s SIP proxy can be addressed directly by connected entities, but other connected network signaling receives layer 3 NAT treatment before reaching the internal SIP proxy.
About Realms and Other Oracle® Enterprise Session Border Controller Functions
Realms are referenced by other configurations in order to support this functionality across the protocols the Oracle® Enterprise Session Border Controller supports and to make routing decisions. Other configurations’ parameters that point to realms are:
- SIP configuration: home realm identifier, egress realm identifier
- SIP-NAT configuration: realm identifier
- H.323 stack configuration: realm identifier
- Session agent configuration: realm identifier
- Media manager: home realm identifier
- Steering ports: realm identifier
- Static flow: in realm identifier, out realm identifier
