Home Realm’s Purpose

A home realm is required because the home address for SIP NATs is used to create a unique encoding of SIP NAT cookies. You can define the home realm as a network internal to the Oracle® Enterprise Session Border Controller, which eliminates the need for an actual home network connected to the Oracle® Enterprise Session Border Controller. You can define this virtual home network if the supply of IP addresses is limited (because each SIP NAT requires a unique home address), or if all networks to which the Oracle® Enterprise Session Border Controller is connected must be private to hide addresses.

For example, you can define a public home realm using the loopback network (127.0.0.0) and using the home realm address prefix (for example, 127.0.0.0/8) for encoding addresses that do not match (all addresses outside 127.0.0.0/8) in SIP NAT cookies. The SIP NAT address prefix field can be used to accomplish this while keeping the ability to define an address prefix for the ream for ingress realm determination and admission control. By defining the SIP NAT address prefix as 0.0.0.0, the home realm address prefix is used to encode addresses that do not match.