SIP maddr Resolution

Release S-C6.2.0 provides enhanced resolution of addresses found in SIP contact headers, or in the maddr (multicast address) parameter of SIP 3xx REDIRECT messages. Previous releases resolved these addresses as either a host address or as a session agent name. With Release 6.2.0 these addresses can also be resolved as session agent group (SAG) names.

Support for SAG-based resolution is provide by a new sip-config parameter, sag-lookup-on-redirect. By default, SAG lookup is disabled, providing compatibility with prior releases.

The following sample SIP REDIRECT and ACLI configuration fragment illustrate enhanced processing.

Status-Line: SIP/2.0 302 Moved
Message Header
Via: SIP/2.0/UDP
192.168.200.224:5060;branch=z9hG4bKa0fs40009o90sc8oo780.1
From: <sip:1111@192.168.1.222:6000>;tag=1
To: sut <sip:2223@192.168.1.224:5060>;tag=11
Call-ID: 1-28515@192.168.1.222
CSeq: 1 INVITE
Contact: <sip:1111@192.168.1.223;maddr=test.acmepacket.com>
Privacy: user;id;critical;session
P-Preferred-Identity: sipp <sip:sipp@192.168.200.222:5060>
P-Asserted-Identity: abc.com
Subject: abc
Proxy-Require: privacy,prack,abc
Content-Length: 0

session-group
        group-name                     test.acmepacket.com
        description
        state                          enabled
        app-protocol                   SIP
        strategy                       Hunt
        dest
                                       192.168.200.222
                                       192.168.200.223
...
...

In this case, when the Oracle® Enterprise Session Border Controller receives the 302, it resolves the information from maddr to a SAG name. In the above example, it will resolve to the configured SAG – test.acmepacket.com. The destinations configured in SAG test.acmepacket.com will be used to route the call.

SAG-based address resolution is based on the following set of processing rules.

When the Contact URI does not have an maddr parameter, and the hostname is not an IP Address, the Oracle® Enterprise Session Border Controller will look for a SAG matching the hostname.
When the Contact URI has an maddr parameter that contains an IP address, the Oracle® Enterprise Session Border Controller will not look for a SAG; it will use the IP Address as the target/next-hop.
When the Contact URI has an maddr parameter that contains a non-IP-address value, the Oracle® Enterprise Session Border Controller will look for a SAG matching the maddr parameter value.

The above logic can be turned on by enabling sag-lookup-on-redirect in the sip-config object as shown below.