How it Works

When configured for Survivability, the Oracle® Enterprise Session Border Controller operates in either normal or survival mode. In normal mode, the IP wide area network (WAN) connection between the remote Oracle® Enterprise Session Border Controller and the data center headquarters site is operational, and endpoints at the remote site register through the SBCs to an IP-PBX or Application Server (AS) at headquarters. Similarly, the Net-Net ESD forwards calls between endpoints to the IP-PBX or AS at headquarters. When an endpoint registers, the Oracle® Enterprise Session Border Controller inserts a registration entry for the endpoint in its local registration cache.

When the IP connection to headquarters goes down, the Oracle® Enterprise Session Border Controller operates in survival mode. In this mode, the system is able to detect any loss of connection (and subsequent re-connection) to the core data center based on a health score (For more information about health score, see Survivability Health Score ). When it detects a loss of connection, it enters survival mode and locally processes registrations and session traffic without routing them to the registrar. The Oracle® Enterprise Session Border Controller also handles call routing in this mode. When a subsequent re-connection is detected, the system exits survival mode and proxies all registrations and session traffic once again to the data center (normal mode).

In "Survival Mode", the ROBO Oracle® Enterprise Session Border Controller provides the following capabilities:

Maintains SIP registrations for local SIP phones (based on existing registration cache).
Provides local extension-to-extension calling and incoming public switched telephone network (PSTN), if available, to local extension dialing.
Provides extension-to-PSTN calling through a media gateway (assuming a gateway is available) or alternatively, via a configured SIP trunk/route.
Allows all new registration requests (without authentication) to be successful.
Allows extensions to be dialed based on its multiple user identities (either identified by using P-Asserted-Identity or BroadSoft’s proprietary mechanism). For more information about Survivability using a BroadSoft server, see Remote Site Survivability with a BroadSoft Server.

Survivability Health Score

When Survivability Mode is enabled on the Oracle® Enterprise Session Border Controller, the system is able to detect any loss of connection (and subsequent re-connection) to the Enterprise’s core data center based on a health score.

For the purpose of health monitoring, a sip-interface and one or more attached session agents can be logically grouped together by configuring a“service-tag” parameter to indicate the name of the session agent group. The service health score of the group is based upon the health status of the session agents within the group and can be configured using the session-agent-health parameter. The session-agent-health score can be a value between 0 and 100.

The determination of when to enter survival mode is determined by the session agent health score. The session-agent-health value is the amount that is deducted from the service health score when the session agent goes out of service. The sum of the service health values of all session agents assigned to a specific service tag must equal 100 to stay in normal mode. In cases where there is one session agent, the service health value is 100. For cases where there are two session agents, each session agent could have a service health of 50.

When the service health score goes down to zero the Oracle® Enterprise Session Border Controller enters survival mode. While in survival mode, the Oracle® Enterprise Session Border Controller continuously attempts to re-establish communications with the session agents. If communication is re-established, the Oracle® Enterprise Session Border Controller adds the service agent health value of the session agent to the current service health score, and survival mode is exited if the service health score is above zero.

Note:

For more information about configuring Survivability Mode and the Survivability health score, see Configuring Remote Site Survivability using the ACLI or Configuring Remote Site Survivability using the Web GUI.