H.323 Session Agents

H.323 session agents can include the following:

• Gatekeepers
• Gateways
• MCUs

Overlapping H.323 Session Agent IP Address and Port

You can now configure H.323 session agents to use overlapping IP addresses.

H.323 session agents continue are identified by their hostname when used in referencing configuration parameters—such as local policy next hops and session agent group destinations. This is why the hostname must be unique. However, when the Oracle® Enterprise Session Border Controller selects a session agent to use, it chooses the appropriate realm and H.323 stack based on the hostname. This is the case even if there are other session agents with the same IP address and port. Likewise, incoming calls are matched to the session agent based on the incoming realm.

There are no specific parameters to configure in order to enable this feature. For it to work properly, however, each H.323 session agent must be configured with a unique hostname (still the primary index). Otherwise, session agents with non-unique hostnames will overwrite one another.

To create overlapping H.323 session agents, you give each of them a unique hostname, which only serves to identify each individually. The Oracle® Enterprise Session Border Controller subsequently uses this label as the next hop destination in relevant local policy route entries.

Managing Session Agent Traffic

The Oracle® Enterprise Session Border Controller monitors availability, session load, and session rate for each session agent in real time. The session agent’s state is determined by its performance relative to the constraints applied to it and its availability.

The following table lists the conditions that cause the Oracle® Enterprise Session Border Controller to suspend the routing of traffic to a session agent, along with the criteria for restoring the route.

Constraint Condition	SIP Criteria	H.323 Criteria	Action	Criteria for Resuming
Maximum sessions exceeded	Maximum concurrent SIP sessions exceeded.	Maximum concurrent H.323 sessions exceeded. If the session agent is a gatekeeper and gatekeeper routed mode is not used, this constraint is an aggregate of all the destination gateways. Only maximum outbound sessions are measured.	Session agent is declared in constraint violation state.	Concurrent sessions drop below the maximum sessions value.
Maximum outbound sessions exceeded	Maximum concurrent outbound SIP sessions exceeded.	Maximum concurrent outbound H.323 sessions exceeded. If the session agent is a gatekeeper and gatekeeper routed mode is not used, this constraint is an aggregate of all the destination gateways. Only maximum outbound sessions are measured.	Session agent is declared in constraint violation state.	Concurrent sessions drop below the maximum outbound sessions value.
Maximum burst rate exceeded	Maximum burst rate exceeded in current window.	Maximum burst rate exceeded in current window. If the session agent is a gatekeeper and gatekeeper routed mode is not used, this constraint is an aggregate of all the destination gateways. Only maximum outbound sessions are measured.	Session agent is declared in constraint violation state.	Burst rate in subsequent window drops below maximum burst rate.
Maximum sustained rate exceeded	Maximum sustained rate exceeded in current window.	Maximum burst rate exceeded in current window. If the session agent is a gatekeeper and gatekeeper routed mode is not used, this constraint is an aggregate of all the destination gateways. Only maximum outbound sessions are measured.	Session agent is declared in constraint violation state.	Sustained rate in subsequent window drops below the maximum sustained rate.
Session agent unavailable or unresponsive	SIP transaction expire timer expires for any out-of-dialogue request. For example, INVITE, REGISTER, or ping.	Response timer expires. The default is T301=4 seconds. Connect timer expires. The default is T303=32 seconds. If the session agent is a peer gatekeeper, the LRQ response time is used to determine availability. The RAS response timer is 4 seconds.	Session agent is declared in constraint violation state or out-of-service. The time to resume timer starts.	Time to resume timer expires and the Oracle® Enterprise Session Border Controller declares the session agent in-service. or Session agent responds to subsequent pings (SIP only).