Nortel Media Gateway 3200 User Manual page 88

Notify command - The Notify command is used by the MG 3200 to inform the Call
Agent of events occurring on one of the Terminations.
Audit commands - The AuditCapabilities and AuditValue commands are used to query
the MG 3200 about Termination configuration and state. This information helps in
managing and controlling the MG 3200.
A H.248-configured MG 3200 starts by sending a ServiceChange command to its primary
MGC. If no response is received from it, the gateway goes on to the next MGC in its list.
When an MGC accepts the MG 3200 registration, the session can start. Subsequently, the
MG 3200 responds to MGC commands. Event notifications are sent only if the MGC
requests them specifically.
7.2.2.2 KeepAlive Notifications From the Gateway
The Keep Alive notifications from the gateway to the MGC are implemented either using
the proprietary mechanism via a NOP ServiceChange command (controlled by ini file
parameters), or using the standard inactivity timer package (H.248.14).
For the proprietary mechanism via a NOP ServiceChange command there are two
parameters:
KeepAliveEnabled - activates or de-activate the Keep Alive function
KeepAliveInterval - defines the inactivity period in seconds
If the KeepAlive mechanism is enabled, the MG 3200 sends a NOP ServiceChange
command when it detects a defined period without commands from the MGC (the default
period is 12 sec.) If no response is received from the MGC, the retransmission mechanism
is initiated and eventually causes a new ServiceChange command to be sent to the next
available MGC.
For the standard inactivity timer package (H.248.14) Inactivity detection is fully supported.
The activation is by requesting the 'it/ito' event on the root termination. The 'mit' parameter
of this event defines the inactivity period in 10 millisecond units. Note that this function is
not set by configuration. The Call Manager must send a request for this event.
7.2.2.3 Setting H.248 Call Agent IP Address and Port
Users can provide the MG 3200 with up to 5 IP addresses of the H.248 Call Agents using
the parameters, ProvisionedCallAgents and ProvisionedCallAgentsPorts.
The first Call Agent in the list is the primary one. In the case of a loss of connection, the
MG 3200 tries to connect with the next on the list, and it continues trying until one of the
Call Agents accepts the registration request. If the current connection is with a secondary
MGC, the MG 3200 starts again from the primary MGC. The current Call Agent can
override this setting by sending a ServiceChange command with a new IP address (not
necessarily in the original list) and a HandOff method. If no CallAgent IP address exists,
H.248 does not become operational.
Instead of defining an IP address, users can use a domain name for the Call Agent using
the CallAgentDomainName parameter. When using it, define also the DNSPRIServerIP
and DNSSECServerIP parameters. When using a domain name, the MG 3200 resolves the
name on each disconnection, allowing the user to switch to another Call Agent.
User's Manual 88
MG 3200
Document # LTRT-72704