System Networking; Centralized Control T-Net - Vertical Summit80 Manual

Vertical Summit80 & Summit800
Feature Description and Operation Manual
2.79

System Networking

2.79.1

Centralized Control T-NET

Description
In a Centralized Control T-NET (Transparent Network), a central system controls all remote
modules and terminals providing transparent networked access to all the features and functions
of the central system as well as the resources connected to the system.
Where the remote device is not directly reachable by the system, RTP packets must be relayed
through a local VoIP channel. A remote device may not be reachable when WAN access for the
device is through a firewall or NAPT server. In this case, the remote devices are assigned a zone
to manage RTP traffic between other devices connected in the T-NET. The zone defines when an
individual device requires use of the local VoIP channel. Zones are used to identify other group
characteristics as outlined in section Remote Device Zone Management.
Remote sites may include an system operating in the local mode as a live back up to the remote
central system. Under normal circumstances, the central system controls remote devices
(gateway Modules and terminals) including any local system VoIP channels. However, should the
WAN connection between the central system and the remote devices fail, the local system will
assume the call server responsibility for the local devices. The local system thus provides local
survivability and, based on configuration, may provide PSTN back-up service (Fail-over) for
internal calls that normally route over the WAN.
Under certain operating conditions, this equipment cannot be relied upon to make emergency
calls. Alternative arrangements should be made for access to the emergency services.
Operation
System
Operation of Centralized Network is automatic when configured & defined
Conditions
1. In a Centralized Network, the maximum number of channels available is the maximum
number of channels supported by the central system.
2. In T-NET, Centralized Miscellaneous functions (Relay support, MOH, BGM, Alarms
and External Page) are not supported but, all terminals in the T-NET can make and
receive pages.
3. When NAPT or other firewall functions are implemented, packet relay for RTP packets
is required. Packet relay requires VoIP channels for each simultaneous call desired.
4. The local system will take over operation of registered devices if the central controlling
system does not respond to three consecutive poll attempts over a 10-second period.
The central system will gain control automatically upon return of the WAN connection.
5. System can be installed behind a NAPT however, Fixed Nat – port forwarding is
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