NEC UNIVERGE SV9300 Networking Manual page 315

Outline of System Operation
• The CPU blade of Main Unit controls call processing, and Remote Unit follows the Main Unit in
normal operation mode.
• Remote Unit can accommodate analog Single Line telephones, Multiline Terminal, IP Station, and
LT/AP blades.
• Local Switch (TDSW) at Remote Unit connects an outside party when the Remote Unit is directly
connected to the PSTN/GSTN (Remote Unit-1 in the above figure).
• In the case of connections between Main Unit and Remote Unit, or Remote Unit and Remote Unit,
the voice path is connected via Peer-to-Peer or VoIPDB.
• If the communications between Main Unit and Remote Unit are interrupted, the Remote Unit starts
a survival mode operation after the system reset.
Outline of Survival Mode Operation
• Remote Unit system watches a Keep Alive signal sent from Main Unit regularly.
• If a line failure occurs (Keep Alive signal is not received), Remote Unit resets the own system and
starts survival mode operation as a stand-alone system to control the call processing within the Re-
mote Unit.
• During survival mode operation, Remote Unit system checks regularly whether the communications
with Main Unit is possible or not. When the Remote Unit regards that the communications are pos-
sible, the Remote Unit will change over to the normal mode to communicate with the Main Unit au-
tomatically or manually.
Chapter 3 REMOTE UNIT OVER IP FEATURES
3-3
SYSTEM OUTLINE
NWA-088654-001 Rev.1.0
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