Esa Maintenance Overview; Functional Description - Nortel DMS-100 Series Maintenance Manual

5 ESA maintenance overview

Functional description

The Star Hub is provided with the Emergency Stand-Alone (ESA) capability.
There is no ESA capability for the Star Module.
The Star Hub is a remote line concentrating device. The communication links
between the Star Hub and the host site can be damaged or cut. Service can be
interrupted. The ESA capability enables the Star Hub to provide stand-alone
call processing capability. The Star Hub must provide this call processing
ability if loss of communication with the host occurs. With the ESA capability,
the Star Hub emulates the call processing functions of the host line trunk
controller (LTC), line group controller (LGC), remote cluster controller 2
(RCC2), and central control (CC).
The Star Hub does not have a special card that supports the ESA capability.
Instead, ESA is a software capability that is in each of the NTTR77AA remote
controller packs (RCP). In the Star Hub, the ESA software running in the
RCPs communicate with the Star Hub software processes. This means that
ESA software is resident within both units of the Star Hub. Normally, the two
units of the Star Hub are active and working by load sharing. However, the
ESA software is only active in one unit and is inactive in the other unit.
When operating in the ESA mode, the Star Hub provides limited services to
subscribers. Only common line-to-line calls, for both dial pulse and dual tone
multifrequency (DTMF) lines, are supported. Subscriber and Automated
Message Accounting (AMA) call recording are not supported in ESA.
The Star Hub supports ESA warm entry and cold exit. Warm entry means the
Star Hub maintains established calls, except for ISDN calls, during entry into
ESA mode. Cold exit means the Star Hub releases all calls, including
established calls and calls being established.
A diagram of the ESA capability, from the view of the MAP (maintenance and
administration position) terminal, is in the following figure. This diagram
describes the Star Hub as a C-side node to the ESA capability. In the diagram,
the Star Hub is not in ESA mode.
DMS-100 Family NA100 Star Remote System XPM15 and up
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