Emergency Stand-Alone Operation; Signaling - Nortel DMS 100 Series Maintenance Manual

Emergency stand-alone operation

Emergency stand-alone (ESA) operation provides for maintenance operations
and a minimum set of call processing activities on the RSC-M. To allow ESA
operation capability, the ESA field in table RCCINV for the RSC-M must be
set to Y.
The RSC-M communicates with the host over links 0 and 2. If both of these
message links fail, the RSC-M cannot communicate with the host. The system
enters ESA. If the system enters ESA, an RSC-M can enter ESA. The RSC-M
can enter ESA because a loss of messaging to the host or the CC occurred. The
CC can cause this condition if a warm restart occurs for the CC and the CC
does not respond to the message audit. The RSC-M normally enters ESA
because of the complete loss of links.
Note 1: The PCM-30 links are not returned to service unless a minimum of
one line is present on the links in table LNINV. This event occurs to avoid
the possibility of generating SWERRs during ESA.
Note 2: The DC5A and DC5ADD calls that terminate are not intraswitched
in ESA. The DC5A and DC5ADD calls require outpulsing signals from the
maintenance trunk module (MTM) in the DMS switch.
The ESA provides limited call processing to the RSC-M node when a loss of
communication occurs with the host. When the systems enters ESA, the
peripheral takes control of call processing from the CC. The ESA entry is
warm. The system drops net-switched calls that require CC interruption. The
system maintains intraswitched calls.
A warm ESA exit occurs when C-side communications are restored with the
RSC-M. The RSC-M then attempts to return control to the CC. Calls that
originate during the ESA exit are held until the CC resumes call processing
activities. If an ESA exit attempt fails, the user executes a full RTS on the
module. This action causes a loss of calls in progress.

Signaling

The following figure shows the signaling interface of a CAS AMC to RSC-M.
Channels 0 and 16 of each PCM30 link perform messaging and control of the
voice channels on the link. Maintenance messaging uses channel 0 of the
associated link. The ABCD bits control CAS signaling on channel 16 of each
link.
On CAS interfaces, a 64 Kb/s PCM30 virtual line channel is logically mapped
to a singular PBX or subscriber line. A line card in the AMC supports this line.
Virtual lines appear as a line of the appropriate type in table IBNLINES. These
lines appear when the lines are entered at the DMS switch and AMC.
DMS-100 Family Remote Switching Center Multi-Access Maintenance Manual XPM11 and up
Maintenance overview 2-25