Takeover Capability - Nortel DMS-100 Series Maintenance Manual

As the data store fills near its capacity, the Star Hub overload controls reduce
its rate of load acceptance or stops the call process until store is available.
Overload control in the Star Hub occurs for
• C-side communication
• line scanning
When C-side communication reduces or stops, the RCP cards decrease the rate
they scan for messages on the C-side. By slowing the incoming load, the
demand for data store decreases. The MAP display queries of Star Hub status
are slower as are C-side responses to Star Hub-supported terminals.
During overload, the RCP cards also stop scanning the BIC until enough data
store is available. When the RCP cards do not scan the BIC, incoming work
from the P-side stops. This occurs by queuing the incoming work in the output
buffers of the BIC. When the buffers are full, the buffers accept no more work.
The results are partial dials or ignored keys on business sets.
Display of overload state
When the Star Hub becomes overloaded, the status display changes to ISTb
while both units show InSv. When operating company personnel enter the
QUERYPM FLT command at the STAR level, the phrase LCM Overloaded
is included in the response.
Log reports PM128 and PM181 indicate the overload condition in the Star
Hub. When call processing continues, PM128 is output with the phrase LCM
out of Overload.

Takeover capability

In the takeover mode, the in-service unit takes control of the lines connected
to the out-of-service mate unit and its lines. Also, the in-service unit has
access to the DS-1 C-side ports formerly used by the out-of-service mate. The
RCP card accesses all 36 line subgroups of the in-service unit. Takeover
occurs when
• one RCP card fails
• one power converter is not installed
• one C-side message port fails
Calls in process at the time of takeover terminate and the subscriber must
redial the number. The RCP card maintains calls already connected and in
progress. The RCP card in the mate unit supports all DS-1 links and the line
subgroups (LSG) of both units.
Star Remote System automatic maintenance 4-7
DMS-100 Family NA100 Star Remote System XPM15 and up