Specifications

283
The “.CUS” Files
with no consideration to priority. If sufficient reserve memory is not available, the call is
terminated.
Paging delay parameters are: the queue limit (the maximum allowable number of pages
queued to each channel); and the bypass priority (the minimum priority a page must have
for it to bypass the paging delay limit and be accepted when the queue exceeds the
maximum length at a destination). Each channel has a queue limit and one system-wide
bypass priority level.
After the check for free memory space, if the call's priority is below the level that allows it
to bypass queue limits, the paging destinations are examined. The queue length at each
paging destination is compared to its limit; if the limit is exceeded the call is rejected.
The queue size and bypass priority parameters are programmed in options.cus. The
QueueLimit command sets the maximum number of pages that may be queued to any of
the channels listed in a subsequent Channel command. Setting it to zero (or OFF, NONE
or NO) disables the feature. The Channel command specifies a list of channels to which a
previous QueueLimit command is to be applied. The maximum queue limit for all
channels is OFF.
The BypassPrio command sets a priority level at which the queue limit is disabled. It
accepts arguments in the range 1-4, NEXT (Next Out) or BREAK (Breakthrough). Pages
at or above the specified priority bypass the queue length check. The default bypass
priority is four.
Load Management Reporting
All load management actions are reported in the system log file. Rejected calls are logged
with a leading character of “-”, indicating an error condition requiring the attention of the
system operator. The status logged is “no resrc” (no resource) if the memory usage limit
was exceeded, or “dest busy” (destination busy) if a channel queue length limit was
exceeded. Changes to the values of load management parameters are logged with a
leading character of “+”, indicating advisory information.
Critical Load Management
On extremely busy systems, internal load management (not settable by this command)
will become active when memory gets very low. Instead of playing a prompt, it will stop
scanning the trunk cards, and callers will hear extended ringback, until some pages go out
so the system recovers some memory. This applies to trunks, not TNPP. Also, priority B
and N pagers bypass this mechanism.