MERLIN LEGEND Communications System Release 5.0
Feature Reference
555-650-110
Issue 1
June 1997
Features
Page 87
Basic Rate Interface (BRI)
3.
The loop clock source on any 100D module in T1 mode emulating tie
trunks.
4.
The local clock source on any 100D module.
NOTE:
Ports that are not in service should never be programmed as clock
sources.
Clock Switching
3
When the primary clock source is not able to provide the system clock, the
secondary clock source is used, if it exists and is capable of providing the system
clock. If the secondary clock source is incapable of providing the system clock,
the tertiary clock source is used. If none of these is capable of providing the
system clock, the communications system selects a system clock.
The system searches 800 NI-BRI and 100D modules for a clock source, starting
from the first module in the system and ending with the last module. The clock is
chosen with the following order of preference.
1.
Loop clock source on an 800 NI-BRI or 100D module.
2.
Local clock source on an 800 NI-BRI or 100D module.
3.
Local clock source on the processor module.
Timers and Counters
3
This option sets the timer and counter thresholds. The factory settings for
thresholds are standard and rarely need to be changed (see “At a Glance” in this
section for factory settings and valid ranges). When no response is received from
the network before the duration of the timer setting, the communications system
takes the appropriate corrective action.
The programmable timers and counters are as follows:
■
T200 Timer. Times the minimum time that the link layer waits for an
acknowledgment of link establishment, information, or polling supervisory
frames sent from the communications system to the network before
resending the frames.
■
T203 Timer. Maximum time that the link layer can remain inactive.
■
T303 Timer. Times the delay in network response when the
communications system sends a setup message to initiate an outgoing
call.
■
T305 Timer. Times the delay in network response when the
communications system sends a disconnect message to clear a call.
■
T308 Timer. Times the delay in network response when the
communications system sends a release message to clear a call.
