Specifications

X723-300151 1-7 Issue 2
1.2.3.3 Dual LIU Configuration Options
When fitted in port 1 or 2, the Dual LIU is configured from the channel
configuration options.
The following are selectable for each PCM line:
Multipoint mode: when selected, timeslots are connected directly
between the 2 line interfaces on the dual LIU,
by-passing the cross-connection of the system
controller. This can be useful in minimising
delays in a network. Individually selected
timeslots from either line may be
dropped/inserted to the cross connect switch in
either duplex or multipoint.
Terminal mode: when selected provides two independent PCM
trunks to the cross connect switch.
A/B mode: when selected provides a route protection
scheme for the line signal.
Signalling mode: this selects Channel Associated Signalling
(CAS), or 31 timeslot mode transparent to
Common Channel Signalling (CCS).
Fault logging: unused lines may have their alarms inhibited to
avoid unnecessary fault logging. When
inhibited the fault responses to the line (remote
frame and multiframe alarm bits) will not be
affected.
TS0 routing: it is possible to route the spare bits in TS0
either to the management patchfield or to the
cross-connect switch to provide management
routing and Remote alarm bit routing.
PCM Bypass: this allows the Dual LIU to be taken out of
service by activating the bypass relays on the
I/O adaptor. This facility may be used where a
standby LIU is fitted but not in service.
CRC4: Provides error performance monitoring using
CRC4. It may be enabled or disabled.
Low error rate threshold: this allows thresholds of 1 in 10
-4
, 1 in 10
-5
, or 1
in 10
-6
to be used to raise an alarm. Note that