Special Loopback Configuration Conditions
This section describes all the special configuration settings that must be enabled
or disabled for certain loopbacks to operate properly. Other special loopback
rules are also provided in this section.
Remote CS Loopbacks
1.
T1 unloop codes will remove a CS Line loopback only if a DS Line loopback
currently exists.
2.
The Aux (drop-and-insert) port is unaffected by this function.
3. Terminal Timing Mode
(described in Chapter 6) must be
OFF
, if there is no
DTE connected to the local port.
4.
CSLOOP=CSLINE
and
CSLOOP= CSDTE
are valid only if the port has been mapped
to at least one DS0.
Near-End Loopbacks
1.
LS DTE and DS DTE Loopbacks require that the Access-T not be timed
from the network (i.e.,
MASTER
≠
LINE
). (During an LS DTE or DS DTE
loopback, the received data path is disconnected from the network.)
Likewise, when an LS DTE or DS Line loopback is established, the Access-T
cannot be the timing source (
MASTER=LINE .)
2.
When DS Line Loopback is initiated (locally or remotely), CS DTE Loopbacks
are also initiated at all mapped DTE ports.
3.
During LS DTE loopback, Access-T must be connected to a T1 line or
Access-T’s T1 line output must be terminated with 100 ohms. If there is no closed
connection or termination at the line interface during LS DTE loopback, spuri-
ous errors may be introduced in the looped circuit.
4.
Before a Line Loopback can be established, any existing Line Loopbacks must
first be removed.
5.
Access-T does not support DS Line loopbacks when all DS0s are mapped to
the Aux Port and no DTE equipment is attached to the Aux Port.
Far-End Loopbacks
1.
Far-end loopbacks are not available on a Fractional T1 line. However, remote
CS Loops (V.54) are available.
Chapter 7
ACST-0351-005
Alarms, Reports, and Tests
June 1996
7-28