Exalt Installation and Management Guide
ExtendAir (TDD) Series
58
203591-004
2010-09-20
T1/E1 Loopback
Loopback is provided for any enabled T1 or E1 port. As shown in and , the choices are:
•
No Loopback (default)
•
External (local)
•
External (remote)
•
Internal
All loopback configurations control the loop at the Line Interface integrated circuit, which is the
device wired directly to the front panel ports.
External loopback modes are used in conjunction with an external test source. The designation of
‘local’ or ‘remote’ refers to where the loopback is occurring relative to the location where the loopback
is implemented. That is, on the radio being accessed, if External (remote) is selected, this loops the
signal back at the remote radio interface back towards the local radio. Likewise, if External (local) is
selected, the signal loops back at the local interface towards the remote radio (Figure 30 and Figure
31).
Figure 30 External (remote) loopback
Figure 31 External (local) loopback
When a local T1/E1 port is configured for External (remote) loopback, it is the same as configuring the
remote radio for External (local) loopback.
Internal loopback uses an internal test source, and sends the test source signal across the link, looped at
the remote radio’s interface, returned to the local radio, and looped at the local radio’s interface back to
the source. The inputs at both ends are looped back at the line level. illustrates the internal loopback
function.
Figure 32 Internal loopback
Note:
Only one Internal loopback can be enabled at any time.
