Specifications

Chapter 6 Troubleshooting and Diagnostics Installation and Operation Manual
6-24 Testing the Unit FCD-E1LC Ver. 1.0
This test checks end-to-end the data link, including the cables connecting the
remote user’s equipment to the FCD-E1LC, the remote FCD-E1LC, the
transmission plant connecting the two FCD-E1LC, and the local FCD-E1LC (except
for the data channel interface).
User's
Equipment
Local FCD-E1LC
Data
Channel
Main
Link
Remote FCD-E1LC
Sub Link
Main
Link
Data
Channel
User's
Equipment
Sub
Link
User's
Equipment
User's
Equipment
Transmission
Plant
Processor Processor
Figure 6-11. Data Channel Remote Loopback
Allowed Loopback Combinations
Not all of the loopback combinations are allowed, because some loopbacks
disconnect the signal paths of other loopbacks. If you try to activate an illegal
loop combination, FCD-E1LC sends a configuration error (ERROR 051: ILLEGAL
PORT LOOP COMBINATION).
For example:
• It is not possible to activate simultaneously remote (including
inband-activated) and local analog loopbacks on the main link because that
would disconnect the signal source for the local loopback.
• It is not possible to activate any remote data channel or sublink loopback
when any main link loopback (analog or digital, local, remote or
inband-activated) is activated
• It is not possible to simultaneously activate local and remote loopbacks on
the same data channel.
The following types of loopbacks can however be simultaneously activated:
• Main link: remote analog loopback and local digital loopback, and
inband-loopback activation together with BER testing
• Sublink: remote digital loopback and local analog loopback
• You can simultaneously activate loopbacks of any type on different data
channels, or a data channel and the sublink.
To help you decide when you are not sure whether you can activate an additional
loopback while one is already activated, you can find in the following tables
(
Table 6-5 to Table 6-12) systematic lists of allowed (Yes) and not allowed (No)
loopbacks for each combination of ports. Active indicates the already activated
loopback.
It is not possible to activate loopbacks on the Ethernet port. You can only
activate inband loopbacks and test the BER in the main link timeslots assigned to
the Ethernet port, to check transmission quality for the Ethernet payload.
Note