Figure - Cisco ONS 15454 Troubleshooting Manual

1.2.1 Perform a Facility Loopback on a Source Electrical Port (West to East)
Facility, hairpin, and terminal loopback tests require on-site personnel.
Note
1.2.1 Perform a Facility Loopback on a Source Electrical Port (West to East)
The facility loopback test is performed on the node's source electrical port in the network circuit; in this
example, the DS-N port in the source node. Completing a successful facility loopback on this port
isolates the cabling, the electrical card, and the EIA as possible failure points.
example of a facility loopback on a source DS-N port.

Figure 1-11

Test Set
Caution Performing a loopback on an in-service circuit is service-affecting. To protect traffic, apply a lockout or
Force switch to the target loopback port. For more information about these operations, refer to the
"Maintain the Node" chapter in the Cisco ONS 15454 Procedure Guide.
Note Facility loopbacks require on-site personnel.
ONS 15454 DS-3 terminal loopbacks do not transmit an AIS in the direction away from the loopback.
Note
Instead of AIS, a continuance of the signal transmitted into the loopback is provided. A DS3/EC1-48
card can be provisioned to transmit AIS for a terminal loopback if desired.
Depending on your card type, complete the
DS3N-12, DS3i-N-12, or EC1 Port" procedure on page 1-10
Source DS3E or DS3XM Port" procedure on page
Create the Facility Loopback on the Source DS-1, DS-3, DS3N-12, DS3i-N-12, or EC1 Port
Connect an electrical test set to the port you are testing.
Step 1
Use appropriate cabling to attach the Tx and Rx terminals of the electrical test set to the EIA connectors
or DSx panel for the port you are testing. The Tx and Rx terminals connect to the same port.
Adjust the test set accordingly. (For specific procedures to use the test set equipment, consult the
Step 2
manufacturer.)
In node view, double-click the card to open the card view.
Step 3
Cisco ONS 15454 Troubleshooting Guide, R8.5
1-10
Facility Loopback on a Circuit Source DS-N Port
Source
ONS Node
DS-N XC OC-N
Destination
ONS Node
OC-N
"Create the Facility Loopback on the Source DS-1, DS-3,
or the "Create the Facility Loopback on the
1-11, then test and clear the loopbacks as instructed.
Chapter 1 General Troubleshooting
Figure 1-11 shows an
XC DS-N
November 2009