Perform A Facility Loopback On A Source-Node Port; Create The Facility Loopback On The Source-Node Port - Cisco ONS 15310-CL Troubleshooting Manual

1.2.1 Perform a Facility Loopback on a Source-Node Port

The tests in this section can be used to test DS-1, DS-3, or EC-1 circuits on a path protection. Using a
series of facility loopbacks, hairpin circuits, and terminal loopbacks, the path of the circuit is traced and
the possible points of failure are tested and eliminated. A logical progression of network test procedures
applies to this scenario:
1.
2.
3.
4.
5.
Note The test sequence for your circuits differs according to the type of circuit and network topology.
Facility and terminal loopback tests require on-site personnel.
Note
These procedures are performed when power connections to the nodes or sites are within necessary
Note
specifications. If the network tests do not isolate the problems, troubleshoot outward for power failure.
1.2.1 Perform a Facility Loopback on a Source-Node Port
The facility loopback test is performed on the node source port in the network circuit. Completing a
successful facility loopback on this port isolates the cabling and port as possible failure points.
Performing a loopback on an in-service circuit is service-affecting.
Caution
Loopbacks operate only on ports in the Out-of-Service, Maintenance (OOS,MT) administrative state and
Note
Out-of-Service and Management, Maintenance (OOS-MA,MT) service state. Brief instructions are
given in each procedure for changing the port's state. For more information about port state, refer to the
Cisco ONS 15310-CL and Cisco ONS 15310-MA Procedure Guide.

Create the Facility Loopback on the Source-Node Port

Connect an electrical test set to the DS-1, DS-3, or EC-1 port you are testing. For the ONS 15310-CL,
Step 1
this port is located on the 15310-CL-CTX. For the ONS 15310-MA, this port is located on the
DS1-28/DS3-EC1-3 or DS1-84/DS3-EC1-3.
Use appropriate cabling to attach the transmit (Tx) and receive (Rx) terminals of the electrical test set to
the port.
Adjust the test set accordingly.
Step 2
Cisco ONS 15310-CL and Cisco ONS 15310-MA Troubleshooting Guide, R7.0
1-4
Facility loopback on the source-node port
Hairpin on the source-node port
Terminal loopback to the destination-node port
Hairpin on the destination-node port
Facility loopback to the destination-node port
Chapter 1 General Troubleshooting
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