Cisco ONS 15454 Troubleshooting Manual page 91

Chapter 1 General Troubleshooting
1.3.2 DS-3E and DS3i-N-12 Inhibit Loopback
DS-3E and DS-3i-N-12 cards respond to (but do not send) DS-3-level FEAC codes. You can inhibit
FEAC response on ports for these cards using the Inhibit Lbk check box on their Maintenance windows.
1.3.3 DS3XM-6 and DS3XM-12 Inhibit FEAC Loopback
DS3XM-6 and DS3XM-12 ports and transmuxed DS-1 circuits initiate loopbacks when they receive
FEAC line loop codes. If the Inhibit FE Lbk check box is checked for a DS-3 port, that port ignores any
FEAC line loop codes it receives and will not loop back (return them). Only DS-3 ports can be
configured to inhibit FEAC loopback responses; individual DS-1 ports (accessed on the DS3XM DS1
tab) cannot inhibit their responses. If you inhibit a DS-3 port's far end loopback response, this DS-3 port
and the DS-1 lines it contains are not restricted from terminal or facility loopbacks.
1.3.4 FEAC Alarms
When an ONS 15454 port receives an activation code for a FEAC loopback, it raises the
"LPBKDS3FEAC" condition on page
to deactivate the FEAC loopback. If a node sends a FEAC loopback command to the far end, the sending
node raises a
1.4 Troubleshooting Optical Circuit Paths With Loopbacks
Facility loopbacks, terminal loopbacks, and cross-connect loopback circuits are often used together to
test the circuit path through the network or to logically isolate a fault. Performing a loopback test at each
point along the circuit path systematically isolates possible points of failure.
The procedures in this section apply to OC-N cards. For instructions on G-Series Ethernet cards, see the
"1.5 Troubleshooting Ethernet Circuit Paths With Loopbacks" section on page
this section tests an OC-N circuit on a three-node BLSR. Using a series of facility, cross-connect, and
terminal loopbacks, the example scenario traces the circuit path, tests the possible failure points, and
eliminates them. The logical progression contains seven network test procedures:
The test sequence for your circuits will differ according to the type of circuit and network topology.
Note
1.
2.
3.
4.
5.
6.
7.
Facility and terminal loopback tests require on-site personnel.
Note
November 2009
"LPBKDS3FEAC-CMD" condition on page 2-168
A facility loopback on the source-node OC-N port
A terminal loopback on the source-node OC-N port
A cross-connect loopback on the source OC-N port
A facility loopback on the intermediate-node OC-N port
A terminal loopback on the intermediate-node OC-N port
A facility loopback on the destination-node OC-N port
A terminal loopback on the destination-node OC-N port
2-168. The condition clears when the port receives the command
Cisco ONS 15454 Troubleshooting Guide, R8.5
1.3.2 DS-3E and DS3i-N-12 Inhibit Loopback
for the near-end port.
1-68. The example in
1-47