Cisco ONS 15454 Troubleshooting Manual page 4

1.1 Network Troubleshooting Tests
Figure 1-4
and goes through the cross-connect card to the DS-N card. The terminal loopback on the DS-N card turns
the signal around before it reaches the LIU and sends it back through the cross-connect card to the OC-N
card. This test verifies that the cross-connect card and terminal circuit paths are valid, but does not test
the LIU on the DS-N card.
Figure 1-4
DS-N
ONS 15454 port loopbacks either terminate or bridge the loopback signal. In the ONS 15454 system, all
optical, electrical, Ethernet, and TXP/MXP facility loopbacks are terminated as shown in
During terminal loopbacks, some ONS cards bridge the loopback signal while others terminate it.
If an optical, electrical, Ethernet, and TXP/MXP port terminates a terminal or facility loopback signal,
this means that the signal only loops back to the originating port and is not transmitted downstream. If
the port bridges a loopback signal, the signal loops back to the originating port and is also transmitted
downstream.
All ONS 15454 card bridging and terminating behaviors are listed in
in the left column of this table originates a terminal or facility loopback, the signal behaves as listed in
the middle and right columns.
In Table
Note
AIS is injected downstream for all cards except Ethernet cards.
Table 1-1
Card/Port
DS-1
DS-3
DS-N transmux
All OC-N cards
EC-1
G-Series Ethernet
TXP_MR_2.5G
TXP_MR_10G
MXP_2.5G_10G
1. G-Series Ethernet terminal loopback is terminated and Ethernet transmission is disabled. No AIS is
inserted for Ethernet, but a TPTFAIL alarm is raised on the far-end Ethernet port.
2. G-Series facility loopback is terminated and no AIS is sent downstream. However, the Cisco Link
Integrity signal continues to be sent downstream.
Cisco ONS 15454 Troubleshooting Guide, R4.6
1-4
shows a terminal loopback on a DS-N card. The test-set traffic comes in on the OC-N card
Terminal Loopback Process on a DS-N Card
XC OC-N
1-1, no AIS signal is injected if the signal is bridged. If the signal is terminated, an applicable
DS-N, OC-N, EC-N, and TXP/MXP Card Loopback Behavior
Terminal loopback signal
Terminated
Bridged
Bridged
Bridged
Bridged
1
Terminated
Bridged
Bridged
Bridged
Test Set
Facility loopback signal
Terminated
Terminated
Terminated
Terminated
Terminated
Terminated
Terminated
Terminated
Terminated
Chapter 1 General Troubleshooting
Table
Table 1-1. When a port on a card
2
3
4
November 2004
1-1.