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Cisco ONS 15454 DWDM Troubleshooting Guide, R7.0.1
78-17742-02
Chapter 1 General Troubleshooting
1.1.2 Terminal Loopbacks
When a port terminates a facility loopback signal, the signal only loops back to the originating port and
is not transmitted downstream. When a port bridges a loopback signal, the signal loops back to the
originating port and is also transmitted downstream.
Note In Table 1-1, no alarm indication signal (AIS) is injected if the signal is bridged. If the signal is
terminated, an applicable AIS is injected downstream.
The loopback itself is listed in the Conditions window. For example, the window would list the
LPBKFACILITY condition for a tested port. (The Alarms window would show the AS-MT condition
which means that alarms are suppressed on the facility during loopback.)
With a client-side SONET or ANSI facility loopback, the client port service state is OOS-MA,LPBK &
MT. However, any remaining client and trunk ports can be in any other service state. For SONET or
ANSI cards in a trunk-side facility loopback, the trunk port service state is OOS-MA,LPBK & MT and
the remaining client and trunk ports can be in any other service state.
With a client-side SDH or ESTI facility loopback, the client port is in the Locked-enabled,maintenance
& loopback service state. However, the remaining client and trunk ports can be in any other service state.
For MXP and TXP cards in a SDH or ETSI trunk-side facility loopback, the trunk port is in the
Locked-enabled,maintenance & loopback service state and the remaining client and trunk ports can be
in any other service state.
1.1.2 Terminal Loopbacks
The following sections give general information about terminal loopback operations and specific
information about ONS 15454 card loopback activity.
Table 1-1 DWDM Card Facility Loopback Behavior
Card/Port Facility Loopback Signal
TXP_MR_10E/TXP_MR_10E_C/TXP_MR_10E_L client
ports
Bridged
TXP_MR_10E/TXP_MR_10E_C/TXP_MR_10E_L trunk
ports
Terminated
TXP_MR_2.5G/TXPP_MR_2.5G client ports Terminated
TXP_MR_2.5G/TXPP_MR_2.5G trunk ports Terminated
MXP_2.5G_10E_C/MXP_2.5G_10E_L client ports Bridged
MXP_2.5G_10E_C/MXP_2.5G_10E_L trunk ports Terminated
MXP_MR_10DME client ports Bridged
MXP_MR_10DME trunk ports Terminated
MXP_MR_2.5G/MXPP_MR_2.5G client ports Bridged
MXP_MR_2.5G/MXPP_MR_2.5G trunk ports Terminated
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