Cisco ONS 15454 SDH - Troubleshooting Non-DWDM Circuit Paths with Loopbacks

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Cisco ONS 15454 SDH Troubleshooting Guide, R5.0
July 2005
Chapter 1 General Troubleshooting
1.1 Troubleshooting Non-DWDM Circuit Paths with Loopbacks
• 1.8 Restoring the Database and Default Settings, page 1-107—Provides procedures for restoring
software data and restoring the node to the default setup.
• 1.9 PC Connectivity Troubleshooting, page 1-113—Provides troubleshooting procedures for PC
and network connectivity to the ONS 15454 SDH.
• 1.10 CTC Operation Troubleshooting, page 1-119—Provides troubleshooting procedures for Cisco
Transport Controller (CTC) login or operation problems.
• 1.11 Circuits and Timing, page 1-132—Provides troubleshooting procedures for circuit creation
and error reporting as well as timing reference errors and alarms.
• 1.12 Fiber and Cabling, page 1-136—Provides troubleshooting procedures for fiber and cabling
connectivity errors.
• 1.13 Power Supply Problems, page 1-144—Provides troubleshooting procedures for power supply
problems.
1.1 Troubleshooting Non-DWDM Circuit Paths with Loopbacks
Use loopbacks and hairpin circuits to test newly created SDH circuits before running live traffic or to
logically locate the source of a network failure. All ONS 15454 SDH electrical cards, STM-N cards,
G-Series Ethernet cards, MXP, TXP cards, and FC_MR-4 cards allow loopbacks and hairpin test circuits.
Other cards that do not allow loopback include E-Series Ethernet, ML-Series Ethernet, and DWDM
cards such as Optical Booster (OPT-BST), Optical Preamplifier (OPT-PRE), Optical Service Channel
and Combiner/Splitter Module (OSC-CSM), Band Optical Add/Drop Multiplexing (AD-xB-xx.x), and
Channel Optical Add/Drop Multiplexing (AD-xC-xx.x) cards.
To create a loopback on a port, the port must be in the Locked,maintenance Admin State and the
Locked-Enabled, loopback & maintenance service state.
Caution Facility (line) or terminal loopbacks can be service-affecting. To protect traffic, apply a lockout or Force
switch to the target loopback port. Basic directions for these procedures exist in the “2.10.2 Protection
Switching, Lock Initiation, and Clearing” section on page 2-260. For more information about these
operations, refer to the Cisco ONS 15454 SDH Procedure Guide Chapter 15, “Maintain the Node.”
Caution On STM-N cards, a facility (line) loopback applies to the entire card and not an individual circuit.
Exercise caution when using loopbacks on an STM-N card carrying live traffic.
1.1.1 Facility Loopbacks
The following sections give general information about facility loopback operations and specific
information about ONS 15454 SDH card loopback activity.