Configuration Guide for Cisco NCS 1001, IOS XR Release 25.x.x

Configure OTDR in expert mode

Updated: July 27, 2026

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Use this procedure to configure expert mode OTDR scan parameters when automatic adjustment is not used for the selected port and direction.

Configure expert mode when you must control capture length, offset, resolution, sensitivity, measurement time, pulse width, span length, and relative thresholds.

Expert mode does not run a training phase and does not automatically adjust scan parameters.

Procedure

	1.	Enter configuration mode. Example: `configure`
	2.	Use the hw-module command to enter OTDR expert mode configuration for the slot, port, and direction. hw-module location 0/RP0/CPU0 slot slot-number otdr port port-number direction direction mode-expert Example: `hw-module location 0/RP0/CPU0 slot 2 otdr port 1 direction tx mode-expert`
	3.	Configure the expert mode scan parameters. For parameter descriptions, ranges, and defaults, see OTDR expert-mode parameters. Example: `pulse-width 10 span-length 1 measure-time 180 capture-length 1 capture-offset 0 fiber-resolution 4 loss-sensitivity 4 reflection-sensitivity -300 loss-relative-threshold 20 reflection-relative-threshold 20`
	4.	Commit the configuration and exit configuration mode. Example: `commit end`

OTDR expert mode is configured for the selected port and direction.

OTDR expert mode parameters

Use these values when configuring OTDR expert mode.

Table 1. OTDR expert mode parameters
Parameter	Description	Range	Default
capture-length (km)	Distance of the measurement endpoint.	1 to 150	100
capture-offset (km)	Start point of the measurement.	0 to 150	0
fiber-resolution (m)	Distance between measurement steps.	0 to 100	25
loss-sensitivity (in 0.1 dB)	Limit under which the loss is not considered a real loss.	4 to 50	6
measure-time (sec)	Time required to perform the complete optical scan.	1 to 360	180
pulse-width (ns)	Pulse duration during the measurement.	8 to 100,000	1000
reflection-sensitivity (in 0.1 dB)	Limit under which the reflection is not considered a real reflection.	-400 to -140	-300
span-length (km)	Length of span.	1 to 150	100
loss-relative-threshold (in 0.1 dB)	Threshold to compare the OTDR loss value plus the relative loss threshold with the baseline value.	1 to 300	2
reflection-relative-threshold (in 0.1 dB)	Threshold to compare the OTDR reflection value plus the relative reflection threshold with the baseline value.	1 to 300	2

Note

From Release 7.5.1, the plus sign labels in positive range values are removed in the Cisco NCS 1001 CLI help description.

Start OTDR measurement in expert mode

Start expert measurement after OTDR parameters are configured in expert mode.

The scan continues in the background after the command starts the action.

Procedure

Start the OTDR expert mode scan.

hw-module slot slot-number otdr port port-number direction direction scan expert

Example:

hw-module slot 3 otdr port 1 direction tx scan expert

The system displays the message "Otdr action will continue in the background."

What to do next

To see the measurement status, use the show hw-module slot slot-number otdr status command.

Display the OTDR measurement list

Review the list to identify available OTDR measurements prior to retrieving a specific scan output by position number.

The command lists saved OTDR measurements along with the SOR filename associated with each measurement.

Procedure

Use the show hw-module command to display the list of OTDR measurements.

show hw-module slot slot-number otdr scan

Example:

show hw-module slot 3 otdr scan

  # | otdr# | Rx/Tx | Mode | Date/Time       | SOR filename
----+-------+-------+------+-----------------+----------------------------------------
  0 |   1   |  Tx   | AUTO | 20180504-092810 | ncs1001_slot3_otdr1_TX.20180504-092810.sor
  1 |   1   |  Tx   | AUTO | 20180504-114239 | ncs1001_slot3_otdr1_TX.20180504-114239.sor

Example:

Table 2. OTDR measurement list fields
Field	Description
#	Number of OTDR measurements
otdr#	Port where the OTDR measurement was performed
Rx/Tx	Direction of OTDR measurement
Mode	Type of scan, automatic or expert
Date/Time	Date and time of OTDR measurement
SOR filename	Name of the file that contains measurement data

Use the show hw-module command to display scan data for a measurement position.

show hw-module slot slot-number otdr scan position-number

Example:

show hw-module slot 3 otdr scan 0

Measurement on: 20180504-151351
OTDR device number: 1
Scan direction: Tx
Scan mode: Auto
Directory location: /harddisk:/otdr
File name: ncs1001_slot3_otdr1_TX.20180504-151351.sor
Total ORL: 29.86 dB
Distance (estimate): 38.996 km
Total number of event detected: 3

Event# | TYPE         | LOCATION(km) | ACCURACY(m) | MAGNITUDE(dB) | TH-CROSSING
-------+--------------+--------------+-------------+---------------+------------
   0   | LOSS         |    0.000     |    5.62     |    -1.09      | NO
   1   | LOSS         |   23.840     |  114.06     |    -0.44      | NO
   2   | END OF FIBER |   38.996     |  249.00     |               | NO

Example:

Table 3. OTDR scan detail fields
Field	Description
OTDR device number	Port number
Scan direction	Direction of scan
Scan mode	Mode of scan, automatic or expert
Directory location	Location where the SOR file is stored
File name	Name of the SOR file
Total ORL	Optical return loss in dB
Distance (estimate)	Distance in km
Total number of event detected	Events detected during the OTDR measurement
Event#	Event number
TYPE	Event type, such as LOSS or END OF FIBER
LOCATION(km)	Location of the event in the span
ACCURACY(m)	Accuracy of the event location in the span
MAGNITUDE(dB)	Loss magnitude of the event
TH-CROSSING	loss-abs-threshold value

The command output shows the stored OTDR measurements for the selected scan details.

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