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

Configure OTDR

Updated: July 27, 2026

Want to summarize with AI?

Use this procedure to configure OTDR optical parameters for TX and RX directions after the OTDR card is inserted into Cisco NCS 1001.

Configure OTDR parameters when the default values must be changed for the fiber span.

When the OTDR card is inserted, it has default optical parameters for both the ports and both the TX and RX directions.

Procedure

	1.	Enter configuration mode. Example: `configure`
	2.	Use the hw-module location command to enter OTDR slot configuration mode. Example: `hw-module location 0/RP0/CPU0 slot 2`
	3.	Configure the OTDR parameters for the required port and direction. Configure only the parameter values that must differ from the default values. See OTDR configuration parameters for the parameter descriptions, ranges, and defaults. Example: otdr port 1 direction tx total-loss 200 otdr port 1 direction tx back-scattering -820 otdr port 1 direction tx refractive-index 1498962 otdr port 1 direction tx mode-expert pulse-width 1000 otdr port 1 direction tx mode-expert measure-time 180 otdr port 1 direction tx mode-expert capture-length 80 otdr port 1 direction tx mode-expert capture-offset 0 otdr port 1 direction tx mode-expert fiber-resolution 25 otdr port 1 direction tx mode-expert loss-relative-threshold 20 otdr port 1 direction tx mode-expert reflection-relative-threshold 20 otdr port 1 direction rx total-loss 200 otdr port 1 direction rx mode-expert pulse-width 1000 otdr port 1 direction rx mode-expert measure-time 180 otdr port 1 direction rx mode-expert capture-length 80 otdr port 1 direction rx mode-expert capture-offset 0 otdr port 1 direction rx mode-expert fiber-resolution 25 otdr port 1 direction rx mode-expert loss-relative-threshold 20 otdr port 1 direction rx mode-expert reflection-relative-threshold 20 otdr port 1 orl-abs-threshold 280 otdr port 1 loss-abs-threshold 15 otdr port 1 reflection-abs-threshold -300 commit end
	4.	Commit the configuration and exit configuration mode. Example: `commit end`

The OTDR parameters are configured for the selected port and direction.

OTDR configuration parameters

Use these values when configuring OTDR optical parameters for the selected port and direction.

Table 1. OTDR configuration parameters
Parameter	Description	Range	Default
total-loss (in 0.1 dB)	Loss from the near-end OTDR port to the far-end OTDR port, including span loss and additional EDFA filter loss.	0 to 500	200
back-scattering	Backscattering value in the TX direction.	-100.0 to 0.0	-82.0
refractive-index	Refractive index value in the TX direction.	1.000000 to 2.000000	1.498962
mode-expert pulse-width (ns)	Pulse duration during the measurement.	8 to 100000	1000
mode-expert measure-time (sec)	Time required to perform a complete optical scan.	1 to 360	180
mode-expert capture-length (km)	Distance of the measurement endpoint.	1 to 150	80
mode-expert capture-offset (km)	Start point of the measurement.	0 to 150	0
mode-expert fiber-resolution (m)	Distance between measurement steps.	0 to 100	25
orl-abs-threshold (in 0.1 dB)	Threshold to compare with the ORL measurement returned by the OTDR run.	140 to 400	280
loss-abs-threshold (in 0.1 dB)	Threshold to compare with loss events returned by the OTDR run.	1 to 300	15
reflection-abs-threshold (in 0.1 dB)	Threshold to compare with reflection events returned by the OTDR run.	-500 to 0	-300
loss-sensitivity (in 0.1 dB)	Limit under which the loss is not considered a real loss.	4 to 50	6
reflection-sensitivity (in 0.1 dB)	Limit under which the reflection is not considered a real reflection.	-400 to -140	-300
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.

Note

For back-scattering and refractive-index, Cisco NCS 1001 accepts any value within the defined range. Set the actual value based on the fiber characteristics and optimal values for the specific fiber type in your network.

Display OTDR measurement status

Display OTDR measurement status to confirm whether automatic or expert scans are running, completed, aborted, or unknown.

The command displays a table with status for all the OTDR ports and directions.

Procedure

Use the show hw-module command to display OTDR status for the slot.

Example:

show hw-module slot 2 otdr status
 Automatic Mode 

Wed Oct 16 09:06:46.148 CEST
  Port | Rx/Tx |  Date/Time|     Training |   OTDR Measurement| Next scan (min)
-------+-------+---------------------+--------------------+----------------------+-
   1   |   Tx  |           |     UNKNOWN  |       UNKNOWN     |       0
   1   |   Rx  |           |     UNKNOWN  |       UNKNOWN     |       0
   2   |   Tx  |           |     UNKNOWN  |       UNKNOWN     |       0
   2   |   Rx  |           |     UNKNOWN  |       UNKNOWN     |       0

The next scan is related to the periodic scan. When the periodic scan is not set, the next scan value is 0.
 Expert Mode 
 
Port | Rx/Tx |      Date/Time        |     Training       |   OTDR Measurement
––--------+-------+---------------------+--------------------+-------------------

   1   |   Tx  |   20180503-181159   |     UNKNOWN         | PROGRESS    10%  

   1   |   Rx  |                     |     UNKNOWN         |       UNKNOWN  

   2   |   Tx  |                     |     UNKNOWN         |       UNKNOWN  

   2   |   Rx  |                     |     UNKNOWN         |       UNKNOWN

If periodic scan is not set, the next-scan value is 0.

Need help?

Open a support case

(Requires a Cisco Service Contract)

The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.