Configure OTDR Module

This chapter describes how to configure the Optical Time Domain Reflectometer (OTDR) module.


Note

When you plan to replace a configured optical module with a different type of optical module, you must clear the configurations of the old module before you install the new module. For example, when replacing a configured EDFA module with an OTDR in the same slot, clear the EDFA configurations.

In general, configurations in a card equipped in an NCS 1001 slot include:

  • Card configuration—hw-module parameters configuration related to the slot S where the card is equipped

  • OTS controller configurations

  • Optics controller configurations—only for EDFA cards

The following commands clear the configurations in the previous card.

  1. no hw-module location 0/RP0/CPU0 slot <S>

    Clear the card parameters configuration.

  2. no controller ots Rack/Slot/Instance/Port

    Clear each OTS controller configuration.

  3. no controller optics Rack/Slot/Instance/Port

    (Optional) Clear the controller optics configurations. This must be done only if the card previously equipped in slot S was an EDFA.

OTDR

The optical Time Domain Reflectometer (OTDR) is a line card supported in NCS 1001. The line card contains 2x bidirectional OTDRs and 2x filter that combines C-band, OSC, and OTDR filters and splits OSC and OTDR. Each internal OTDR can perform measurements on both TX and RX fibers by using an internal optical switch. The OTDR line card is connected to the OSC port on the optical amplifier. The OTDR measurement is available in a .SOR file and it can be exported from NCS 1001 using SCP, TFTP, and SFTP. The OTDR line card can be inserted in any slot of NCS 1001.

Figure 1. Front View of OTDR Card

1

OTDR1 interface

2

LED status

3

OTDR2 interface

The following table lists the logical ports (OTS controller ports) that are associated with the physical ports in the OTDR card.

Table 1. OTDR Physical Ports and the Associated Logical Ports

OTDR Ports

Logical Ports Corresponding to the Ports

C-Band-1 RX

controller OTS 0/slot/0/0

COM1 (RX, TX)

controller OTS 0/slot/0/1

OSC1 (RX, TX)

controller OTS 0/slot/0/2

C-Band-2 RX

controller OTS 0/slot/0/3

COM2 (RX, TX)

controller OTS 0/slot/0/4

OSC2 (RX, TX)

controller OTS 0/slot/0/5

You can also view the logical ports details available in the table Table 1 using the CLI command. See View the Logical Ports and the Photodiode Power Levels.

The OTDR line card allows the user to perform the following:

  • Provides information about basic characteristics of the optical fiber among optical nodes, such as Insertion Loss and concentrate point of reflection.

  • Inspects the transmission fiber.

  • Identifies discontinuities or defects on the fiber.

  • Measures the distance and magnitude of defects like insertion loss, reflection loss, and so on.

  • Improves scan performance using specific scan parameters targeted on the characteristics of the fiber plant such as span length, reflection contributions, and major events.


Note

When an EDFA module is connected to the OTDR module without an OSC channel between them, an LOS-P alarm is raised on the OTS 0/x/0/2 port of the EDFA module. To suppress this alarm and resume normal OTDR operation, we recommend you perform one of the following configurations on the port 0/x/0/2 of the EDFA module:

  • Configure the OTS controller to be under maintenance.

    Example:

    RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config)#controller ots 0/3/0/2
RP/0/RP0/CPU0:ios(config-ots)#sec-admin-state maintenance
RP/0/RP0/CPU0:ios(config-ots)#commit

  • Shut down the EDFA port in receive direction.

    Example:

    RP/0/RP0/CPU0:ios#configure
RP/0/RP0/CPU0:ios(config)#controller ots 0/3/0/2
RP/0/RP0/CPU0:ios(config-ots)#rx-enable 0
RP/0/RP0/CPU0:ios(config-ots)#commit

OTDR Modes

OTDR can be configured in two modes.

  • Auto-This mode has two internal phases: Training and Measurement. These two phases are fully automated and proceed in sequence. The training phase has two internal steps. The first step measures the Optical Return Loss (ORL) and the second step prepares internal parameters for OTDR measurement. The actual OTDR measurement starts after the training phase.

  • Expert-In this mode, the user must configure all the OTDR scan parameters with the proper values required by OTDR measurement. Automatic adjustments are not performed in expert mode configuration. There is no training phase in this mode. There is no prerequisite to run OTDR scan in expert mode apart from proper configuration.

Limitations of OTDR

  • When NCS 1001 uses the OTDR line card, the OSC channel is on 1610 nm, and OTDR is on 1518 nm.

  • OTDR supports up to 20 dB span loss or 100 km length of fiber.

  • It is not recommended to start OTDR measurement simultaneously from two different nodes; the results and graph will not be valid.

  • OTDR measurement performed in the presence of the OTDR-HIGH-REFLECTION alarm (reflections roughly greater than -25dB) may provide a low event accuracy.

  • OTDR graph may be truncated if the measurements are performed on a fiber spool with the following length.

    • 1.00km to 1.05km

    • 25.0km to 25.6km

    • 80.0km to 83.9km

  • OTDR can support up to -14 dB of reflection. OTDR-HIGH-REFLECTION alarm is raised when R(dB) – 2*NL(dB) > -20 dB where R is the reflectivity and NL is the loss.

Cabling Considerations for Terminal Node

In the terminal node configuration, EDFA and OTDR line cards are plugged into the same NCS 1001 system. The filter on OTDR card will combine OSC SFP signal from EDFA port with OTDR and feed into OSC input of EDFA card.

The sequence of fiber connection for port 1 is the following:

  1. Connect a LC/LC fiber from OTDR COM TX port to EDFA OSC RX port

  2. Connect a LC/LC fiber from EDFA OSC TX port to OTDR COM RX port

  3. Connect a LC/LC fiber from OTDR OSC TX port to pluggable RX port inserted into EDFA

  4. Connect a LC/LC fiber from pluggable TX port inserted into EDFA to OTDR OSC RX port

Repeat the same sequence to connect the second OTDR port if required.

Figure 2. Cabling for Terminal Configuration with One EDFA Module
Figure 3. Cabling for Terminal Configuration with Two EDFA Modules

Cabling Considerations for ILA Node

In the ILA node configuration, only one OTDR card is required to support both the directions of ILA node. Two EDFA cards and a single OTDR line card are plugged into the same NCS 1001 system. It is recommended to connect the OTDR port 1 to EDFA in slot 1 and the OTDR port 2 to EDFA in slot 3.

The sequence of fiber connection is the following:

  1. Connect a LC/LC fiber from OTDR port 1 COM TX port to fiber span Line TX that is facing EDFA slot 1.

  2. Connect a LC/LC fiber from EDFA slot 1 port COM TX to C-band 1 RX port.

  3. Connect a LC/LC fiber from OTDR OSC TX port 1 to pluggable RX port inserted into EDFA slot 1.

  4. Connect a LC/LC fiber from OSC pluggable TX port inserted into EDFA slot 1 to OTDR OSC RX port 1.

  5. Connect a LC/LC fiber from EDFA slot 1 port OSC TX to OTDR COM RX port 1.

  6. Connect a LC/LC fiber from OTDR port 2 COM TX port to fiber span Line TX that is facing EDFA slot 3.

  7. Connect a LC/LC fiber from EDFA slot 3 port COM TX to C-band 2 RX port.

  8. Connect a LC/LC fiber from OTDR OSC TX port 2 to OSC pluggable RX port inserted into EDFA slot 3.

  9. Connect a LC/LC fiber from OSC pluggable TX port inserted into EDFA slot 3 to OTDR OSC RX port 2.

  10. Connect a LC/LC fiber from from EDFA slot 3 port OSC TX to OTDR COM RX port 2.

Figure 4. Cabling for ILA Configuration
Cabling for ILA Configuration

Cabling for ILA Configuration with 15216-FLD-OSC

The sequence of fiber connection is the following:

  1. Connect a LC/LC fiber from RX-span 2 to LINE RX port of EDFA slot 1.

  2. Connect a LC/LC fiber from COM TX port of EDFA slot 1 to COM RX port of 15216-FLD-OSC position 1.

  3. Connect a LC/LC fiber from TX-span 1 to LINE TX port of 15216-FLD-OSC position 1.

  4. Connect a LC/LC fiber from OSC pluggable TX port inserted into EDFA slot 1 to OSC RX port of 15216-FLD-OSC position 1.

  5. Connect a LC/LC fiber from OSC TX port of EDFA slot 1 to OSC pluggable RX port inserted into EDFA slot 3.

  6. Connect a LC/LC fiber from OSC TX port of EDFA slot 3 to OSC pluggable RX port inserted into EDFA slot 1.

  7. Connect a LC/LC fiber from RX-span 1 to LINE RX port of EDFA slot 3.

  8. Connect a LC/LC fiber from COM TX port of EDFA slot 3 to COM RX port of 15216-FLD-OSC position 2.

  9. Connect a LC/LC fiber from TX-span 2 to LINE TX port of 15216-FLD-OSC position 2.

  10. Connect a LC/LC fiber from OSC pluggable TX port inserted into EDFA slot 3 to OSC RX port of 15216-FLD-OSC position 2.

Figure 5. Cabling for ILA Configuration with 15216-FLD-OSC

The usage of NCS1K-OTDR module replaces the need of 15216-FLD-OSC module as recommended in the ILA configuration.

Configure OTDR

When the OTDR card is inserted, it has a set of default optical parameters for both ports and both directions. The default parameters are the same for both ports in TX and RX directions.

configure

hw-module location 0/RP0/CPU0 slot slot-number

otdr port port-number direction tx total-loss value

otdr port port-number direction tx back-scattering value

otdr port port-number direction tx refractive-index value

otdr port port-number direction tx mode-expert pulse-width value

otdr port port-number direction tx mode-expert measure-time value

otdr port port-number direction tx mode-expert capture-length value

otdr port port-number direction tx mode-expert capture-offset value

otdr port port-number direction tx mode-expert fiber-resolution value

otdr port port-number direction rx total-loss value

otdr port port-number direction rx mode-expert pulse-width value

otdr port port-number direction rx mode-expert measure-time value

otdr port port-number direction rx mode-expert capture-length value

otdr port port-number direction rx mode-expert capture-offset value

otdr port port-number direction rx mode-expert fiber-resolution value

otdr port port-number orl-abs-threshold value

otdr port port-number loss-abs-threshold value

otdr port port-number reflection-abs-threshold value

commit

end

Example


configure
hw-module location 0/RP0/CPU0 slot 2
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 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 orl-abs-threshold 280
otdr port 1 loss-abs-threshold 15
otdr port 1 reflection-abs-threshold -300
commit
end

OTDR Configuration Parameters

Table 2. OTDR Configuration Parameters

Parameter

Description

Range

Default

total-loss (in 0.1dB)

Loss from the near end OTDR port to far end OTDR port including span loss and additional EDFA filter loss.

+0 to +500

200

back-scattering

The back scattering value in TX direction.

–100.0 to 0.0

Note

 

NCS 1001 SW accepts any value within the defined range. You shall set actual back scattering value depending on the fiber characteristics.

–82.0

Note

 

Default value fits most fiber types. You may adjust the value based on the optimal values for the specific fiber type in your network.

refractive-index

The refractive index value in TX direction.

1.000000 to 2.000000

Note

 

NCS 1001 SW accepts any value within the defined range. You shall set actual refractive index value depending on the fiber characteristics.

1.498962

Note

 

Default value fits most fiber types. You may adjust the value based on the optimal values for the specific fiber type in your network.

mode-expert pulse-width (in ns)

Pulse duration during the measurement.

8 to 100000

1000

mode-expert measure-time (in sec)

Time required to perform a complete optical scan.

0 to 360

180

mode-expert capture-length (in km)

Distance of end point of the measure.

0 to 150

80

mode-expert capture-offset (in km)

Start point.

0 to 150

0

mode-expert fiber-resolution (in m)

Distance from measurement steps.

0 to 100

25

orl-abs-threshold (in 0.1dB)

Threshold to compare with the ORL measurement returned by OTDR run.

+140 to +400

280

loss-abs-threshold (in 0.1dB)

Threshold to compare with the loss events returned by OTDR run.

+1 to +300

15

reflection-abs-threshold (in 0.1dB)

Threshold to compare with the reflection events returned by OTDR run.

–500 to 0

–300

loss-sensitivity (in 0.1dB)

Limit under which the loss is not considered as a real loss.

+4 to +50

6

reflection-sensitivity (in 0.1dB)

Limit under which the reflection is not considered as a real reflection.

–400 to –140

–300

Display Status of OTDR Measurement

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

show hw-module slot slot-number otdr status

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

Configure OTDR in Automatic Mode

The following parameters must be configured to have correct OTDR measurement in automatic mode. The default values for these parameters are provided by this configuration.

configure

hw-module location 0/RP0/CPU0 slot slot-number otdr port port-number direction direction mode-auto

loss-sensitivity value

reflection-sensitivity value

total-loss value

commit

end

OTDR Configuration Parameters in Automatic Mode

Table 3. OTDR Configuration Parameters in Automatic Mode

Parameter

Description

Range

Default

loss-sensitivity (in 0.1dB)

Limit under which the loss is not considered as a real loss.

+4 to +50

6

reflection-sensitivity (in 0.1dB)

Limit under which the reflection is not considered as a real reflection.

-400 to -140

-300

total-loss (in 0.1dB)

Loss from the near end OTDR port to far end OTDR port including span loss and additional EDFA filter loss.

+0 to +500

200

Start OTDR Measurement in Automatic Mode

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

Example

The following example starts the OTDR measurement in automatic mode in TX direction.


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

The user receives a message as "Otdr action will continue in the background". To see the status of OTDR measurement, use the show hw-module slot slot-number otdr status command.

Configure OTDR in Expert Mode

configure

hw-module location 0/RP0/CPU0 slot slot-number otdr port port-number direction direction mode-expert

capture-length value

capture-offset value

fiber-resolution value

loss-sensitivity value

measure-time value

pulse-width value

reflection-sensitivity value

span-length value

commit

end

Examples

The following samples provide a guideline to configure OTDR in expert mode in certain typical cases with a varying span-length parameter. The configuration might need to be modified depending on the fiber status in the field.

Sample configuration for fiber span 1 km:

Sample configuration for fiber span 25 km:


configure
hw-module location 0/RP0/CPU0 slot 2
otdr port 1 direction tx mode-expert pulse-width 100
otdr port 1 direction tx mode-expert span-length 25
otdr port 1 direction tx mode-expert measure-time 180
otdr port 1 direction tx mode-expert capture-length 25
otdr port 1 direction tx mode-expert capture-offset 0
otdr port 1 direction tx mode-expert fiber-resolution 5
otdr port 1 direction tx mode-expert loss-sensitivity 6
otdr port 1 direction tx mode-expert reflection-sensitivity -300

Sample configuration for fiber span 80 km:


configure
hw-module location 0/RP0/CPU0 slot 2
otdr port 1 direction tx mode-expert pulse-width 1000
otdr port 1 direction tx mode-expert span-length 80
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 250
otdr port 1 direction tx mode-expert loss-sensitivity 15
otdr port 1 direction tx mode-expert reflection-sensitivity -300

Sample configuration for fiber span 100 km:


configure
hw-module location 0/RP0/CPU0 slot 2
otdr port 1 direction tx mode-expert pulse-width 7000
otdr port 1 direction tx mode-expert span-length 100
otdr port 1 direction tx mode-expert measure-time 180
otdr port 1 direction tx mode-expert capture-length 100
otdr port 1 direction tx mode-expert capture-offset 0
otdr port 1 direction tx mode-expert fiber-resolution 50
otdr port 1 direction tx mode-expert loss-sensitivity 15
otdr port 1 direction tx mode-expert reflection-sensitivity -300

OTDR Configuration Parameters in Expert Mode

Table 4. OTDR Configuration Parameters in Expert Mode

Parameter

Description

Range

Default

capture-length (in km)

Distance of end point of the measure.

0 to 150

100

capture-offset (in km)

Start point.

0 to 150

0

fiber-resolution (in m)

Distance from measurement steps.

0 to 100

25

loss-sensitivity (in 0.1dB)

Limit under which the loss is not considered as a real loss.

+4 to +50

6

measure-time (in sec)

Time required to perform the complete optical scan.

0 to 360

180

pulse-width (in ns)

Pulse duration during the measurement.

8 to 100000

1000

reflection-sensitivity (in 0.1dB)

Limit under which the reflection is not considered as a real reflection.

-400 to -140

-300

span-length (in km)

Length of span.

0 to 150

100

Start OTDR Measurement in Expert Mode

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

Example

The following example starts the OTDR measurement in expert mode in TX direction.


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

The user receives a message as "Otdr action will continue in the background". To see the status of OTDR measurement, use the show hw-module slot slot-number otdr status command.

Display List of OTDR Measurements

show hw-module slot slot-number otdr scan

Example

The following example shows the list of OTDR measurements.


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

The following table describes the significant fields shown in the above example.

Field

Description

#

Number of OTDR measurements.

otdr#

Port where OTDR measurement is done.

Rx/Tx

Direction of OTDR measurement.

Mode

Type of scan (auto or expert).

Date/Time

Date and time of OTDR measurement.

SOR filename

Number of files with measurement data.

The following example shows data for OTDR measurement stored in position number 0.


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

The following table describes the significant fields shown in the above example.

Field

Description

OTDR device number

Port number.

Scan direction

Direction of scan.

Scan mode

Mode of scan (auto or expert).

Directory location

Location where the SOR file is stored.

File name

Name of SOR file.

Total ORL

Optical return loss in dB.

Distance (estimate)

Distance in km.

Total number of event detected

Event detected during OTDR measurement.

Event#

Number of events.

TYPE

Type of event if the event is a LOSS or END of Fiber.

LOCATION(km)

Location where the event is into the span.

ACCURACY(m)

Accuracy where the event is into the span.

MAGNITUDE(dB)

Magnitude LOSS of event.

TH-CROSSING

loss-abs-threshold value.

Stop OTDR Measurement

Use this command to stop the OTDR measurement in automatic and expert modes.

hw-module slot slot-number otdr port port-number scan abort

Example

The following command displays the status of OTDR measurement in automatic mode after the cancel operation.

show hw-module slot 3 otdr status 

Port |   Rx/Tx |      Date/Time     |     Training  |   OTDR Measurement|Next scan (min)
-------+-------+---------------------+--------------------+----------------------+--------
   1   |  Tx   |   20190927-102727  |     ABORTED   |      UNKNOWN      |    0

The following command displays the status of OTDR measurement in expert mode after the cancel operation.

show hw-module slot 3 otdr status 

Port | Rx/Tx |      Date/Time        |     Training     |   OTDR Measurement
     -------+-------+---------------------+--------------------+-------------------

   1   |   Tx  |   20180503-181159   | UNKNOWN          |      ABORTED

View the Logical Ports and the Photodiode Power Levels

Use the command show controllers otssummary to display the power values of the photodiodes and the logical ports associated with the physical ports of the OTDR module.

Example: 

RP/0/RP0/CPU0:IOS#show controllers ots 0/2/0/*  summary
Tue Jan 23 13:49:41.604 CET

Port         Type   Status   TX Power   TX Total Power  RX Power  RX Total Power  RX Voa Attenuation   TX Voa Attenuation   Ampli Gain     Ampli Tilt
                              (dBm)     (dBm)            (dBm)     (dBm)               (dBm)            (dBm)                             
 ----                ----    ------     -----------      --------   ----------      ---------------   ------------------     -------------   ----------     
Ots0_2_0_0   Com    N/A      -40.00     Unavailable      -40.00    Unavailable       Unavailable        Unavailable         Unavailable    Unavailable
Ots0_2_0_1   Com    N/A       0.60      Unavailable      -16.60    Unavailable       Unavailable        Unavailable         Unavailable    Unavailable
Ots0_2_0_2   Osc    N/A      -17.60     Unavailable       1.30     Unavailable       Unavailable        Unavailable         Unavailable    Unavailable
Ots0_2_0_3   Com    N/A      -40.00     Unavailable      -40.00    Unavailable       Unavailable        Unavailable         Unavailable    Unavailable
Ots0_2_0_4   Com    N/A       0.20      Unavailable      -22.20    Unavailable       Unavailable        Unavailable         Unavailable    Unavailable
Ots0_2_0_5   Osc    N/A      -23.60     Unavailable       1.30     Unavailable       Unavailable        Unavailable         Unavailable    Unavailable

Note

The parameters such as Status, RX Total power, TX Total power, RX Attenuation, TX Attenuation, Amplifier Gain, and Amplifier Tilt on each of the corresponding OTS controller are not available for the OTDR card.