Pseudo Random Binary Sequence

Pseudo Random Binary Sequence

The Pseudo Random Binary Sequence (PRBS) feature feature enables data integrity checks between NCS1014 trunk and client links without generating client traffic.

To ensure that the traffic is error-free during link bring up without relying on the peer port, you must enable the PRBS feature on both the transmitting and receiving ports of your NCS 1014 trunk. The transmitting trunk port creates a bit pattern and sends it to the peer NCS 1014 device. The device then confirms if the sent bit pattern is received. The 1.2T card supports PRBS on the ODU4 controller.

You can configure PRBS on the NCS 1014 trunk and client ports of a 1.2T, 2.4T, and 2.4TX cards.

  • Source mode — The NCS 1014 at trunk port generates PRBS signal on the line continuously as per the configured PRBS pattern.

  • Sink mode — The NCS 1014 at trunk port gets locked to the ingress signal according to the configured pattern, analyzes and reports the errors.

  • Source-Sink mode — The NCS 1014 at trunk port acts as both the PRBS transmitter and receiver, that is, it generates PRBS signal as per the configured pattern, and also gets locked to the ingress signal with the same pattern, and reports the errors.

Configure Pseudo Random Binary Sequence

You can configure PRBS on a coherentDSP or Ethernet controller of a 1.2T, 2.4T, or 2.4TXcard. PRBS can also be configured on a ODU controller of the 1.2T card. Before enabling PRBS, the secondary admin state of the controllers must be set to maintenance.

Configure PRBS on CoherentDSP Controller

To configure PRBS on the trunk port of the coherentDSP controller of a 1.2T, 2.4T, or 2.4TX card, use the following configuration commands in the configuration mode:

controller coherentDSP R/S/I/P

secondary-admin-state maintenance

prbs mode {source | sink | source-sink} pattern {pn31 | pn23 | pn15 | pn7}

Example to Configure PRBS on CoherentDSP Controller:

Use the following sample configuration to configure PRBS on trunk ports of a coherentDSP controller:
RP/0/RP0/CPU0:ios(config)#controller CoherentDSP 0/0/0/7
RP/0/RP0/CPU0:ios(config-CoDSP)#secondary-admin-state maintenance
RP/0/RP0/CPU0:ios(config-CoDSP)#prbs mode source-sink pattern pn15
RP/0/RP0/CPU0:ios(config-CoDSP)#commit
Wed Nov 15 18:11:55.450 UTC

Configure PRBS on ODU Controller

You can configure PRBS in the following combinations for an ODU controller on a 1.2T card. The client ports need to have a physical loopback in all the combinations.

  • Near End client and Near End trunk ODU4

  • Near End client and Far End client ODU4

  • Near End client and Far End trunk ODU4

  • Near End trunk and Far End trunk ODU4

To enable PRBS on ODU4 controller's trunk ports of a 1.2T card, use these commands in configuration mode:

controller odu4 R/S/I/P

secondary-admin-state maintenance

opu prbs mode {source | sink | source-sink} pattern {pn31 | pn23 | pn15 | pn7}

Example to Configure PRBS on ODU Controller:

Following is an example to configure PRBS on client ports of an ODU controller of a 1.2T card:

RP/0/RP0/CPU0:ios(config)#controller odu4 0/0/0/4
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#prbs mode source-sink pattern pn23
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#sec-admin-state maintenance
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#commit

Configure PRBS on Ethernet Controller

To configure PRBS on the client ports of an Ethernet controller of the 2.4T and 2.4TX cards, use the following commands in the configuration mode:

controller {fourHundredGigECtrlr} R/S/I/P

secondary-admin-state maintenance

opu prbs mode {source | sink | source-sink} pattern {pn31 | pn23 }

Example to Configure PRBS on Ethernet Controller:

Following is an example to configure PRBS on client ports of an Ethernet controller of a 2.4T card:

RP/0/RP0/CPU0:ios(config)#controller FourHundredGigECtrlr 0/3/0/1 
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#prbs mode source-sink pattern pn31
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#sec-admin-state maintenance
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#commit

Verifying PRBS

You can monitor the status of Pseudo Random Binary Sequence (PRBS) using the following command:

show controllers coherentDSP | ODU4 | fourHundredGigEctrlr R/S/I/P prbs-details

Example to view PRBS details on Ethernet controller

Use the following sample configuration to display PRBS details configured on an Ethernet controller: 

RP/0/RP0/CPU0:ios#show controllers fourHundredGigEctrlr 0/0/0/4
Wed Nov 15 18:39:29.478 UTC
Operational data for interface FourHundredGigECtrlr0/0/0/4:

State:
    Administrative state: enabled
    Operational state: Up
    LED state: Green On
    Maintenance: Enabled
    AINS Soak: None
      Total Duration: 0 hour(s) 0 minute(s)
      Remaining Duration: 0 hour(s) 0 minute(s) 0 second(s)
    PRBS:
      Status: Locked
      Mode: Source-sink
      Pattern: PN23
      Direction: Line
      Framing: Framed
    Laser Squelch: Disabled
    Insert Idle Ingress: Disabled
    Insert Idle Egress: Disabled

Phy:
    Media type: Not known
    Statistics:
        FEC:
            Corrected Codeword Count: 2019127152               Valid: True       Start time: 17:35:46 Wed Nov 15 2023
            Uncorrected Codeword Count: 6                      Valid: True       Start time: 17:35:46 Wed Nov 15 2023
        PCS:
            Total BIP errors: 0                                Valid: True       Start time: 17:35:46 Wed Nov 15 2023
            Total frame errors: 0                              Valid: False      Start time: 17:35:46 Wed Nov 15 2023
            Total Bad SH: 0                                    Valid: False      Start time: 17:35:46 Wed Nov 15 2023

Autonegotiation disabled.

Operational values:
    Speed: 400Gbps
    Duplex: Full Duplex
    Flowcontrol: None
    Loopback: Internal
    BER monitoring:
        Not supported
    Forward error correction: Standard (Reed-Solomon)
    Holdoff Time: 0ms
Example to view PRBS details on CoherentDSP controller

Use the following sample configuration to display PRBS details configured on a coherentDSP controller: 

RP/0/RP0/CPU0:ios#show  controllers coherentDSP 0/0/0/7 prbs-details
Wed Nov 15 18:13:35.210 UTC

----------------------PRBS details------------------
PRBS Test               : Enable
PRBS Mode               : Source-Sink
PRBS Pattern            : PN15
PRBS Status             : Locked
Example to view PRBS details on ODU controller

Use the following sample configuration to display PRBS details configured on an ODU controller where the PRBS status is displayed as Not Applicable, when the mode is Source. 

RP/0/RP0/CPU0:ios#show controllers ODU4 0/3/0/8 prbs-details
Mon Jan 11 05:29:12.436 UTC

 -------------------------PRBS details----------------------------------
PRBS Test                       : Enable
PRBS Mode                       : Source
PRBS Pattern                    : PN7
PRBS Status                     : Not Applicable

---------------------------------------------------

Viewing PRBS Performance Monitoring Parameters

To view the PRBS performance monitoring parameters on a coherentDSP, ODU, or Ethernet controller, use the following command:

show controllers coherentDSP | ODU4 R/S/I/P pm {current | history }{15-min|24-hour} prbs

Following is an example of how to view the cumulative count of PRBS bit errors in the 15-min sampling interval on a CoherentDSP controller: 

RP/0/RP0/CPU0:ios#show controllers coherentDSP 0/0/0/7 pm current 15-min prbs
Wed Nov 15 18:19:10.308 UTC

 PRBS in the current interval [18:15:00 - 18:19:10 Wed Nov 15 2023]

 PRBS current bucket type : Valid

 EBC          : 0           Threshold : 0         TCA(enable)  : NO
 FOUND-COUNT  : 0           Threshold : 0         TCA(enable)  : NO
 LOST-COUNT   : 0           Threshold : 0         TCA(enable)  : NO

 FOUND-AT-TS  : NULL
 LOST-AT-TS   : NULL

 CONFIG-PTRN  : PRBS_PATTERN_PN15
 STATUS       : LOCKED

Last clearing of "show controllers OTU" counters never

Following is an example of how to view PRBS performance monitoring parameters for a 15-minute sampling interval on an ODU controller: 

RP/0/RP0:ios#show controllers ODU4 0/3/0/1 pm current 15-min prbs
Mon Jan 11 00:58:48.327 UTC 
 
PRBS in the current interval [00:45:00 - 00:58:48 Mon Jan 11 2021] 
PRBS current bucket type : Valid 
EBC                      : 40437528165 
FOUND-COUNT              : 1 FOUND-AT-TS : 00:51:22 Mon Jan 11 2021
LOST-COUNT               : 1 LOST-AT-TS  : 00:52:52 Mon Jan 11 2021
CONFIG-PTRN              : PRBS_PATTERN_PN7
Last clearing of "show controllers ODU" counters never

The following tables describes the fields of PRBS PM parameters.

Following is an example of how to view PRBS performance monitoring parameters for a 15-minute sampling interval on an Ethernet controller: 

RP/0/RP0/CPU0:ios#show controllers fourHundredGigEctrlr 0/0/0/4 pm current 15-min prbs
Wed Nov 15 18:48:19.114 UTC

 PRBS in the current interval [18:45:00 - 18:48:19 Wed Nov 15 2023]

 PRBS current bucket type : Valid

 EBC          : 0           Threshold : 0         TCA(enable)  : NO
 FOUND-COUNT  : 0           Threshold : 0         TCA(enable)  : NO
 LOST-COUNT   : 0           Threshold : 0         TCA(enable)  : NO

 FOUND-AT-TS  : NULL
 LOST-AT-TS   : NULL

 CONFIG-PTRN  : PRBS_PATTERN_PN23
 STATUS       : LOCKED

Last clearing of "show controllers ETHERNET" counters never

The following tables describes the fields of PRBS PM parameters.

Table 1. PRBS PM Parameters

PM Parameter

Description

EBC

Cumulative count of PRBS bit errors in the sampling interval (15-minute or 24-hour). PRBS bit errors are accumulated only if PRBS signal is locked.

FOUND-COUNT

Number of state transitions from signal unlocked state to signal locked state in the sampling interval. If state change is not observed in the interval, the count is 0.

LOST-COUNT

Number of state transitions from signal locked state to signal unlocked state in the sampling interval. If state change is not observed in the interval, the count is 0.

FOUND-AT-TS

Latest timestamp when the PRBS state moves from unlocked state to locked state in the sampling interval. If state change is not observed in the interval, the value is null.

CONFIG-PTRN

Configured PRBS pattern on the port.

STATUS

Displays the PRBS status.

Clearing Bit Errors and Lock Time for PRBS

Lock time is the time that is elapsed since the last PRBS lock is detected.

The following sample shows that bit errors are observed during the PRBS test: 


RP/0/RP0/CPU0:ios#show controllers odu4 0/2/0/5 prbs-details
Fri Nov 13 03:21:44.191 UTC

-------------------------PRBS details----------------------------------
PRBS Test : Enable
PRBS Mode : Source-Sink
PRBS Pattern : INVERTED PN31
PRBS Status : Locked
PRBS Direction : Line
PRBS Lock Time(in seconds) : 28
PRBS Bit Errors : 23776

---------------------------------------------------

To clear the lock time and bit errors before the PRBS test, use the clear command: 


RP/0/RP0/CPU0:ios#clear controller odu4 0/2/0/5 prbs-details
Fri Nov 13 03:21:50.726 UTC
PRBS bit errors cleared

The following sample displays the bit errors and lock time are removed.


RP/0/RP0/CPU0:ios#show controllers odu4 0/2/0/5 prbs-details
Fri Nov 14 03:21:44.191 UTC
-------------------------PRBS details----------------------------------
PRBS Test : Enable
PRBS Mode : Source-Sink
PRBS Pattern : INVERTED PN31
PRBS Status : Locked
PRBS Direction : Line
PRBS Lock Time(in seconds) : 2
PRBS Bit Errors : 0

Trunk PRBS

NCS 1014 trunk port supports the following PRBS patterns:

  • PRBS31 — Sequence length is from 2^31 -1 bits.

  • PRBS23 — Sequence length is from 2^23 -1 bits.

  • PRBS15 — Sequence length is from 2^15 -1 bits.

  • PRBS11 —Sequence length is from 2^11 -1 bits.

  • PRBS7 —Sequence length is from 2^7 -1 bits.


Tip

We recommend that for higher datarates like 100G and 400G:

  • use high sequence length PRBS patterns and

  • use PRBS inverted pattern.

Note

Interoperability for ethernet PRBS PN23 pattern is not supported in the 2.4T and 2.4TX cards.


Note

In case of muxponder configuration, PRBS is not supported on the split ports of the 2.4TX card.

Configuring Trunk PRBS on NCS1K4-2.4T-K9

Use the following sample configuration to configure PRBS trunk mode on the NCS1K4-2.4T-K9:

RP/0/RP0/CPU0:ios(config)#controller CoherentDSP0/0/0/7
RP/0/RP0/CPU0:ios(config-CoDSP)#secondary-admin-state maintenance
RP/0/RP0/CPU0:ios(config-CoDSP)#prbs mode source-sink pattern pn15
RP/0/RP0/CPU0:ios(config-CoDSP)#commit
Wed Nov 15 18:11:55.450 UTC
Table 2. Feature History

Feature Name

Release Information

Description

Cumulative PRBS on CoherentDSP controllers

Cisco IOS XR Release 24.3.1

The cumulative PRBS (Pseudo-Random Binary Sequence) on CoherentDSP controllers enhances troubleshooting capabilities between the trunk ports.

Show coherentDSP R/S/I/P prbs-details command output now includes the newly supported fields.

Use the following sample configuration to display PRBS details: 

RP/0/RP0/CPU0:ios#show controllers coherentDSP 0/0/0/7 prbs-details
Wed Nov 15 18:13:35.210 UTC

----------------------PRBS details------------------
PRBS Test               : Enable
PRBS Mode               : Source-Sink
PRBS Pattern            : PN15
PRBS Status             : Locked
PRBS Lock Time(in seconds)      : 37
PRBS Bit Errors                 : 0
PRBS Found Count                : 1
PRBS Lost Count                 : 0
PRBS Configured Time            : 11 Feb 00:20:43 (719 seconds elapsed)
PRBS First Lock Established Time: 11 Feb 00:32:05 (37 seconds elapsed)
Result Summary                  : PASS

The Result Summary will display PASS if the PRBS bit errors are 0 and the PRBS elapsed lock time is equal to the elapsed first lock established time.

Use this command to clear the counters .

clear controller coherentDSP 0/0/0/7 prbs-details

Use the following sample configuration to display cumulative count of PRBS bit errors in the 15-min sampling interval: 

RP/0/RP0/CPU0:ios#show controllers coherentDSP 0/0/0/7 pm current 15-min prbs
Wed Nov 15 18:19:10.308 UTC

 PRBS in the current interval [18:15:00 - 18:19:10 Wed Nov 15 2023]

 PRBS current bucket type : Valid

 EBC          : 0           Threshold : 0         TCA(enable)  : NO
 FOUND-COUNT  : 0           Threshold : 0         TCA(enable)  : NO
 LOST-COUNT   : 0           Threshold : 0         TCA(enable)  : NO

 FOUND-AT-TS  : NULL
 LOST-AT-TS   : NULL

 CONFIG-PTRN  : PRBS_PATTERN_PN15
 STATUS       : LOCKED

Last clearing of "show controllers OTU" counters never

Client PRBS

NCS 1014 client port supports the following PRBS patterns:

  • PRBS31 — Sequence length is from 2^31 -1 bits

  • PRBS23 — Sequence length is from 2^23 -1 bits

Configuring Client PRBS on NCS1K4-2.4T-K9

Use the following sample configuration to configure PRBS client mode on the NCS1K4-2.4T-K9:

RP/0/RP0/CPU0:ios(config)#controller fourHundredGigECtrlr 0/0/0/4
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#prbs mode source-sink pattern pn23
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#sec-admin-state maintenance
RP/0/RP0/CPU0:ios(config-eth-ctrlr)#commit

Use the following sample configuration to display four hundred gigabit client controllers details:

RP/0/RP0/CPU0:ios#show controllers fourHundredGigEctrlr 0/0/0/4
Wed Nov 15 18:39:29.478 UTC
Operational data for interface FourHundredGigECtrlr0/0/0/4:

State:
    Administrative state: enabled
    Operational state: Up
    LED state: Green On
    Maintenance: Enabled
    AINS Soak: None
      Total Duration: 0 hour(s) 0 minute(s)
      Remaining Duration: 0 hour(s) 0 minute(s) 0 second(s)
    PRBS:
      Status: Locked
      Mode: Source-sink
      Pattern: PN23
      Direction: Line
      Framing: Framed
    Laser Squelch: Disabled
    Insert Idle Ingress: Disabled
    Insert Idle Egress: Disabled

Phy:
    Media type: Not known
    Statistics:
        FEC:
            Corrected Codeword Count: 2019127152               Valid: True       Start time: 17:35:46 Wed Nov 15 2023
            Uncorrected Codeword Count: 6                      Valid: True       Start time: 17:35:46 Wed Nov 15 2023
        PCS:
            Total BIP errors: 0                                Valid: True       Start time: 17:35:46 Wed Nov 15 2023
            Total frame errors: 0                              Valid: False      Start time: 17:35:46 Wed Nov 15 2023
            Total Bad SH: 0                                    Valid: False      Start time: 17:35:46 Wed Nov 15 2023

Autonegotiation disabled.

Operational values:
    Speed: 400Gbps
    Duplex: Full Duplex
    Flowcontrol: None
    Loopback: Internal
    BER monitoring:
        Not supported
    Forward error correction: Standard (Reed-Solomon)
    Holdoff Time: 0ms

Use the following sample configuration to display four hundred gigabit client controller PRBS bit errors in the 15-min sampling interval: 

RP/0/RP0/CPU0:ios#show controllers fourHundredGigEctrlr 0/0/0/4 pm current 15-min prbs
Wed Nov 15 18:48:19.114 UTC

 PRBS in the current interval [18:45:00 - 18:48:19 Wed Nov 15 2023]

 PRBS current bucket type : Valid

 EBC          : 0           Threshold : 0         TCA(enable)  : NO
 FOUND-COUNT  : 0           Threshold : 0         TCA(enable)  : NO
 LOST-COUNT   : 0           Threshold : 0         TCA(enable)  : NO

 FOUND-AT-TS  : NULL
 LOST-AT-TS   : NULL

 CONFIG-PTRN  : PRBS_PATTERN_PN23
 STATUS       : LOCKED

Last clearing of "show controllers ETHERNET" counters never