Configuration Guide for Cisco NCS 1014, IOS XR Releases 26.x.x

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Trunk PRBS

Updated: June 18, 2026

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This section explains the trunk PRBS feature for NCS 1014, including supported PRBS patterns, typical use cases, and interoperability considerations.

Table 1. 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.

The trunk PRBS feature performs data integrity checks between trunk links without generating actual client traffic.

NCS 1014 trunk port supports these 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.

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

Tip

It is recommended to use these patterns for higher datarates like 100G and 400G:

  • high sequence length PRBS patterns

  • PRBS inverted pattern

Note

The ethernet PRBS PN23 pattern interoperability is not supported on the 2.4T and 2.4TX cards.

Configure the trunk PRBS

Use this task to configure PRBS trunk mode on the NCS1K4-2.4T-K9 or NCS1K14-2.4T-A-K9 card.

Procedure

1.

Run the controller coherentDSP R/S/I/P command to enter the coherentDSP controller configuration mode.

Example:


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
2.

Run the show controllers coherentDSP R/S/I/P prbs-details command to display PRBS details configured on a coherentDSP controller.

Example:

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.
3.

Run the clear controllers coherentDSP R/S/I/P prbs-details command to clear the counters.

Example:

clear controller coherentDSP 0/0/0/7 prbs-detailsentDSP
4.

Run the show controllers coherentDSP R/S/I/P prbs-details command to display cumulative count of PRBS bit errors in the 15-min sampling interval.

Example:

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