Cisco Cisco BPX 8600 Modules Troubleshooting Guide

Introduction
 Prerequisites
      Requirements
      Components Used
      Conventions
 Error Indications
 Error Resolution
 Related Information

This document explains standby Pseudo−Random Bit Sequence (PRBS) errors on the Cisco BPX and
provides an approach to resolve the errors.

There are no specific requirements for this document.

This document is not restricted to specific software and hardware versions.

For more information on document conventions, refer to the Cisco Technical Tips Conventions.

The Cisco BPX has redundant buses for point−to−point links. When a standby Broadband Controller Card
(BCC) is present and you have fully updated the BCC, the Serial Interface Unit (SIU) generates a test pattern
on the inactive bus transmitter. The SIU receives the same pattern on the SIU receiver on the inactive bus. The
standby BCC provides the loopback of the signal.

Standby PRBS errors indicate the failure of a background test of the standby bus. This test sends and receives
a PRBS over the standby circuitry. The test failure can indicate a problem with the reporting card, the
backplane, or the standby BCC. The errors warn that, if a BCC switchover takes place, the card may not be
able to transmit or receive data properly on the backplane.

The resolution of standby PRBS errors is a process of elimination. If multiple cards report the error, the error
can mean that the BCC crosspoint switch is faulty or the configuration was poor. When a single card has