Token Ring

Document ID: 12267

Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Abnormal Conditions
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Introduction

This document provides explanations of the Ring Status messages sent by a Token Ring Interface (TI) chipset when it detects abnormal states or conditions.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

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

Conventions

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

Abnormal Conditions

When a TI detects an abnormal condition of some kind, a Ring Status message is reported by the TI chipset. This message is then forwarded to the system code by the interface, where it is reported on the console as appropriate. These are the different conditions that can be reported:

• Signal Loss—Loss of signal on the ring has been detected by the interface. This can happen in a number of situations, but the most likely one is that another station has just inserted. This typically causes a disruption in service that is reported as Signal Loss.

• Hard Error—A significant problem has occurred to the ring that prevents the transmission of data. The report of this error indicates that the interface is currently either transmitting or receiving beacon frames from the ring.

• Soft Error—The interface has transmitted a Report Error MAC frame. These frames are used to report these kinds of errors:

  • Line Error (code violation, token code violation, or cyclic redundancy check [CRC] violation)

  • Burst Error

  • MAC AC Set Error

  • Lost Frame Error

  • Frame Copied

  • Receiver Congestion

  • Token Error

  For more detail on these errors, refer to the 802.5 standard.

• Ring Beacon—The interface is transmitting beacon frames.

• Wire Fault—The interface has detected an open or short circuit in the lobe data path. This data path starts at the edge of the chipset and includes the token ring transition cable and any other cabling to the connection on the Multi-Station Access Unit.

• HW Removal—The interface has detected an internal error that prevents it from properly participating in ring management. It has removed itself automatically from the ring. This generally indicates a hardware problem.

• Remote Removal—The interface has received a Remove Ring Station MAC frame. The interface has removed itself from the ring.

• Counter Overflow—The chipset is indicating that an internal counter is close to reaching its maximum value. The Token Ring monitor firmware will automatically read the counter and clear this condition.

• Only Station—The interface has detected that it is the only interface connected and inserted into the ring.

• Ring Recovery—The interface is either transmitting or receiving Claim Token MAC frames. This condition is cleared when an Active Monitor has been determined and it transmits a Ring Purge MAC frame.

A soft error report message is printed by the system each time the Token Ring interface chipset sends a Soft Error Report Frame. Soft errors are conditions that temporarily degrade ring performance by requiring data packets to be transmitted more than once. These errors are reported by the station detecting the error and not necessarily by the station causing the error.

A receiver congestion error is a type of soft error. This error is an indication that a station saw a packet addressed to it, but did not have any buffers available to copy the packet. This is probably a very common error for a station that is a focal point for traffic (such as a router or a bridge).

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