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Cisco IGX 8400 Series Switches

UXM Comm Fail Errors

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Document ID: 17718


Contents

Introduction
Prerequisites
      Requirements
      Components Used
      Conventions
Error Definition
Error Example
Troubleshooting
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Introduction

This document discusses Universal Switching Module (UXM) Comm Fail errors.

Prerequisites

Requirements

There are no specific requirements for this document.

Components Used

The information in this document applies to the Cisco IGX™ UXM with OC3, T3, E3, T1, and E1 back cards.

Conventions

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

Error Definition

The UXM logs a Comm Fail error when the communication failure test fails. The IGX network processor module (NPM) uses a Comm Fail test to verify whether a trunk can be used for communication between nodes on the same trunk.

The communication failure test runs independently on each UXM trunk. Use the SuperUser-level cnfnodeparm command to configure the test interval and timeout parameters. The communication failure is initiated by the NPM, which sends a packet or stream of packets that are filled with a test pattern over the target trunk to the distant-end NPM. Depending upon test results, these events can occur:

  • If the packet is correctly received by the distant-end NPM, then it responds with an acknowledgment over the target trunk to the originating NPM.

  • If the originating NPM receives the acknowledgment that contains correct information about the node number and trunk number that matches the local topology map, then the communication failure test passes.

  • If the originating NPM does not receive the acknowledgment within a timeout period, then the communication failure test is attempted again.

  • If retries fail, then the trunk fails the communication failure test. The originating NPM then declares the trunk in Comm Fail. A Comm Fail error is an integrated alarm. A trunk that is in Comm Fail may reroute all connections, depending upon the Enable Rrt setting in the on Comm Fail parameter of the cnfnodeparm command.

  • If a trunk is in Comm Fail, then the test must pass at both ends before the failure clears.

Do not confuse the Comm Fail test with the communication break (Comm Break) test. The Comm Break test is used for nodes that are unable to communicate with each other and that seek to reestablish communication. A Comm Fail could result in a Comm Break between network nodes. Issue the cnfnodeparm command to set these parameters, to configure the Comm Fail test:

Parameter

Description

Network Timeout Period

Amount of time (in milliseconds) that the originating NPM waits for an acknowledgment from the distant-end NPM.

Num Blind Timeouts

The number of times that the originating NPM will send the Comm Fail test pattern to the target NPM before the Comm Fail test is failed.

Comm Fail Interval

Comm Fail test cycle time for all trunks on the node. The unit of measure is in milliseconds. A cycle time of five minutes for five trunks produces a Comm Fail test every one minute.

Comm Fail Multiplier

Trunks that are not in Comm Fail will be tested every Comm Failure Interval and Comm Failure Multiplier. Trunks that are in Comm Fail will be tested every Comm Fail Interval. The unit of measurement is one.

Comm Fail Delay

Amount of delay between successive Comm Fail tests. Allows real-time processing to improve after a processor card switchover or node rebuild. The unit of measurement is in milliseconds.

Note: The default values for the Comm Fail test parameters are optimized to ensure node and network function. Do not change values until you have first verified them in a laboratory environment.

Issue the cnfcftst command to configure the test pattern that is used by the NPM for the Comm Fail test. If you change the test pattern, you can detect trunk problems that are pattern-sensitive.

Comm Fail and Comm Break errors can have these causes:

  • Carrier and cable problems

  • Trunk card malfunction

  • Processor card malfunction

  • Hardware configuration mismatches

Error Example

The likely location of equipment errors is highlighted in yellow in this diagram:

Comm Fail

uxm_comm_fail_errors.gif

  • NT—Network Termination

  • MUX—The Multiplexer in the Telco line path.

  • Rx—Receive

  • Tx—Transmit

Troubleshooting

Issue the Service-level on1 command and verify that Comm Fail Test is Enabled.

Use the procedures in Troubleshooting Problems When Adding a Trunk to isolate the problem.

If the problem persists after you perform the troubleshooting steps, contact Cisco Systems Technical Support:

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Updated: Oct 04, 2005Document ID: 17718