CONTENTS

  Title Page

  Copyright Page

  How to Use This Manual

  1      Preparations for Problem Solving

  1.1     Problem Solving Tools

  1.2     Information Required for Problem Solving
    1.2.1      Constructing an NSAP Address for the DEC WANrouter
      1.2.1.1      Procedures for Networks with Phase IV Nodes
      1.2.1.2      Procedures for Networks with Phase V Nodes
    1.2.2      Constructing a Tower Set

  2      Diagnosing Problems

  2.1     Problem Solving Procedure

  2.2     DEC WANrouter Unreachable
    2.2.1      DEC WANrouter Will Not Load
    2.2.2      DEC WANrouter Fails to Respond
      2.2.2.1      Procedures for a DEC WANrouter Running the Routing Vector Algorithm
      2.2.2.2      Procedures for a DEC WANrouter Running the Link State Routing Algorithm

  2.3     DEC WANrouter Reachable
    2.3.1      Nonbroadcast Circuits Fail
      2.3.1.1      Checking HDLC and DDCMP Circuits
      2.3.1.2      Checking X.25 Permanent Circuits
      2.3.1.3      Checking Dynamically Assigned X.25 Circuits
    2.3.2      Remote Node Is Unreachable

  2.4     X.25 Problems
    2.4.1      Incoming Calls Cannot Be Received
    2.4.2      Outgoing Calls Cannot Be Made
    2.4.3      Local DTE Fails
      2.4.3.1      DTE Restart Failure
      2.4.3.2      Link Set Up Failure
      2.4.3.3      Line Set Up Failure

  2.5     Internet Protocol (IP) Problems
    2.5.1      Generating ICMP Echo Requests
    2.5.2      Diagnosing IP Problems

  3      Loopback Testing

  3.1     Testing the Line

  3.2     Testing the Circuits
    3.2.1      Loopback on HDLC, DDCMP, and LAPB Data Link Circuits
    3.2.2      Loopback on CSMA/CD Circuits

  3.3     Testing the Logical Link Between Nodes
    3.3.1      Checking the Local Nodes
    3.3.2      Checking Remote Nodes

  A   Event Logging

  A.1     Checking that Events Are Logged

  A.2     Event Logging Problem Solving

  A.3     Event Messages
    Access Control Violation . . . Cable Fault
    Carrier Check Failure . . . Deleted Remote NSAP
    Diagnostic Packet Received . . . Excessive Collision
    Frame Check Error . . . IP Address Packet Error Discard
    IP Adjacency State Change . . . LAN Phase IV Designated Router Change
    Late Collision . . . Load Request Completed
    Load Request Failed . . . Own LSP Purged
    PDU Format Error . . . Rejected Adjacency
    Rejected IP Adjacency . . . Send Error Threshold Reached
    Sequence Number Skipped . . . Switched Virtual Circuit Failed
    Test Indication . . . Verification Reject

  B   Reporting a Problem to Digital

  B.1     Details of the Software

  B.2     Details of the Problem

  TABLES

  1-1        Network Configurations and NSAP Addressing

  3-1        STARTLOOP MODEM CONNECT LINE Modes

  3-2        LOOP MOP COUNT, LENGTH, and DATA Arguments

  3-3        LOOP MOP Arguments for Loopback Through Assistant Systems

  3-4        LOOP LOOPBACK APPLICATION Arguments