CONTENTS

  Title Page

  Copyright Page

  Preface

  1      Introduction to DECdts

  1.1     DECdts Advantages
    1.1.1      Applications Support
    1.1.2      External Time-Provider Support
    1.1.3      Manageability
    1.1.4      Quantitative Inaccuracy Measurement

  1.2     Basic DECdts Concepts
    1.2.1      Time Measurement Factors
      1.2.1.1      Clock Error
      1.2.1.2      Communications and Processing Uncertainties
    1.2.2      Inaccuracy
    1.2.3      Synchronizing System Clocks
    1.2.4      How DECdts Adjusts System Clocks
    1.2.5      DECdts Time Representation
      1.2.5.1      Absolute Time
      1.2.5.2      Relative Time

  1.3     How DECdts Works
    1.3.1      Clerks
    1.3.2      Servers
      1.3.2.1      Local Servers
      1.3.2.2      Global Servers
      1.3.2.3      Couriers

  1.4     Interoperation with DNS

  2      Managing DECdts

  2.1     The DECdts Management Interface
    2.1.1      Accessing and Exiting the Management Interface
    2.1.2      Command Syntax
    2.1.3      DECdts Timestamp Syntax
    2.1.4      Enabling DECdts
    2.1.5      Designating Global Servers and Couriers
      2.1.5.1      Advertising Global Servers to DNS
      2.1.5.2      Designating Global Servers with the Site-Specific Template
      2.1.5.3      Assigning the Courier Role to Servers

  2.2     Summary of DECdts Commands and Characteristics

  2.3     Routine Management Tasks
    2.3.1      Critical Commands and Characteristics
      2.3.1.1      The Servers Required Characteristic
      2.3.1.2      The Maximum Inaccuracy Characteristic
      2.3.1.3      The Synchronization Hold Down Characteristic
      2.3.1.4      The Error Tolerance Characteristic
      2.3.1.5      The LAN Timeout, WAN Timeout, and Query Attempts Characteristics
    2.3.2      Server Management
      2.3.2.1      Matching the Epoch
      2.3.2.2      The Advertisement Interval and Check Interval Characteristics
    2.3.3      Modifying the System Time
      2.3.3.1      Updating the Time Monotonically
      2.3.3.2      Changing System Time Nonmonotonically
      2.3.3.3      Forcing System Synchronization
      2.3.3.4      Setting the System Clock to Local Time

  3      Problem Solving

  3.1     A Clerk System's Clock is Incorrect

  3.2     A Server System's Clock is Incorrect
    3.2.1      Large Inaccuracy On One Server
    3.2.2      Large Inaccuracy On All Servers

  3.3     A Clerk or Server Cannot Find Local Servers

  3.4     A Clerk or Server Cannot Find Global Servers

  3.5     The Advertise Command Fails
    3.5.1      Incorrect Global Server Directory
    3.5.2      Global Directory Not Configured
    3.5.3      Access Violation Messages

  4      DECdts Command Dictionary

  introduction

  advertise

  change

  delete

  disable

  enable

  set

  show

  synchronize

  update

  A   DTSS System and OPCOM Messages

  A.1     DTSS System Messages

  B   Time-Providers and Time Services

  B.1     Criteria for Selecting a Time Source

  B.2     Sources of Coordinated Universal Time
    B.2.1      Telephone Services
    B.2.2      Radio Transmissions
    B.2.3      Satellite

  B.3     World Time Zone Map

  C   Event Messages

  Glossary

  FIGURES

  1-1        Time and Inaccuracy

  1-2        Computed Time

  1-3        Adjustment of the Clock

  1-4        Time Display Format

  1-5        Time Display Format Variants

  1-6        DECdts Operation

  2-1        Local Fault

  B-1        World Time Zone Map

  TABLES

  1-1        Time-Provider Programs and Related Time-Provider Suppliers

  2-1        DECdts Commands

  2-2        Settable DECdts Characteristics

  B-1        Time-Provider Selection Criteria