Network Troubleshooting Guide

This document, titled "NETWORK TROUBLESHOOTING GUIDE" (Order Number: EK-339AB-GD-002), is a comprehensive manual designed to assist users in diagnosing and resolving problems in DECnet Phase IV and TCP/IP networks, specifically those running on VMS and ULTRIX operating systems.

The guide covers:

1. Overview of Networks: Introduces fundamental data communications concepts, network components, various topologies (Star, Ring, Bus, Mesh, Tree), and provides detailed descriptions of DECnet (its architecture, routing mechanisms, and layers) and Internet/TCP/IP networks (addressing, naming, routing, and key protocols like IP, RIP, ICMP, TCP, UDP, ARP, and SNMP).
2. Network Troubleshooting Methodology: Presents a structured, step-by-step approach to problem-solving. This includes detecting and refining problem statements, gathering and analyzing information, classifying errors (hard, inconsistent, intermittent, transient) and their sources (user, hardware, software, configuration, interoperability), isolating the problem to specific network levels (node/host, LAN, WAN), applying solutions, verifying results, and documenting the process.
3. Network Management and Troubleshooting Tools: Provides an overview and usage instructions for a wide array of tools used in VMS and ULTRIX environments, such as arp, Authorize Utility, Breakout Boxes, DECelms, DECmcc Management Station, LAN Traffic Monitor, LAT Control Program, netstat, Network Control Program (NCP), NMCC/DECnet Monitor, NMCC/VAX ETHERnim, ping, Protocol Analyzers, syslog daemon, Terminal Server Manager Software, and traceroute, and uerf.
4. Resources for Troubleshooting: Details how to leverage various diagnostic resources including VMS and ULTRIX log files, routing path trace procedures (using NCP and netstat), different types of NCP loopback tests (node-level, circuit-level, disruptive, non-disruptive), TCP/IP reachability tests, and analyzing network counters.
5. Network Troubleshooting Procedures: Offers a significant section of detailed, step-by-step procedures for addressing common and specific network problems, organized alphabetically by symptom or problem description (e.g., "Aborted Service Request," "Connection Timed Out," "Host Is Unreachable," "Broadcast Storm," "Line Synchronization Lost").
6. Ethernet Configuration Guidelines: Includes an appendix detailing configuration best practices for various Ethernet setups.

The manual is intended for network managers and troubleshooters who have a foundational understanding of VMS or ULTRIX system management.