This document is intended to help people who are planning to set up a new network based on the Internet protocols, or to administer an existing one. It assumes a basic familiarity with the TCP/IP protocols, particularly the structure of Internet addresses. A companion paper, Introduction to the Internet Protocols, may provide a convenient introduction. This document does not attempt to replace technical documentation for your specific TCP/IP implementation. Rather, it attempts to give overall background that is not specific to any particular implementation. It is directed specifically at networks of "medium" complexity. That is, it is probably appropriate for a network involving several dozen buildings. Those planning to manage larger networks will need more preparation than you can get by reading this document.

In a number of cases, commands and output from Berkeley Unix are shown. Most computer systems have commands that are similar in function to these. It seemed more useful to give some actual examples that to limit myself to general talk, even if the actual output you see is slightly different.

Table of Contents

1. The problem

1.1 Some comments about terminology
2. Routing and Addressing
3. Choosing an addressing structure
3.1 Should you subdivide your address space?
3.2 Subnets vs. multiple network numbers
3.3 How to allocate subnet or network numbers
3.4 Dealing with multiple "virtual" subnets on one network
3.4.1 Dealing with Multiple Subnets by Turning off Subnetting
3.4.2 Multiple Subnets: Implications for Broadcasting
3.5 Choosing an address class
3.6 Dialup IP and Micro gateways: Dynamically assigned addresses
3.6.1 Dialup IP
3.6.2 Micro gateways
4. Network-wide Services, Naming
5. Setting up routing for an individual computer
5.1 How datagrams are routed
5.2 Fixed routes
5.3 Routing redirects
5.4 Other ways for hosts to find routes
5.4.1 Spying on Routing
5.4.2 Proxy ARP
5.4.3 Moving to New Routes After Failures
6. Bridges and Gateways
6.1 Alternative Designs
6.1.1 A mesh of point to point lines
6.1.2 Circuit switching technology
6.1.3 Single-level networks
6.1.4 Mixed designs
6.2 An introduction to alternative switching technologies
6.2.1 Repeaters
6.2.2 Bridges and gateways
6.2.3 More about bridges
6.2.4 More about gateways
6.3 Comparing the switching technologies
6.3.1 Isolation
6.3.2 Performance
6.3.3 Routing
6.3.4 Network management
6.3.5 A final evaluation
7. Configuring Gateways
7.1 Configuring routing for gateways

Copyright © 1988 Charles L. Hedrick, Rutger's University

HTML version: Ian Harries <ih@doc.ic.ac.uk>