A network map is a diagram of a computer network. These maps are made to find bottlenecks in network systems or locations that need rerouting. The network map is one of the most basic tools in a network designer’s toolkit. The physical layout of the network and the information related to its usage give a wealth of information that would be difficult to obtain by other means.
People have made network maps since the earliest days of computer networking. In these days, the technology behind networking was in its infancy. It wasn’t uncommon for large networks to only have one or two individuals that fully understood their scope. These maps were used to help those less familiar with the systems find the information they needed for layout and repairs.
One of the biggest innovations in network mapping came later, with automatic monitoring tools. These tools gave hard numbers related to the use and latency of network connections. When that information was combined with a standard network map, designers could see the real effects of their changes. Small changes in the network’s design were found to have major impacts on the usage patterns of the network.
In the early days, most of these maps were made by hand. Later, automatic network monitoring programs came on the market. These programs would operate through entire network spaces, locating all the end points, terminals and junctions. This information would go back to the main program and could make a map of the system. These maps differed from a standard network map in that they showed interactivity between parts, but rarely a true blueprint-style map.
There are three basic methods of creating a network map beyond simply drawing one; simple network management protocol (SNMP), active probing and route analytics. SNMP is an industry standard protocol and was originally developed as a method of locating failing hardware. With this method, the mapping software uses links to hardware locations of which it is already aware. It then asks those hardware pieces about ones they know, eventually drawing out the entire network.
An active probing network map takes a more aggressive approach. It floods the network with a special kind of information packet. These packets talk to the system's hardware and report to the program. Based on the information they retrieve and how long it took to retrieve it, the program can make a basic hardware map.
Route analytics is the newest of the three forms and is the only one made explicitly for network mapping. These programs mimic some of the tendencies of a network router, often acting as a clone of an existing piece of hardware. They monitor the information going through the system, cataloging addresses and times. Eventually, they gain enough information to piece together a basic network map—the longer the program runs, the more accurate the map.