Computer Network

Computer Network Topologies

Network design plays an integral part in operation and performance. A network consists of multiple computers connected using some type of interface, each having one or more interface devices such as a Network Interface Card (NIC) and/or a serial device for PPP networking. Each computer is supported by network software that provides the server or client functionality. The hardware used to transmit data across the network is called the media. A network's topology dictates the media to be used, the type of channel access, and the speed at which the network operates. It not only refers to the physical layout of its computers, cables and resources, but also how those components communicate with each other. Cable arrangement in a network is considered to be physical topology whereas the path between computers that data travels is logical topology.

According to an internet article on www.about.com, "network topologies are categorized into the following basic types: Bus, ring, star, tree and mesh" (Bradley, 2008). This article also stated, "Bus networks (not to be confused with the system bus of a computer) use a common backbone to connect all devices. With a single cable, the backbone functions as a shared communication medium that devices attach or tap into with an interface connector.

In a ring network, every device has exactly two neighbors for communication purposes. All messages travel through a ring in the same direction (either "clockwise" or "counterclockwise"). A failure in any cable or device breaks the loop and can take down the entire network.

A star network features a central connection point called a "hub" that may be a hub, switch or router. Devices typically connect to the hub with Unshielded Twisted Pair (UTP) Ethernet. A star network generally requires more cable, but a failure in any star network cable will only take down one computer's network access and not the entire LAN.

Tree topologies integrate multiple star topologies together onto a bus. In its simplest form, only hub devices connect directly to the tree bus, and each hub functions as the "root" of a tree of devices.

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination" (Bradley, 2008). Mesh networks ideally allow each computer to have a direct connection to each of the other computers.

Research has shown that networks fall into two major types: peer-to-peer and client-server.

In a server based network, there are computers set up to be primary providers of services such as

file service or mail service. The computers providing the service are are called servers and the

computers that request and use the service are called client computers.

In a peer-to-peer network, every user must act as a network administrator, controlling access to the resources on their machines. Users can also give unlimited access to resources or grant restricted access to other users on the network. Likewise, users can decide whether other users can access resources simply by requesting them or whether they must supply a password for access