Network Topologies

The word Topology comes from the greek word topos meaning place and logos meaning

study. It is a description of any locality in terms of its layout. Topology is a branch of

mathematics concerned with properties of geometric figures that are distorted without tearing

or bonding together.

A network topology is the pattern in which nodes are connected to a local area network

or another network via links such as cables.

There are four principal topologies used in local area networks. There are bus, ring, star,

and mesh. The most widely used of these is bus, because Ethernet employs it, which is the

dominant local area network architecture. In a bus topology, all devices are connected to a

central cable called the backbone. This topology is relatively inexpensive and easy to install for

small networks.

In a ring topology, each device is connected directly to two other devices, one on either

side of it to form a closed loop. This topology is relatively expensive and difficult to install, but it

offers high bandwidth and can span large distances. A variation is the token ring, in which

signals travel in one direction around the loop carried by a token from node to node.

In a star topology, all devices are connected directly to a central computer or server.

Such networks are relatively easy to install and manage, but bottlenecks can occur because all

data must past through the central device.

The mesh topology can be either a full mesh or a partial mesh. In the former, each

computer is connected directly to each of the others. In the latter, some computers are

connected to most of the others, and some connected only to those other nodes with which

they exchange the most data.

The several basic networks topologies can be combined in various ways to form hybrid

topologies, such as ring-star network or a tree network. The latter consists of two or more star

networks connected to a linear bus.

The word Topology comes from the greek word topos meaning place and logos meaning

study. It is a description of any locality in terms of its layout. Topology is a branch of

mathematics concerned with properties of geometric figures that are distorted without tearing

or bonding together.

Wide Are Network

A wide area network is a network that covers a broad area using leased

telecommunication lines. An example of a wide area network is any telecommunications

network that links across metropolitan, regional, national or international. Business and

government entitles utilize wide area networks to relay data among employees, clients, buyers,

and suppliers from various geographical locations. In essence, this mode of telecommunication

allows a business to effectively carry out its daily functions regardless of the location. The

Internet can also be considered as a wide area network, and is used by business, governments,

organizations, and individuals for almost any purpose imaginable.

Communication Service Provider

A communication service provider is a service provider that transports information

electronically. An example would be telecommunications service provider. The term

encompasses public and private companies in the telecom, Internet, cable, and satellite.

The market in which a communication service provider specializes is often a function of

the industry served. These industries can be divided into three categories: telecommunications,

entertainment and media, and Internet services. Some communication service providers have

branched into multiple areas. Others provide communication services across all major

categories.

The term CSP came into vogue in the late 1990s. Prior to this time, communications

businesses were highly specialized, with little overlap between traditional telecom, cellular,

cable, and Internet companies. In the 1990s, deregulation and technology convergence began

to cause massive upheaval in the industry. As companies began to offer broader portfolios of

communications services, traditional categories were inadequate to describe service providers.

The term "communications service provider" is now widely accepted as a broad category

encompassing all of these businesses.

WAN – Hardware

A wide area network is a network with a much broader reach than local area networks

and metropolitan area networks. They span across metropolitan areas and may well span

across nations and language differences. The PSTN- Public Switched Telephone Network or

POTS- Plain Old Telephone System is a wide area network. The entire Internet is a wide area

network. A home user’s connection to the Internet is very likely done through a wide area

network. While they interact with local area networks, they are fundamentally different in form

and functions.

The hardware required to implement a wide area network link can be as simple and

readily available as a modem and a telephone line. On the other hand, it can be complicated

and expensive, such as satellites and transoceanic cabling. There are different types of wide

area network hardware, such as modems, external modems, ISDL and DSL adapters, and CPE.

Controller Area Network

Controller area network is a serial network that was originally designed for the

automotive industry, but has also become a popular bus in industrial automation as well as

other applications. The CAN bus is primarily used in embedded systems, and as its name

implies, is the network established among microcontrollers. It is a two-wire, half duplex, high-

speed network system and is well suited for high speed applications using short messages. Its

robustness, reliability and the large following from the semiconductor industry are some of the

benefits with CAN.

Personal Area Network

A personal area network is a computer network organized around an individual person.

Personal area networks typically involve a mobile computer, a cell phone and or a handheld

computing device such as a PDA. You can use these networks to transfer files including email

and calendar schedules and appointments, photos, videos and music.

Personal area networks can be constructed with cables or be wireless. USB and firewire

technologies often link together a wired personal area network, while wireless personal area

networks typically use Bluetooth or infrared connections. Bluetooth personal area networks are

also called piconets.

Personal area networks generally cover a range of less than 10 meters. Personal area

networks can be viewed as a special type of local area network that supports only one person

instead of a group.

SOURCES:

http://www.linfo.org/network_topology.html

http://www.pcmag.com/encyclopedia/term/54193/wan

http://zaielacademic.net/networking/wan_hardware.htm

http://hem.bredband.net/stafni/developer/CAN.htm

http://compnetworking.about.com/od/networkdesign/g/bldef_pan.htm