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 A+ Essentials (220-801) Cram Notes

   

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2.8 Identify various types of networks

LAN (Local Area Network):A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet. In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring.

WAN (Wide Area Network) : As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the Earth. A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a WAN. In IP networking, the router maintains both a LAN address and a WAN address. A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.

PAN (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 appointments, digital photos and music. Personal area networks can be constructed with cables or be wireless. USB and FireWire technologies often link together a wired PAN, while wireless PANs typically use Bluetooth or sometimes infrared connections. Bluetooth PANs are also sometimes called piconets. Personal area networks generally cover a range of less than 10 meters (about 30 feet). PANs can be viewed as a special type (or subset) of local area network (LAN) that supports one person instead of a group.

MAN (Metropolitan Area Network):is a network that interconnects users with computer resources in a geographic area or region larger than that covered by even a large local area network (LAN) but smaller than the area covered by a wide area network (WAN). The term is applied to the interconnection of networks in a city into a single larger network (which may then also offer efficient connection to a wide area network). It is also used to mean the interconnection of several local area networks by bridging them with backbone lines. The latter usage is also sometimes referred to as a campus network.

   Topologies:

A topology is physical and logical network layout. Physical layout include actual layout of cables and other network devices where as Logical layout include the way in which the network appears to the devices that use it.

Mesh : In this topology each computer is connected to every other. This topology is rarely used.

Advantages:

            - It provide multiple paths between two devices so if one path fails other can be used.

            - Network can be expanded without distruption to current uses

Disadvantages

            - It has high level of redundancy

            - wiring is very complicated

            - Cabling cost is very high

            - Finding fault in cabling is very tricky

           

Ring :In this topology each network computer and device are connected to each other forming a large circle (or similar shape). Each packet is sent around the ring until it reaches its final destination. Typically FDDI, SONET or Token Ring technology are used to implement a ring network.

Advantages:

            - Any fault in cable can be found easily.

            - These networks are comparatively easy to install.

Disadvantages:

            - Expansion will cause disruption in current network

            - Single fault in cable will disrupt entire network.

 

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