Monday, December 12, 2011

Network Components and Topolgies


What Is a Network?
A network is a connected collection of devices and end systems, such as computers and servers, which can communicate with each other. Networks carry data in many types of environments, including homes, small businesses, and large enterprises.

Common Physical Components of a Network
These are the four major categories of physical components in a computer network:
Personal computers (PCs): The computers serve as end points in the network, sending and receiving data.
Interconnections:  a means for data to travel from one point to another. Interconnections include:
— Network interface cards (NICs) that translate the data produced by the computer into network
— Network media, such as cables or wireless media.
— Connectors that provide the connection points for the media
Switches: Switches are devices that provide network attachment to the end systems and switching of the data within the local network.
Routers: Routers interconnect networks and choose the best paths between networks


Physical Topologies
The physical topology of a network refers to the physical layout of the devices and cabling. Here are the three primary categories of physical topologies:

Bus: computers and other network devices were cabled together in a line using coaxial cable.


Ring: Computers and other network devices are cabled together, with the last device connected to the first to form a circle, or ring. The physical connection can be made using either coaxial or fiber.


Star: A central cabling device connects the computers and other network devices. This category includes both star and extended-star topologies. The physical connection is commonly made using twisted-pair wiring.


Extended Star

full-mesh: topology connects all devices (or nodes) to one another for redundancy and fault tolerance. Implementing a full-mesh topology is expensive and difficult. This method is the most resistant to failures, because any single link failing will not affect reach ability.


partial-mesh: topology, at least one device maintains multiple connections to all other devices, without being fully meshed. 



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