A network can be defined as the interconnection of autonomous computers linked together to facilitate communication while networking is the simple concept of connected computers.
Networks and networking have grown exponentially over the last 15years; they have evolved at light speed just to keep up with huge increases in basic critical user needs such as sharing data and printers, as well as more advanced demands such as video conferencing.
TYPES OF NETWORKS
LOCAL AREA NETWORK (LAN)
A LAN (Local Area Network) is a group of computers and network devices connected together, usually within the same building. A Local Area Network (LAN) is a high-speed communication system designed to link computers and other data processing devices together within a small geographical area, such as a workgroup, department, or building. Local Area Networks implement shared access technology. This means that all the devices attached to the LAN share a single communications medium, usually a coaxial, twisted pair or fibre optic cable.
METROPOLITAN AREA NETWORK (MAN)
Metropolitan area networks or MANs are large computer networks usually spanning a city or a town. They typically use wireless infrastructure or optical fibre connections to link their sites.
The IEEE 802-2001 standard describes a MAN as being: “A MAN is optimized for a larger geographical area than is a LAN, ranging from several blocks of buildings to entire cities. MANs can also depend on communications channels of moderate to high data rates. A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations. MANs might also be owned and operated as public utilities. They will often provide means for internetworking of local networks. Metropolitan area networks can span up to 50km.”
WIDE AREA NETWORK (WAN)
Wide Area Network (WAN) is a computer network that covers a broad area. A WAN in compares to a MAN, is not restricted to a geographical location, although it might be restricted to a geographical locations, it might also be confined within the bounds of a state or country. A WAN connects several LANs, and may be limited to an enterprise (a corporation or organization) or accessible to the public.
The technology is high speed and relatively expensive. The INTERNET is an example of a worldwide public WAN.
Routers are used to connect networks together and route packets of data from one network to another. Routers, by default break up a broadcast domain, which is the set of all devices on a network segment that hear all broadcasts sent on that segment.
Routers also break up collision domains. This is an Ethernet term used to describe a network scenario where one particular device sends a packet on a network segment, forcing every other device on that segment to pay attention to it. At the same time, a different device tries to transmit, leading to a collision, after which both devices must retransmit one at a time.
Routers run on the layer 3 of the OSI (Open System Interconnection) reference model.
Switches are used for network segmentation based on the MAC addresses. Switches look at the incoming frame’s hardware addresses before deciding to either forward the frame or drop it.
Switches break up collision domains but the hosts on the switch are still members of one big broadcast domain.
A hub is really a multiple port repeater. A repeater receives a digital signal and re-amplifies or regenerates that signal, and then forwards the digital signal out all active ports without looking at any data. An active hub does the same thing. This means all devices plugged into a hub are in the same collision domain as well as in the same broadcast domain, which means that devices share the same bandwidth. Hubs operate at the physical layer of the OSI model.