Types of Networks

Types of Networks

By using local-area network (LAN) and wide-area network (WAN) technologies, many computers are interconnected to provide services to their users.
In providing services, networked computers take on different roles or functions in relation to each other.
Some types of applications require computers to function as equal partners. Other types of applications distribute work so that one computer functions to serve a number of others in an unequal relationship.

Peer-to-Peer Networks



In a peer-to-peer network, the networked computers act as equal partners, or peers, to each other.

As peers, each computer can take on the client function or the server function alternately.






Client/Server Networks

In a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients.

The server contains the file, print, application, security, and other services in a central computer that is continuously available to respond to client requests.





Local-Area Network (LAN)





A local-area network (LAN) can connect many computers in a relatively small geographical area such as a home, an office, or a campus.

It allows users to access high bandwidth media like the Internet and allows users to share devices such as printers.

Toplogy

•The general shape or layout of a LAN is called its topology.
•Topology defines the structure of the network. This includes the physical topology which is the actual layout of the wire or media, and the logical topology which is how the media is accessed by the hosts

•The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.

Bus topology

All nodes are connected to a central cable along which data is passed. called Bus Topology.

Ring topology

each computer is connected to the network in a closed loop or ring. Each machine or computer has a unique address that is used for identification purposes.
•A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame.
•The frame then continues around the ring until it finds the destination node, which takes the data out of the frame.





–Single ring – All the devices on the network share a single cable
–Dual ring – The dual ring topology allows data to be sent in both directions although only one ring is used at a time.

Star topology

ach machine is connected to a central hub. In contrast to the bus topology, the star topology allows each machine on the network to have a point to point connection to the central hub. All of the traffic which transverses the network passes through the central hub.

•The star topology is the most commonly used architecture in Ethernet LANs.
•When installed, the star topology resembles spokes in a bicycle wheel.



Larger networks use the extended star topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.

Mesh topology

A type of network setup where each of the computers and network devices are interconnected with one another, allowing for most transmissions to be distributed, even if one of the connections go down.

Wide-Area Networks (WAN)

• A WAN, as the name implies, is designed to work over a larger area than a LAN. •A WAN uses point-to-point or point to multipoint, serial communications lines.

•Point-to-point lines connect only two locations, one on each side of the line. Point-to-multipoint lines connect one location on one side of the line to multiple locations on the other side.

•The following are some of the more common WAN technologies:
–Modems
–Integrated Services Digital Network (ISDN)
–Digital subscriber line (DSL)
–Frame Relay
–Asynchronous Transfer Mode (ATM)

•Connections across WAN lines may be temporary or permanent.
•Telephone or dialup lines, might make a temporary connection to a remote network from a computer in a home or small office.
•In both temporary and permanent cases, computers that connect over wide area circuits must use a modem or channel service unit/data service unit (CSU/DSU) at each end of the connection.