Network Resources

Advantages and Disadvantages of different topologies

LAN

LAN

A local area network (LAN) consists of two or more computers connected together in a building or home using software and hardware. This is contrasted to a wide area network (WAN) such as the Internet, which covers a large geographic area. In a LAN, there is a main computer or server, and remote computers called clients. By creating this type of network in the home or office, computers on it can share files, resources, and if desired, an Internet connection.

A LAN can be one of two types: wired or wireless. A wired LAN requires Ethernet cable to physically connect all computers on the network to a main device called a switch. The wireless type uses radio waves to communicate, eliminating the need for wires. Therefore, the hardware used in the network should all be of either the wireless or wired type.


Use of LAN
Followings are the major areas where LAN is normally used
•File transfers and Access
•Word and text processing
•Electronic message handling
•Remote database access
•Personal computing
•Digital voice transmission and storage

WAN

A Wide Area Network (WAN) is a network that spans a large geographical area, the most common example being the Internet. This is contrasted to smaller local area networks (LANs)and metropolitan area networks (MANs). LANs are home or office networks, while a MAN might encompass a campus or service residents of a city, such as in a citywide wireless or WiFi network.

The Internet is a public WAN, but there are many ways to create a business model or private version. A private network is essentially two or more LANs connected to each other. For example, a company with offices in Los Angeles, Texas and New York might have a LAN setup at each office. Through leased telephone lines, all three LANs can communicate with each other, forming a WAN.

Routers are used to direct communications between LANs communicating on a WAN. The router, installed on the leased line, reads the "envelopes" or headers on each packet of data that passes through the WAN, sending it to the proper LAN. When the packet arrives at the LAN, a device called a switch sends the data packet on to the correct machine. Hence, the WAN acts like an interface between LANs for long-distance communication. One that runs on a leased line is private, as there is no public traffic on the line.

TOPOLOGIES

Bus

A bus network uses a multi-drop transmission medium, all node on the network share a common bus and thus share communication. This allows only one device to transmit at a time. A distributed access protocol determines which station is to transmit. Data frames contain source and destination addresses, where each station monitors the bus and copies frames addressed to itself.


A bus topology connects each computer (nodes) to a single segment trunk (a communication line, typically coax cable), that is referred to as the 'bus'. The signal travels from one end of the bus to the other. A terminator is required at each to absorb the signal so as it does not reflect back across the bus. A media access method called CSMA/MA is used to handle the collision that occur when two signals placed on the wire at the same time. The bus topology is passive. In other words, the computers on the bus simply 'listen' for a signal; they are not responsible for moving the signal along.

Advantages and Disadvantages of the bus topology

Advantages:

Failure of one of the station does not affect others.

Good compromise over the other two topologies as it allows relatively high rate of data tansmittion.

Well suited for temporary networks that must be set up in a hurry.

Easy to implement and extend.


Disadvantage:

Require a network to detect when two nodes are transmitting at the same time.

Does not cope well with heavy traffic rates

Difficult to administer/troubleshoot.

Limited cable length and number of stations.

A cable brake can disable the entire network; no redundancy.

Maintenance cost may be higher in the long run.

Performance degrade as additional computers are added.

Ring

—In a ring network each device (workstation, server, printer) is connected to two other devices, this forms a ring for the signals to travel around. Each packet of data on the network travels in one direction and each device receives each packet in turn until the destination device receives it.

Advantages and Disadvantages of ring topology

Advantages:

This type of network can transfer data quickly, even if there are a large number of devices connected because the data only flows in one direction, so there won’t be any data collisions.

If the main cable fails or any device is faulty then the whole network will fail.


Disadvantages:

If the main cable fails or any device is faulty then the whole network will fail.

Star

— In a star network each device on the network has its own cable that connects to a switch or hub. A hub sends every packet of data to every device, whereas a switch only sends a packet of data to the destination device.

Advantages and Disadvantages of Star topology

Advantages:

Very reliable – If one cable or device fails then all the others will continue to work

High performing as no data collisions can occur


Disadvantages:

Expensive to install as this type of network uses the most cable (network cable is expensive)

Extra hardware required (hubs or switches) which adds to cost

If a hub or switch fails all the devices connected to it will have no network connection


Whar are the components required to put together a network?

Server

A computer or computer program that manages access to a centralized resource or service in a network.


A server can vary at a range of prices, some are for £200 and others are for £2000.


Work space (i.e computer)

Where your computer, keyboard and monitor is.

Ethernet Cables

Ethernet cables connect network devices such as modems, routers, and adapters. They transmit data using the Ethernet protocol.

Printer

A machine for printing text or pictures onto paper, esp. one linked to a computer.