INTRODUCTION :
computer network is a group of computers that are interconnected by electronic circuits or wireless transmissions of various designs and technologies for the purpose of exchanging data or communicating information between them or their users. Networks may be classified according to a wide variety of characteristics.
A system connecting different devices such as PC , printers and disk drives in a network Typically , each device in a network serves a specific purpose for one or more individuals . A network is a set of devices connected by media links . The links connecting the devise are often called communication channels . The type of network is determined by size , its ownership , physical architecture and the distance it covers . Generally network is divided in three types depending on their physical size .
a. Local Area Network . ( LAN )
b. Wide Area Network . ( WAN )
c. Metropolitan Area Network ( MAN )
I will discuss a bout ( LAN ) and ( WAN ) .
ALOCAL AREA NETWORK ( LAN ) : ـ
A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport.
Larger LANs are characterized by their use of redundant links with switches using the spanning tree protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and to segregate traffic with VLANs. Larger LANS also contain a wide variety of network devices such as switches, firewalls, routers, load balancers, and sensors.
ARCNET, Token Ring and many other technologies have been used in the past, and G.hn may be used in the future, but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently in use.
* Attributes of LAN :
1- The LAN transmits data amongst user stations .
2- The LAN transmission capacity is more than 1 Mbps .
3- The LAN channel is typically privately owned by the organization using the facility .
4- The geographical coverage of LANs is limited to areas less than 5 square kilometers .
* LAN can provide users :
1- Flexibility .
2- Speed .
3- Reliability .
4- Adaptability . 2
5- Security .
6- Transparent interface .
7- Access to the other LAN and WAN .
8- Hardware and software sharing .
9- Centralized management .
10- Private ownership of the LAN .
Larger LANs are characterized by their use of redundant links with switches using the spanning tree protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and to segregate traffic with VLANs. Larger LANS also contain a wide variety of network devices such as switches, firewalls, routers, load balancers, and sensors.
ARCNET, Token Ring and many other technologies have been used in the past, and G.hn may be used in the future, but Ethernet over twisted pair cabling, and Wi-Fi are the two most common technologies currently in use.
* Attributes of LAN :
1- The LAN transmits data amongst user stations .
2- The LAN transmission capacity is more than 1 Mbps .
3- The LAN channel is typically privately owned by the organization using the facility .
4- The geographical coverage of LANs is limited to areas less than 5 square kilometers .
* LAN can provide users :
1- Flexibility .
2- Speed .
3- Reliability .
4- Adaptability . 2
5- Security .
6- Transparent interface .
7- Access to the other LAN and WAN .
8- Hardware and software sharing .
9- Centralized management .
10- Private ownership of the LAN .
- WIDE AREA NETWORKS ( WAN ) :
A wide area network (WAN) is a computer network that covers a broad area (i.e., any network whose communications links cross metropolitan, regional, or national boundaries.
WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.
Conclusion
WAN
LAN
NO
It covers large geographical area
It covers small area
1
WAN operates on the principle of point to point
LAN operates on the principle of broadcasting
2
Not used for time critical application
Used for time critical application
3
Transmission speed is low
Transmission speed is high
4
Design & maintenance is not easy
Easy to design & maintain
5
WAN is point to point in nature
LAN is broadcasting in nature
6
Transmission or communication medium is PSTN or satellite link
Transmission medium is co-axial or UTP cable
7
WAN suffer from propagation delay
LAN does not suffer form propagation delay
8
9
4
Reference :
1 - V. S. Bagad & I. A. hotre .January 2007 . computer networks Technical Publications Pune . India .
2 – ( 2010 ,
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