What is the difference between a LAN and a WAN ? What is Local Area Network (LAN) ?What is WAN?

What is the difference between a LAN and a WAN ?

1__Local Area Network:
What is Local Area Network ? 

• A local area network (LAN) is usually privately owned and connects some hosts in a single office , building, or campus.
• Depending on the needs of an organization,
• a LAN can be as simple as two PCs and a printer in someone’s home office, or it can extend throughout a company and include audio and video devices.

Each host in a LAN has :

•  an identifier
• an address
• that uniquely defines the host in the LAN.

NOTE:

• A packet sent by a host to another host carries both the source host’s and the destination host’s addresses.
• In the past, all hosts in a network were connected through a common cable :
• which meant that a packet sent from one host to another was received by all hosts.
• The intended recipient kept the packet; the others dropped the packet.
• Today, most LANs use a smart connecting switch, which is able to recognize the destination address of the packet and guide the packet to its destination without sending it to all other hosts.
• The switch alleviates the traffic in the LAN and allows more than one pair to communicate with each other at the same time if there is no common source and destination among them.
• When LANs were used in isolation they were designed to allow resources to be shared between the hosts.
• LANs today are connected to each other and to WANs to create communication at a wider level.

2__Wide Area Network :
What is Wide Area Network (WAN)?What is WAN?
A wide area network (WAN) is also an interconnection of devices capable of communication. 

What is the difference between a LAN and a WAN ?there are some differences between a LAN and a WAN :

• A LAN is normally limited in size.
•  spanning an office, a building, or a campus.
• A LAN interconnects hosts .
• A LAN is normally privately owned by the organization that uses it.

• a WAN has a wider geographical span, spanning a town, a state, a country, or even the world.
• a WAN interconnects connecting devices such as switches, routers, or modems.
• a WAN is normally created and run by communication companies and leased by an organization that uses it.

We see two distinct examples of WANs today:
 point-to-point WANs and switched WANs.

Types of network WAN :
1__Point-to-Point WAN :
What is Point-to-Point WAN ?
A point-to-point WAN is a network that connects two communicating devices through a transmission media (cable or air). 
an example of a point-to-point WAN :

 

2__Switched WAN 
What is Switched WAN ?

• A switched WAN is a network with more than two ends.
• used in the backbone of global communication today.
• We can say that a switched WAN is a combination of several point-to-point WANs that are connected by switches.

an example of a switched WAN :

Internetwork

What is Internetwork? 
Today, it is very rare to see a LAN or a WAN in isolation; they are connected to one another.
 When two or more networks are connected, they make an internetwork, or internet. 
NOTE:
As an example, assume that an organization has two offices, one on the east coast and the other on the west coast.
 Each office has a LAN that allows all employees in the office to communicate with each other.
To make the communication between employees at different offices possible, the management leases a point-to-point dedicated WAN from a service provider, such as a telephone company, and connects the two LANs.
Now the company has an internetwork, or a private internet (with lowercase i).
Communication between offices is now possible.