A wide area network (WAN) connects multiple local area networks (LANs) over a large geographical area like a country or continent. The hosts on the LANs are connected through communication lines and routers that make up the WAN subnet. The subnet carries messages between hosts, allowing computers in different locations to communicate. The objectives of building a WAN include consolidating data, voice and video services, reducing network costs, and improving performance through optimization. However, WANs are difficult for businesses to manage as traffic increases with cloud computing and emerging technologies. Cost effectiveness and reliability can also be challenges with WAN upgrades.

1. WIDE AREA NETWORK (WAN)

2. Introduction
A wide area network or WAN, spans a
large geographical area, often a
country or continent. WAN (Wide Area
Network) connects two or more LANs
and other networks so
that computers at one location can
communicate to the computers at far
away some other location. It contains a
collection of machines intended for
running user (i.e. application)
programs. We call these machines as
hosts.

3. The hosts are connected by
communication subnet or just subnet for
short. The host are owned by costumers
(e.g. people’s personal
computers), whereas the communication
subnet is typically owned and operated by
a telephone company or Internet service
provider. The job of subnet is to carry
message from host to host, just as
telephone system carries words from
speaker to listener.
In most wide area networks, the subnet
consists of two distinct components:
transmission lines and switching elements.
Transmission lines move bits between
machines.

4. They can be made of copper
wire, optical fiber, or even radio links.
Switching elements are specialized
computers that connect three or more
transmission lines. When data arrive on
an incoming line, the switching element
must choose an outgoing line on which
to forward them. Nowadays router is
most commonly used as switching
element.

5. Host Subnet
Router
LAN
Fig:Relation between hosts on LANs and the subnet.

6. (Subnet means the collection of routers
and communication lines that moved
packets from the source host to the
destination host.)
In this model, shown in fig, each host is
frequently connected to a LAN on which
a router is present, although in some
cases a host can be connected directly
to a router. The collections of
communication lines and routers (but not
from the hosts) form the subnet.

7. Subnet
Router Receiving host
Sending host
B D
E
A
C
Sending process Packet Receiving process
Router C makes a choice to forward
Packets to E and not D
Fig: A stream of packets from sender to receiver.

8. OBJECTIVES
1.To build a uniform multiservice network
for data, voice, and video consolidation.
2.To reduce recurring network operation
costs (such as bandwidth).
3.To reduce management costs and
focus on core competencies.
4.Performance can be improved by
optimization of WAN.

9. Scope
Integrated services in digital networks
Network managements
Multimedia communications
Wireless WAN
Developer

10. Limitation
WAN is difficult for businesses as cloud
computing and other emerging
technologies converge upon the network.
Cost effectiveness is a major problem when
it comes to WAN upgrades, in large
part, because the network format is not
built for such large amounts of traffic.
Harder to manage since the solution
typically involves multiple vendors &
reliability of solution goes down