Easy to learn this topic..............

1. LAN
(Local Area Network)

2. Content
• Network introduction
• LAN
• Types of LAN
• LAN topology
• Advantage
• Disadvantage

3. What is a Computer Network?
 Collection of autonomous computers
interconnected by a single technology is called
computer network.
 Two computers are set to be interconnected if
they are able to exchange information.
• Connection can be through a copper wire, fiber
optics, microwaves, infrared or satellite.

4. CATEGORIS
OF
NETWORKS

5. LAN
A local area network (LAN) is usually
privately owned and links the devices in a
single office, building ,or campus .
It can extend throughout a company and
include voice, sound, and video peripherals.
LAN size is limited to a few kilometers.
Most common LAN topologies are bus, ring ,
and star.

6. LAN

7. Types of LAN
The three most popular types of LANs
are:
•Token ring network
•FDDI (Fiber Distributed Data Interface)
network
•Ethernet

8. Token ring network
Originally developed by IBM in 1970’s
Still IBM’s primary LAN technology
In cases of heavy traffic, the token ring
network has higher throughput than
ethernet due to the deterministic (non-
random) nature of the medium access

9. Is used in applications in which delay
when sending data must be
predictable
Is a robust network i.e. it is fault
tolerant through fault management
mechanisms
Can support data rates of around 16
Mbps
Typically uses twisted pair

10. FDDI (Fiber Distributed
Data Interface)
FDDI is a standard developed by the
American National Standards Institute
(ANSI) for transmitting data on optical
fibers
Supports transmission rates of up to
200 Mbps

11. Uses a dual ring
First ring used to carry data at 100
Mbps
Second ring used for primary
backup in case first ring fails
If no backup is needed, second ring
can also carry data, increasing the
data rate up to 200 Mbps
Supports up to 1000 nodes
Has a range of up to 200 km

12. First network to provide CSMA/CD
Developed in 1976 by Xerox PARC
(Palo Alto Research Center) in
cooperation with DEC and Intel
Is a fast and reliable network solution
Ethernet

13. One of the most widely implemented
LAN standards
Can support data rates in the range of
10Mbps- 10 Gbps
Used with a bus or star topology

14. There are three topologies of LAN Network
Bus
Topology
Star
Topology
LAN
Topologi
es
Ring
Topology

16. Bus Topology
• Stations attach to linear
medium (bus)
– Via a tap - allows for
transmission and reception
• Transmission propagates in
medium in both directions
• Received by all other stations
– Not addressed stations ignore
• Need to identify target station
– Each station has unique
address
– Destination address included in
frame header
• Terminator absorbs frames at
the end of medium 16

17. Bus Topology
• Need to regulate transmission
– To avoid collisions
• If two stations attempt to transmit at same
time, signals will overlap and become garbage
– To avoid continuous transmission from a single
station. If one station transmits continuously,
access is blocked for others
• Solution: Transmit Data in small blocks –
frames
ALTTC LAN & VLAN 17

18. Ring Topology
• Repeaters joined by point-to-point links in
closed loop
– Links are unidirectional
– Receive data on one link and retransmit on
another
– Stations attach to repeaters
• Data transmitted in frames
– Frame passes all stations in a circular manner
– Destination recognizes address and copies
frame
– Frame circulates back to source where it is
removed
18

19. Ring Topology
ALTTC LAN & VLAN 19

20. Star Topology
• Each station connected
directly to central node
– using a full-duplex
(bi-directional) link
• Central node can broadcast (hub)
– Physical star, but logically like bus
due to broadcast medium
– Only one station can transmit at a
time; otherwise, collision occurs
• Central node can act as frame switch
– retransmits only to destination
– today’s technology
20

21. A work to internet connections would most likely
require broadcast network (LAN) with a connection
to the internet (packet switched network)

22. Expensive hardware can be
shared e.g. laser printer.
Users can access the same
files.
Messages can be sent between
users.
A single Internet connection can
be shared among many users.
Network software is cheaper
than buying individual
packages.
Advantage of LAN

23. Disadvantage of LAN
• Special security measures
are needed to stop users from
using programs and data that
they should not have access
to;
• Networks are difficult to set
up and need to be maintained
by skilled technicians.