A Local Area Network (LAN) connects devices within a limited geographic area allowing sharing of files, printers and email. A LAN consists of computers, network interface cards, networking media and traffic control devices. Network interface cards connect devices to the network and have a unique MAC address. Repeaters, hubs, bridges, switches and routers are networking devices that help extend coverage and direct traffic in a LAN. Repeaters regenerate signals to extend cable length while hubs connect ports without directing traffic. Bridges separate a LAN into segments while switches make forwarding decisions based on MAC addresses to improve efficiency. Routers connect different network technologies and direct traffic at an IP address level.

1. LAN
Local Area Network

2. LAN
• LAN is stand for Local Area Network.
• LANs make it possible for businesses that use
computer technology to share efficiently such
items as files and printers, and to make
possible communications such as e-mail.

3. LAN
• LANs are designed to do the following:
- operate within a limited geographic area
- allow many users to access high-bandwidth media
- provide full-time connectivity to local services
- connect physically adjacent devices
• LANs consist of:
- Computers.
- Network interface cards (NIC)s
- Networking media.
- Network traffic control devices
- and peripheral devices.

4. LAN Devices
Standard Network Diagram Shapes

5. Network Interface Card Device (NIC)
• A network interface card (NIC card or NIC) is a
printed circuit board that fits into the
expansion slot on a computer’s motherboard
or peripheral device.
• It is also called a network adapter. On
laptop/notebook computers.
• Its function is to adapt the host device to the
network medium.

6. Network Interface Card Device (NIC)

7. Network Interface Card Device (NIC)
• NICs are considered unique devices because
each individual NIC in the world carries a
unique code, called a Media Access Control
(MAC) address.
• This address is used to control data
communication for the host on the network.

8. Repeaters
• One of the disadvantages of any cable type that is
used is there is a limit of segment length that the
signal runs through the cable without
disappearing.
• For example: we primarily use (CAT5 UTP) which
can support up to 100 meters without any
problem.
• If we need to extend our network beyond that
limit, we must add a device to our network. This
device is called a repeater.

9. Repeaters
• The purpose of a repeater is regenerate and
retime network signals at the bit level to allow
them to travel a longer distance on the media.
• Repeaters are single-port quot;inquot; and single-port
quot;outquot; devices.

10. Hub
• The purpose of a hub is to regenerate and retime
network signals . This is done at the bit level to a
large number of hosts (e.g. 4, 8, or even 24) using a
process known as concentration.
• Hub is also known as a multi-port repeater. The
difference is the number of cables that connect to the
device.
• The reasons for using hubs are to create a central
connection point for the wiring media, and increase
the reliability of the network by allowing any single
cable to fail without disrupting the entire network.

11. Hub
• The HUB is classified as active or passive.
• Most modern hubs are active, they take energy from a
power supply to regenerate network signals. Some
hubs are classified as passive devices because they
merely split the signal to multiple users, passive hubs
do not regenerate bits.
• So which one increase the length of the cable?

12. Bridge
• A bridge is a device that designed to connect two
LAN segments.
• The purpose of a bridge is to filter traffic on a
LAN, to keep local traffic local, yet allow
connectivity to other part (segment) of the LAN
for traffic that has been directed there.
• How does the bridge know which traffic is local
and which is not?

13. Bridge
• The answer is the same one that the postal
service uses when asked how it knows which mail
is local. It looks at the local address. Every
networking device has a unique MAC address on
the NIC.
• The bridge keeps track of which MAC addresses
are on each side of the bridge and makes its
decisions based on this MAC address list.

14. Switch
• A switch is a device just like a bridge is. In fact a switch
is called a multi-port bridge, just like a hub is called a
multi-port repeater.
• The difference between the hub and switch is that
switches make decisions based on MAC addresses and
hubs don't make decisions at all.
• Because of the decisions that switches make, they
make a LAN much more efficient. They do this by
quot;switchingquot; data only out the port to which the proper
host is connected. In contrast, a hub will send the data
out all of its ports so that all of the hosts have to see
and process (accept or reject) all of the data.

15. Switch

16. Router
• The router makes decisions based on groups
of network addresses (Classes)
• Routers can also connect different
technologies, such as Ethernet, Token-
ring, and FDDI (Fiber Distributed Data
Interface).
• However, because of their ability to route
packets of information, routers have become
the backbone of the Internet, and running the
IP protocol.

17. Router
• The purpose of a router is to examine incoming
packets, choose the best path for them through
the network, and then switch them to the proper
outgoing port.
• Routers are the most important traffic-regulating
devices on large networks. They enable virtually
any type of computer to communicate with any
other computer anywhere in the world!

18. Break