Staffsite STMIK PPKIA Pradnya Paramita 0b22b modul 01

Module 1:
Understanding Local
1.2 Understand local area networks (LANs)
1.5
Understand
network topologies and access
Area
Networks
methods

Agenda
1

Local Area Networks

2

Data Transfer on a LAN

3


Types of Local Area Network

Local Area
Networks

What is a network?
A network is two devices connected to each other with a
physical medium, such as wires or radio signals
• The connection allows those two devices to exchange data


What is the purpose of networks?
Networks enhance many aspects of life and business for
individuals and organizations, including:
• communication and collaboration
• sharing information and resources
• organizing data
• saving costs

How are networks organized?

Networks are organized
based on their geographic
location
• A Local Area Network, or
LAN, is a group of computers
or devices that:


• are confined to a small geographic area,

such as a single building
• share a common communication
medium, such as cabled or wireless
connections
• are connected to a central connecting
device, like a hub, switch, or router

Network Documentation
Describes, defines, and
explains the physical and

logical method for
connecting devices
• The documentation phase
occurs before a network is
built, or when changes are
made to the network
• Microsoft Visio is a tool that
can be used to document
networks


What devices make up LANs?
CENTRAL
CONNECTING
DEVICES

HOSTS

Desktop
PCs


Laptops

Phones
Switch

Hub

Router
Servers

Tablets

What are hosts?
Desktop PCs, laptops, cell phones, servers, routers and so on
• A host can be any device that has an IP address – an address
used to send and receive data in a network


• IP addresses help identify devices and the networks where they are located


What are central connecting devices?
Hubs, switches, and routers act as central connecting devices
• Central connecting devices are responsible for:


• connecting hosts
• transmitting data



Different central connecting devices perform these functions in
different ways

How do hubs function?
Hosts send data to a hub
• The hub then broadcasts that
data to all other connected
hosts on the network



How do switches function?
Hosts send data to a switch
• Switches direct data to its
intended destination
• Unlike hubs, switches can
send and receive data
simultaneously
• Switches are the most
common device used to
connect hosts to a network


How do routers function?


Routers are at the edge of
LANs
• They act as a gateway to other


networks



Routers allow communication
between hosts on different
networks

Internet
24.136.72.110
192.168.1.1

What are central connecting devices?
• Computers have network adapters, also

known as Network Interface Cards (NICs),
that allow them to connect to networks
• NICs via wires or wireless signals
• Wired adapters feature an RJ45 port
• Wireless adapters feature an antenna and connect to


networks using Wireless Access Points (WAPs)

Ethernet Cables
Ethernet cables are made of
copper wires
• Transmit data in the form of
electrical pulses


• Wireless connections rely on different

technologies

RJ45
PLUG

Ethernet Cables
WAPs provide a central point of
access for devices that want to

connect to a Local Area Network
(LAN)
• Wireless networks can consist of
many types of devices other than
traditional PCs:


• Smart phones
• PDAs
• Tablet computers
• Micro computers
• PCs and laptops equipped with wireless network

adapters can connect to these networks as well

Data Transfer
on a LAN

Serial Data Transfer


• Depends on type of connection

1
0
0
1
1
0
1
0
1
1
1

1
0
0
1
1
0

1
0
1
1
1

Transfer of one bit at a time
• Data can travel in a single bit
stream in both directions


How fast does data travel?


A data transfer rate is the maximum bits per second
(bps) that can be transmitted over a network
• Signified with a lowercase b
• The lowercase b differentiates bits from bytes

10
Mbps

BITRATE

Data transfer in LANs - Sending
Before data is transferred, it has
to go through the following
process:

Frame
Packet

Large chunks of data are broken into
segments
2. Addressing information is added to
each segment, making it a packet
1.

Packets then travel to the network
adapter, where a little more
information is added and they become
Ethernet frames.
4. Each frame is then broken into a data
stream of bits – 0s and 1s – that
travel over physical media
3.

IP Address
MAC
Address

Data transfer in LANs - Receiving
When data is received, it goes
through the process in reverse:
1.
2.

3.

The receiving computer reassembles
the bits into an Ethernet frame
It removes the frame information, and
checks the packet information to
make sure it was the intended
recipient
The packet information is then
stripped, and the data segment is
reassembled into the file that we click
on in Windows Explorer

Frame
Packet

How does data know where to go?
Most every computer and many other devices have an Internet
Protocol (IP) address
• Uniquely identifies a device and its associated network

A typical example of an IPv4 address would be 192.168.1.1
Every IP address is broken down into two parts by a subnet
mask
• Network ID 192.168.1
• Host ID 1

Subnet Mask
A group of four numbers that define a computer’s network
• NOTE: All of the 255s in a subnet mask collectively refer to
the network portion, whereas the 0s refer to the host portion


Type of
Address

First Octet

Second
Octet

Third Octet Fourth
Octet

IP Address

192

168

1

1

Subnet Mask

255

255

255

0

Types of Local
Area Networks

Wired LANs (WLANs)
Hosts, such as PCs or laptops,
are connected to central
connecting devices by copperbased twisted pair cabling

Wired LANs (WLANs)
Hosts connect to networks
through WAPs
• To connect to a WAP, a
device must have a wireless
network adapter
• In larger WLANs, the WAP has
to connect to a wired switch


Virtual LANs (VLANs)
With VLANs, devices in a LAN
are grouped based on their
function
Implemented to:

VLAN20

STUDENTS
VLAN30

VLAN30

TEACHERS

TEACHERS

• organize networks
• enhance performance
• increase security

Physical location of devices
does not matter

STUDENTS

VLAN20

Perimeter Networks
Perimeter networks, or
demilitarized zones
(DMZs), are small LANs that
are set up outside of an
organization’s LAN
• DMZs typically consist of
servers that provide services,
like web hosting or email
• This setup allows users
outside of an organization’s
LAN to access the servers,
but not the organization’s


Internet

perimeter

LAN

network

Summary
1

Local Area Networks

2

Data Transfer on a LAN

3

Types of Local Area Network

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