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

2. Agenda 1 Local Area Networks 2 Data Transfer on a LAN 3
Types of Local Area Network

3. Local Area Networks

4. 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

5. 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

6. 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

7. 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

8. What devices make up LANs?
Hub
Switch
Router
Laptops
Phones
Desktop PCs
Servers
Tablets
HOSTS
CENTRAL CONNECTING DEVICES

9. 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

10. 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

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

12. 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

13. 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

14. 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)

15. 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

16. 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

17. Data Transfer on a LAN

18. Serial Data Transfer Transfer of one bit at a time1
Transfer of one bit at a time
Data can travel in a single bit stream in both directions
Depends on type of connection

19. 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

20. Data transfer in LANs - Sending
Before data is transferred, it has to go through the following process:
Large chunks of data are broken into segments
Addressing information is added to each segment, making it a packet
Packets then travel to the network adapter, where a little more information is added and they become Ethernet frames.
Each frame is then broken into a data stream of bits – 0s and 1s – that travel over physical media
Frame
Packet
IP Address
MAC Address

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

22. 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
Every IP address is broken down into two parts by a subnet mask
Network ID
Host ID 1

23. 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
Subnet Mask
255

24. Types of Local Area Networks

25. Wired LANs (WLANs)
Hosts, such as PCs or laptops, are connected to central connecting devices by copper-based twisted pair cabling

26. 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

27. Virtual LANs (VLANs)
With VLANs, devices in a LAN are grouped based on their function
Implemented to:
organize networks
enhance performance
increase security
Physical location of devices does not matter
VLAN20
VLAN30
TEACHERS
STUDENTS

28. Perimeter Networks
Internet
perimeter
network
LAN
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
This setup allows users outside of an organization’s LAN to access the servers, but not the organization’s LAN

29. Summary 1 Local Area Networks 2 Data Transfer on a LAN 3
Types of Local Area Network

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