Module 1: Understanding Local Area Networks 1.2 Understand local area networks (LANs) 1.5 Understand network topologies and access 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? Hub Switch Router Laptops Phones Desktop PCs Servers Tablets HOSTS CENTRAL CONNECTING DEVICES

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 Transfer of one bit at a time 1 Transfer of one bit at a time Data can travel in a single bit stream in both directions Depends on type of connection

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: 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

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

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 Subnet Mask 255

Types of Local Area Networks

Wired LANs (WLANs) Hosts, such as PCs or laptops, are connected to central connecting devices by copper-based 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: organize networks enhance performance increase security Physical location of devices does not matter VLAN20 VLAN30 TEACHERS STUDENTS

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 email This setup allows users outside of an organization’s LAN to access the servers, but not the organization’s LAN

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

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