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1.4 WIRED AND WIRELESS NETWORKS LESSON 2 © OCR 2016 The Big Picture: Wired and wireless networks • • • Types of networks: LAN (local area network) & WAN (wide area network) The different roles of computers in a client-server and a peer-to-peer network • Factors that affect the performance of networks • Network topologies The hardware needed to connect stand-alone computers into a local area network: • Wireless access points • Routers/switches • NIC (network interface controller/card) • Transmission media The internet as a worldwide collection of computer networks: • DNS (domain name server) • Hosting • The cloud • The concept of virtual networks © OCR 2016 Thought for the day - Networks At peak capacity, Netflix uses 1/3 of all Internet traffic in North America! © OCR 2016 Starter: Recap P2P and C-S Peer to Peer? 1 -Each computer acts as a 'host'. Users can access files and peripherals directly from all the other nodes on the network. 2 -The files are stored on the hard disks of individual network machines. 3 -Workstations cannot normally 'see' or share data with each other directly over the network. 4 - Users will have their own private area on the network where they can save their files and documents. No one else can access this area (except the network manager/staff). Client – Server? 5 - Each computer on the network has equal importance and no more privileges than any other. 6 - All computers on the network connect through a central hub or switch. 7 - Very common in small offices or at home where there are only a few computers connected together. 8 - There may be multiple shared folders on a server with different access rights. © OCR 2016 Starter: Recap - Network Types Network Meaning Example LAN WAN PAN VPN © OCR 2016 Starter: Recap - Network Types Network LAN WAN PAN VPN Meaning Local Area Network Wide Area Network Personal Area Network Virtual Private Network Example School Cash Dispensers Laptop Mobile © OCR 2016 Learning Objectives By the end of today’s lesson, you will: • Identify the components required to create a LAN • Describe the role of each component in a LAN • Understand what is meant by the performance of a network and why this is important • Explain the factors that can affect the performance of a network © OCR 2016 Transfer of data over a network: Packets • Data transmitted over a network is broken down into packets. • Each packet contains the address of the sender and the address of the receiver (IP addresses) • Packets will also contain a sequence number so they can be re-packaged at the receiving end • Packets will have a time to live (how many hops around the network they can take before they disappear © OCR 2016 Network Performance Latency • Network latency is how much • Describes how much data time it takes for a packet of can be transferred over a data to get from one connection in a given time. designated point to another. • The speed of a network is • Latency is measured by measured in bits per sending a packet that is second. returned to the sender; the • Ideally you would want as round-trip time is considered much bandwidth as possible the latency. to enable as much data as • Ideally, latency is as close to possible to be transferred zero as possible. within that second Bandwidth © OCR 2016 Latency • Network latency is any kind of delay that happens in data communication over a network. • So you want a network with low latency as this will mean there is less of a delay in data communication between devices. • Latency prevents the data from taking full advantage of the available bandwidth. The problem could be temporary or ongoing depending on the issue. Possible contributors to network latency include: • Problems with the transmission medium itself. • Errors with the router or switches as each gateway takes time to examine and change the packet header for the next part of the packets journey. • Anti-virus and similar security processes • The time it takes for a packet to physically travel from its source to a destination. • Storage delays when packets are subject to storage or disk access delays at devices like switches and bridges. • Software malfunctions at the user level can cause some delays from a user perspective. © OCR 2016 Brainstorm • What hardware do we need to create a LAN? • How will the computers be connected together and what might be required to do this? • What do we mean by the performance of a network and why this might be important? © OCR 2016 Hardware components What is the role of the following hardware components in a network? • Wireless access point (WAP) • Router • Switch • Network interface card (NIC) • Transmission media © OCR 2016 Bandwidth • Bandwidth is also defined as the amount of data that can be transmitted in a fixed amount of time. • A LAN has bandwidth in the same way as a WAN such as the Internet has. • Your broadband provider will give you an idea of what your bandwidth is, often quoting the maximum available. © OCR 2016 Network Hardware • https://youtu.be/PPr9Oa_jj1Q?list=PLCiOXwirraUAv kTPDWeeSqAKty3LAG37- © OCR 2016 Wireless Access Point (WAP) • Allows for wireless devices to connect to a network (either LAN or WAN) • Includes connections through Wifi and Bluetooth • WAPs provide Internet access in public places (often known as Wi-Fi hotspots) © OCR 2016 Router • An interconnection device used on networks to connect two or more devices. • Routers contain a routing table which has a list of IP addresses and common routes for packets to take • Routers examine packets IP addresses • The router will apply a subnet mask to identify a network and determine which network the packet should be forwarded to • If the packet is for this network – the router determines which host to send the packet to • Routers allow packets from different network types to be exchanged © OCR 2016 Switch • If two or more computers place a packet onto a network at the same time – a data collision occurs • A switch is an interconnection device that connects two or more devices together and helps in solving the issue of data collisions • As a data packet arrives at the switch – its destination address is examined and the switch creates a direct connection to that device • As far as the two devices are concerned there are no other computers on the network (see example) © OCR 2016 NIC Network Interface Card • A network interface card allows a computer to connect to a wired network • A NIC allows data packets to travel to and from a computer • A NIC contains a MAC address which is a physical hardware address • A NIC allows an Ethernet cable to be plugged into this © OCR 2016 Transmission Media • Ethernet (Cat 5e / Cat6) • Known as twisted pair • A networking standard • Fibre optic • Very fast cable but also more expensive (often used with WAN or larger LANs) • Coaxial Cable • An older networking standard © OCR 2016 Show your understanding 1. Match up the hardware term and its definition on the worksheet. © OCR 2016 Network performance Measures of computer network performance are commonly stated in units of bits per second (bps). This quantity can represent either an actual data rate or a limit to available network bandwidth. Modern networks support very large numbers of bits per second. Instead of quoting 10,000 or 100,000 bps, networks normally express these quantities in terms of kilobits, megabits, and gigabits. •1 Kbps = 1 kbps = 1 kilobit per second = 1,000 bits per second •1 Mbps = 1,000 Kbps •1 Gbps = 1,000 Mbps In networking, both "kbps" with a lowercase "k" and “ Kbps" with an uppercase "K" can be used interchangeably. https://www.youtube.com/watch?v=vTP6mdC w1uE&list=PLCiOXwirraUAvkTPDWeeSqAKty 3LAG37-&index=12 © OCR 2016 Show your understanding 1. Match up the hardware term and its definition on the worksheet. 2. Create a leaflet for a networking novice to explain: • The hardware components and their functions • How they can get the best out of their network explain the factors that can affect the performance of a network and how these can possibly be overcome. © OCR 2016 Plenary: Define Key Words • • • • • • LAN • Packet Wireless access point (WAP) • Router • Switch Ethernet cable Network interface card (NIC) Transmission media Network performance © OCR 2016