Networks

Name that topology! Tree

Name that topology! Ring

Topologies, such as the Ring Topology, can have redundancy built in so that if one node fails data can travel an alternate route to the destination

Name that topology! Bus

Name that topology! Mesh

Name that topology! Star

What does MAN stand for? Metropolitan Area Network

What does NAN stand for? Neighborhood Area Network

What does LAN stand for? Local Area Network

What does WAN stand for? Wide Area Network

What does PAN stand for? Personal Area Network

5 Chapter 5: LANs and WLANs 13 Network Links  A communications channel, or link, is a physical path or frequency for signal transmissions  Bandwidth is the transmission capacity of a communications channel –Broadband –Narrowband

5 Chapter 5: LANs and WLANs 14 Communications Protocols  A packet is a “parcel” of data that is sent across a computer network –Circuit-switching technology vs. packet switching technology

Circuit Switching Dedicated communication path between two nodes Inefficient Path capacity dedicated for duration of connection example: telephone system

Packet Switching efficient Single node to node link can be shared by many packets over time example: internet

5 Chapter 5: LANs and WLANs 17 Communications Protocols  Rules for efficiently transmitting data from one network node to another –Divide messages into packets –Affix addresses to packets –Initiate transmission –Regulate flow of data –Check for transmission errors –Acknowledge receipt of transmitted data

5 Chapter 5: LANs and WLANs 18 Communications Protocols  Every packet that travels over a network includes the address of its destination device  A MAC address is a unique number assigned to a network interface card when it is manufactured  An IP address is a series of numbers used to identify a network device  IP addresses can also be obtained through DHCP

DHCP Stands for Dynamic Host Configuration Protocol It is an auto-configuration protocol used on IP networks. Computers that are connected to IP networks must be configured before they can communicate with other computers on the network. DHCP allows a computer to be configured automatically, eliminating the need for intervention by a network administrator. It also provides a central database for keeping track of computers that have been connected to the network. This prevents two computers from accidentally being configured with the same IP address

5 Chapter 5: LANs and WLANs 20 Wired Network Basics  A wired network uses cables to connect network devices  Wired networks are fast, secure, and simple to configure  Devices tethered to cables have limited mobility

5 Chapter 5: LANs and WLANs 21 Ethernet  Simultaneously broadcasts data packets to all network devices –IEEE –CSMA/CD protocol  Vary in speed from 10Mbps to 100Gbps

Ethernet is the most widespread wired LAN technology

5 Chapter 5: LANs and WLANs 23 Ethernet On an Ethernet, data travels on a first-come, first-served basis. If two workstations attempt to send data at the same time, a collision occurs. That data must be resent.

5 Ethernet Equipment Chapter 5: LANs and WLANs 24

5 Chapter 5: LANs and WLANs 25 Ethernet Equipment  Ethernet adapter (designed to support the Ethernet protocols)  Network hub  Network switch  Network router  RJ45 connector

Hubs, Switches, & Routers Hub: basic networking component used to connect computers to form a LAN – a data packet coming from one port is sent to all other ports – basically organizes your cables and relays data signals to all computers on the LAN

Hubs, Switches, & Routers Switch: networking device that controls the flow of data by using the MAC address that is placed on each data packet – Switches divide networks into Virtual LANS (VLAN) – becoming very popular on both small and large networks

Hubs, Switches, & Routers Router: utilize a combination of hardware/software to actually route data from source to destination – utilizes IP addresses – divides large networks into logical segments called subnets

5 Ethernet Setup Chapter 5: LANs and WLANs 29 Most routers are configured using a browser. You should change the network administrator password, then verify that DHCP is enabled

5 Chapter 5: LANs and WLANs 30 Wireless Basics  A wireless network transports data from one device to another without cables or wires  Slower than wired networks  Security concerns

5 Chapter 5: LANs and WLANs 31 Bluetooth  Bluetooth is a short-range, wireless network technology designed to make its own connections between electronic devices, without wires, cables, or any direct action from a user

Bluetooth Key Features -Robustness -Low power consumption -Low cost

Bluetooth 2010 Bluetooth Innovation World Cup Winner Pervasive Computing Group at Imperial College London, Great Britain, proposed a small sensor worn on a person's ear that's able to measure balance, body posture, activity level, and heart rate, and then transmit that information wirelessly to a computer or other device where it could be viewed by the patient's health care provider. Because the ear sensor would have to be very small and light, it would need to be low power. This is possible if the sensor is designed using Bluetooth low energy technology. Excerpt from

Bluetooth Excerpt from Biju Thomas of the United States proposed an impact sensor capable of providing detailed measurements of shocks in sports accidents, such as a helmet that tells you how hard you hit your head when you fell while skiing. The severity of impact could be measured and transmitted to a mobile phone using Bluetooth low energy technology. This could help detect head injuries that seem minor, but turn out to be much more severe than a person realizes. Such impacts could be detected immediately and trigger an alarm message sent to a mobile phone. It could even help people who are knocked unconscious, by automatically dialing a pre-programmed emergency number and delivering a pre-recorded message that includes the location of the injured person. A person would have 30 seconds to turn off the alarm and prevent the emergency call from being made.

Bluetooth Excerpt from Christopher Allen of the United States proposed a barbecue that could be controlled by aBluetooth enabled remote control. Allen's "iGrill" application would send information from your grill to your Apple iPhone, iPad or iPod Touch over a relatively long-range using Bluetoothtechnology. So you could relax with your guests while checking the status of your grilling food on your handheld device.

5 Chapter 5: LANs and WLANs 36 Wi-Fi Equipment  If your computer is not pre-equipped with wireless circuitry, you can purchase and install a Wi-Fi card

5 Chapter 5: LANs and WLANs 37 Sharing Files  If you use Windows, it automatically detects available LANs any time you turn on a workstation  To connect to a shared resource, you might be asked for a user ID and password

5 Chapter 5: LANs and WLANs 38 Troubleshooting  Network problems can stem from a variety of sources –Cables –Signal strength –Security –Interference –Network devices –Settings

Security

5 Chapter 5: LANs and WLANs 40 Wi-Fi Security  Wireless networks are much more susceptible to unauthorized access and use than wired networks  LAN jacking, or war driving, is the practice of intercepting wireless signals by cruising through an area

5 Chapter 5: LANs and WLANs 41 Wi-Fi Security  Wireless encryption scrambles data transmitted between wireless devices and then unscrambles the data only on devices that have a valid encryption key –WEP (Wired Equivalent Privacy) –WPA (Wi-Fi Protected Access) –WPA2 –PSK  Activate encryption by using a wireless network key

5 Chapter 5: LANs and WLANs 42 Encryption  Encryption transforms a message so that its contents are hidden from unauthorized readers –Plaintext has not yet been encrypted  Decryption is the opposite of encryption –Cryptographic algorithm –Cryptographic key

5 Chapter 5: LANs and WLANs 43 Encryption  Weak vs. strong encryption  AES (Advanced Encryption Standard) –standard adopted by the U.S. government  Encryption methods can be broken by the use of expensive, specialized, code-breaking computers –Brute-force method

5 Chapter 5: LANs and WLANs 44 Encryption  Public key encryption (PKE) eliminates key-distribution problem, by using one key to encrypt a message and another key to decrypt the message

PKE (Public Key Encryption) You can think of it as a locked front door to a building, and the door has a mail slot – Mail slot is exposed and accessible to the public; its location (street address) is like the public key – Anyone knowing the address can go to the door and drop a message through the slot – Only the person possessing the matching private key (owner of the building) can open the door and read the message

War Driving the act of searching for wireless networks by a person in a moving vehicle using a portable computer or PDA Story on war driving: mber/war_spammer mber/war_spammer111004

HTTPS You may have seen HTTPS at the beginning of the URL while doing online shopping, banking, etc. HTTPS stands for Hypertext Transfer Protocol Secure It utilizes the SSL/TLS protocol to provide encrypted communication and secure identification of a network web server

What does VPN stand for? Virtual Private Network

What does ISP stand for? Internet Service Provider