Transcript CHAPTER 6
Telecommunications, P.II AIMS 2710 R. Nakatsu Telecommunications, P. II: An Overview Network technologies and concepts include: Networking devices (switches, routers repeaters, access points) Wireless networks – Wi-Fi – Cellular networks Last mile broadband Internet/networking protocols Virtual Private Networks (VPNs) Network Latency Refers to the amount of time that it takes a packet to get to its destination. It represents the lag, or delay in communications, between your computer and another (target) computer. A ping test can be used to measure latency. Having low latency (i.e. fast response) is especially important where real time, two-way communications are required. Networking Devices are the hardware devices that unite the various media and computers and route data and communications throughout a network. Three Examples: 1. NETWORK SWITCH – A device containing multiple ports that enable you to connect computers, printers, servers and other devices to a network. A switch serves as a controller, enabling networked devices to talk to each other efficiently within a local network. Network Switch: Central Connection Point of a Network Networking Devices, P. II 2. ROUTER – A networking device that connects two or more networks: it routes packets of data from one network to another. The router ensures that information doesn't go where it's not needed. The router makes sure that information does make it to the intended destination. Demo Question: What is the difference between a router and a switch? 3. REPEATER – a device that gives your network signals a boost. Wireless Networks: Wi-Fi How do WiFi hot spots work? – Wireless network adapter – Access points 1. A computer’s wireless network adaptor translates data into a radio signal and transmits it. 2. The access point has an antenna that receives the signal and decodes it. It sends the information to the Internet using a cabled connection. 3. As a rule of thumb, the range is about 150 ft (indoors) and 300 ft (outdoors) The process also works in reverse (can send radio signals to connected devices). Wireless Networks: Cellular Networks 3G Cellular Networks offer access speeds usually less than 2 MBPS (download). Two standards: CDMA and GSM. 4G Cellular Networks offer average speeds from 5 to 12 MBPS (download). LTE is the new global 4G wireless standard. SIM cards: What are these? M-commerce (mobile-commerce) – Widespread use of mobile devices (smartphones & tablets) to buy and purchase over the Internet. Square Demo Benefits of Wireless Networks They are comparatively cheaper to set up than wired networks. Wired networks may require drilling through walls and running cables through ceilings. A few well-placed wireless access points (or building a mesh network) can reach far more devices than a wired network. Obviously, you have more mobility using a wireless network. Question: Are there disadvantages of wireless networks? Wireless Mesh Networks In a wireless mesh network, a network connection can be spread across dozens or even hundreds of wireless mesh nodes that “talk” to one another. Each node is an access point with a radio transceiver. Last Mile Broadband When considering overall network speed remember Amdahl’s Law: a system’s speed is determined by its slowest component. The bottleneck is the so-called last mile, or the connection that customers use to get online. Three types of last mile broadband: 1. DSL (digital subscriber line) uses the copper wire the phone company has already installed. 2. Cable Broadband uses the cable network. 3. Fiber to the home (FTTH) is the fastest last mile broadband (e.g., Verizon’s FiOS technology). Internet/Networking Protocols A protocol is a standard set of rules and procedures for the control of communications in a network. Open Systems use common standards for hardware, software, applications, and networking. Proprietary Systems are closed systems that are owned and controlled by a single company. What are some examples of each type? The Great Debate of the Digital Age Open vs. Closed (Proprietary) Which is the better strategy? Some Networking Protocols Some Examples: Ethernet (LAN protocol): wired connections to a network Transmission Control Protocol / Internet Protocol (TCP/IP): Internet standard Wireless Protocols: Bluetooth (low-cost wireless protocol with a range of about 30 feet) Wi-Fi (standard for wireless computer networks—see previous slide for more information) LTE (4G standard with larger range and higher data speeds than 3G) Public vs. Private Network Public Network: a network on which your organization competes for time and use with others. Private Network: a network that your organization either owns or exclusively leases the right to use the communications media. What are the benefits of public networks? What are the benefits of private networks? Virtual Private Network (VPN) A secure network that uses the Internet as its main backbone network, but relies on firewalls and other security features. Example application: A VPN would enable a company to use the Internet to establish secure intranets between its distant branch offices and manufacturing plants. A Virtual Private Network The Internet Router Extranet Fire wall Intranet Server Fire wall Router Intranet Server Host System Benefits of VPNs • Extended connections across multiple geographic locations (larger geographic reach). • Improved security for exchanging data. • Savings in time and expense for employees if they don’t have to come into the office to work. Setting up your own VPN Popular VPNs include VyprVPN and HotspotVPN They encrypt all communications you transmit wirelessly and over the Internet. Some encrypt only web activity while others will also encrypt email exchanges.