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Various types of Networks and their characteristics

Various types of Networks and their characteristics 6
Chapter 15 NetworksChapter Goals • Describe the core issues related to computer networks • List various types of networks and their characteristics • Explain various topologies of localarea networks • Explain why network technologies are best implemented as open systems • Compare and contrast various technologies for home Internet connections 2Chapter Goals • Explain packet switching • Describe the basic roles of various network protocols • Explain the role of a firewall • Compare and contrast network hostnames and IP addresses • Explain the domain name system • Describe cloud computing and its benefits 3Networking Computer network A collection of computing devices connected in order to communicate and share resources Connections between computing devices can be physical using wires or cables or wireless using radio waves or infrared signals Can you name some of the devices in a computer network 4Networking Node (host) Any device on a network Data transfer rate (bandwidth) The speed with which data is moved from one place to another on a network Why is bandwidth so key 5Networking Computer networks have opened up an entire frontier in the world of computing called the client/server model 6Networking Protocol A set of rules that defines how data is formatted and processed on a network File server A computer dedicated to storing and managing files for network users Web server A computer dedicated to responding to requests for web pages P2P model A decentralized approach that shares resources and responsibilities among many “peer” computers 7Types of Networks Localarea network (LAN) A network that connects a relatively small number of machines in a relatively close geographical area Ring topology connects all nodes in a closed loop on which messages travel in one direction Star topology centers around one node to which all others are connected and through which all messages are sent Bus topology nodes are connected to a single communication line that carries messages in both directions 8Types of Networks Ethernet The industry standard bus technology for localarea networksTypes of Networks Widearea network (WAN) A network that connects localarea networks over a potentially large geographic distance Metropolitanarea network (MAN) The communication infrastructures that have been developed in and around large cities Gateway One particular set up to handle all communication going between that LAN and other networks 10Types of Networks 11Types of Networks Internet A wide area network that spans the planet So, who owns the Internet 12Internet Connections Wireless network A network in which devices communicate with other nodes through a wireless access point Bluetooth A technology used for wireless communication over short distances 13Internet Connections Internet backbone A set of highspeed networks that carry Internet traffic, provided by companies such as ATT, Verizon, GTE, British Telecom, and IBM Internet service provider (ISP) An organization providing access to the Internet 14Internet Connections Various technologies available to connect a home computer to the Internet Phone modem converts computer data into an analog audio signal for transfer over a telephone line, and then a modem at the destination converts it back again into data Digital subscriber line (DSL) uses regular copper phone lines to transfer digital data to and from the phone company’s central office Cable modem uses the same line that your cable TV signals come in on to transfer the data back and forth 15Internet Connections Broadband A connection in which transfer speeds are faster than 768 kilobits per second – DSL connections and cable modems are broadband connections – The speed for downloads (getting data from the Internet to your home computer) may not be the same as uploads (sending data from your home computer to the Internet) 16Packet Switching Packet A unit of data sent across a network Router A network device that directs a packet between networks toward its final destination Packet switching Messages are divided into fixedsized, numbered packets; packets are individually routed to their destination, then reassembledPacket Switching Take a message, break it into three packets, and simulate this process 18Open Systems A logical progression... Proprietary system A system that uses technologies kept private by a particular commercial vendor Interoperability The ability of software and hardware on multiple machines and from multiple commercial vendors to communicate Open systems Systems based on a common model of network architecture and a suite of protocols used in its implementation 19Open Systems Open Systems Interconnection Reference Model A sevenlayer logical break down of network interaction to facilitate communication standards Each layer deals with a particular aspect of network communication 20Network Protocols • Network protocols are layered such that each one relies on the protocols that underlie it • Sometimes referred to as a protocol stack 21TCP/IP Transmission Control Protocol (TCP) Software that breaks messages into packets, hands them off to the IP software for delivery, and then orders and reassembles the packets at their destination Internet Protocol (IP) Software that deals with the routing of packets through the maze of interconnected networks to their final destination 22TCP/IP User Datagram Protocol (UDP) An alternative to TCP that is faster but less reliable Ping A program used to test whether a particular network computer is active and reachable Traceroute A program that shows the route a packet takes across the Internet 23Traceroute in Action 24HighLevel Protocols Other protocols build on TCP/IP protocol suite Simple Mail Transfer Protocol (SMTP) used to specify transfer of electronic mail File Transfer Protocol (FTP) allows a user to transfer files to and from another computer Telnet used to log onto one computer from another Hyper Text Transfer Protocol (http) allows exchange of Web documents Which of these have you used 25HighLevel Protocols Port A numeric designation that corresponds to a particular highlevel protocol 26MIME Types MIME type A standard for defining the format of files that are included as email attachments or on websites What does MIME stand for Multipurpose Internet Mail Extension 27Firewalls Firewall A gateway machine and its software that protects a network by filtering the traffic it allows Access control policy A set of rules established by an organization that specifies what types of network communication are permitted and denied Have your messages ever been returned undelivered, blocked by a firewall 28Firewalls 29Network Addresses Hostname A name made up of words separated by dots that uniquely identifies a computer on the Internet IP address An address made up of four onebyte numeric values separated by dots that uniquely identifies a computer on the Internet Is there a correspondence between the parts of a hostname and an IP address 30Network Addresses What is wrong with the IP4 strategy How did smartphones contribute to the problem 31Network Addresses IPv4 The last block was assigned in 2011 IPv6 32 bits organized into 4 groups of 8 FE80:0000:0000:0000:0202:B3FF:FE1E:8329 They work in parallel 32Domain Name System Host number The part of the IP address that specifies a particular host (machine) on the network Yes, but what is it Domain name The part of a hostname that specifies a specific organization or group Toplevel domain (TLD) The last section of a domain name that specifies the type of organization or its country of origin 33Domain Name System Domain name system (DNS) A distributed system for managing hostname resolution Domain name server A computer that attempts to translate a hostname into an IP address Domain Squatting Ransoming domain names Should the tables containing hostname/IP mappings be sorted or unsorted Why 34Domain Name System 35Domain Name System Organizations based in countries other than the United States use a toplevel domain that corresponds to their twoletter country codes Have you emailed someone in another country 36Domain Name System A very small, random selection of new TLDs that are available as of mid2014 37Who Controls the Internet Control of IP addresses and domain names • Internet began as ARPANET, a project of the US Dept. of Defense • Control subcontracted to ICANN in 1998 • US gov’t to further reduce role as early as 2015 FCC proposal • Would allow ISPs to provide “premium” access to certain customers, perhaps by deliberately slowing down data transfer for others • Net neutrality The principle that ISPs should deliver data to everyone equally, as fast as the technology allows 38Cloud Computing • Public clouds are accessible by any subscriber • Private clouds are established for a specific group or organization • Community clouds are shared among two or more organizations with the same needs • Hybrid clouds are some combination of the others 39Ethical Issues Effects of Social Networking What are some examples of popular social networking sites Who uses social networking What are the benefits and the disadvantages of using these social networking sites Do the benefits of social networking out weigh the potential costs 40Who am I What two major awards did I win For what were they given 41Do you know What is SETI What does it have to do with extraterrestrials What is a protocol For what did Bill Gates receive a Knighthood from Queen Elizabeth The Kernel suggested that the causes of death for a South Korean man in 2005 and a Taiwanese man in 2012 were the same. What was the suggested cause 42
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