Computer network-types1
- 2. Networking 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
- 3. Networking… Node Any device on a network Data transfer rate (bandwidth) The speed with which data is moved from one place to another on a network
- 5. Basic Components… Terminals: end user work station Telecommunications Channels & Media: Media over which data are transmitted – coaxial cables, fiber optics etc. Computer: carry out their information processing assignments. Mainframe host computer/server. 5
- 6. Basic Components… Telecommunication Software: controls the telecommunication activities Telecommunication Processors: to enhance data communication b/w two points – modems, message switchers, multiplexers, front end processors 6
- 7. Basic Components… Modems: most common type; convert analog signals to digital and vice versa. Message Switchers: device that receives data messages from terminals, determine their destination and routes them one by one to the CPU. Advantages – reduce long distance transmission costs since only single line is required Multiplexers : collects messages from many senders, puts them in order & transmits them thru a broadband; allows simultaneous transmission 7
- 8. Basic Components… Concentrator : a smart multiplexer, can be programmed, more processing capability (used for load balancing) Controller : link groups (clusters) of terminals to a communication channel Front-end processors: located near the host computer, relieves the host computer of some of the communications tasks, so that it can process other applications requests. 8
- 9. Communications Media Channel: means by which data is transmitted b/w sending and receiving devices. 9
- 10. Types of Networks Local-area 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
- 11. Types of Networks Ethernet The industry standard bus technology for local-area networks
- 12. Types of Networks Wide-area network (WAN) A network that connects local-area networks over a potentially large geographic distance Metropolitan-area 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
- 13. Types of Networks Local-area networks connected across a distance to create a wide-area network
- 14. Types of Networks Internet A wide area network that spans the planet 14
- 15. Network Protocols An agreed-upon format for transmitting data b/w 2 devices. Protocol determines the following Type of error checking Data compression method Message completion indicated by sender Message acknowledgement by receiver Popular protocols – TCP/IP, HTTP, FTP, SMTP, POP 15
- 16. Network Architecture Refer to either h/w, s/w or a combination. Classification : - Peer-to-peer architecture – each workstation has equivalent capabilities & responsibilities Client/Server architecture – each computer is either a client or a server. 16
- 17. Packet Transmission/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 fixed-sized, numbered packets; packets are individually routed to their destination, then reassembled
- 18. Packet Switching Messages sent by packet switching Take a message, break it into three packets, and simulate this process
- 19. Hubs A hub is the place where data converges from one or more directions and is forwarded out in one or more directions. Seen in local area networks
- 20. Switches Allow different nodes of a network to communicate directly with each other. Allow several users to send information over a network at the same time without slowing each other down using Media Access Control address (MAC address)
- 21. TCP/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 21
- 22. High-Level 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 22 Which of these have you used?
- 23. Firewalls- Network Security 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 specify what types of network communication are permitted and denied 23 Have your messages ever been returned undelivered, blocked by a firewall?
- 24. Firewalls 24 A firewall protecting a LAN