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Data communication and Computer Networks

Data communication and Computer Networks. Computer Networks. A computer network is a network of geographically distributed multiple computers, connected in a manner to enable meaningful transmission and exchange of information among them.

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Data communication and Computer Networks

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  1. Data communication and Computer Networks www.AssignmentPoint.com

  2. Computer Networks • A computer network is a network of geographically distributed multiple computers, connected in a manner to enable meaningful transmission and exchange of information among them. • Sharing of information, sharing of resources (both hardware and software), and sharing of processing load, are some of the majorobjectives of a computer network. www.AssignmentPoint.com

  3. Basic Elements of a Communication System • Communication is a the process of transferring messages from one point to another. • Tree basic elements of any communication system are • A sender (source), which creates the message to be transmitted. • A medium, which carries the message • A receiver (sink) www.AssignmentPoint.com

  4. Medium Receiver (sink) Sender (source) Carries the message Receive the message Create the message Figure: Basic elements of a communication system www.AssignmentPoint.com

  5. Receiver Receiver (or sender) Receiver (or sender) Sender Sender (or receiver) Sender (and receiver) (a) Simplex (b) Half duplex (c) Full duplex Data Transmission Modes • Simplex – signal travels in only one direction • Half duplex – signal travels in both directions, but only one direction at a time • Full duplex – signal travels in both directions at the same time www.AssignmentPoint.com

  6. Data Transmission Speed • A term used to describe the data-handling capacity of a communication system is bandwidth. • A bandwidth is the range of frequencies that is available for the transmission of data. • The communication data transfer rate is measured in a unit calledbaud. • In general usage, baud is identical to bits per second. For instance, a rate of 300 baud is 300 bits per second. www.AssignmentPoint.com

  7. Data Transmission Speed • Depending on their transmission speeds, communication channels (paths) are grouped into the following three basic categories : • Narrowband :Narrowband or subvoice grade channels rang in speed from 45 to 300 baud. They are used for handling low data volumes, and are adequate for low-speed devices. They are used mainly for telegraph lines and low speed terminals. • Voice band :Voice band channels handle moderate data volumes, and can transmit data at speed up to 96 baud. They are so called because their major application is for ordinary telephone voice communication. They are also used for data transmission from slow I/O devices to CPU or voice versa. Moreover, most remote terminals are connected to computers through voice band channels. www.AssignmentPoint.com

  8. Data Transmission Speed • Broadband:Broadband or wideband channels are used when large volumes of data are to be transmitted at high sped. These system provides data transmission rates of 1 million baud or more. A company might use a broadband facility for high speed computer-to-computer communication, or for simultaneous transmission of data to several different devices. www.AssignmentPoint.com

  9. How does data travel over a network? www.AssignmentPoint.com

  10. Data Transmission Media • Some of the most common data transmission media are described below: • Twisted-Pair Wire • Coaxial Cable • Microwave • Communication Satellite • Optical Fibers www.AssignmentPoint.com

  11. Twisted-Pair Wire • Today’s networks use twisted-pair cables • UTP (unshielded twisted pair) • STP (shielded twisted pair) • Looks similar to telephone cable • Has square plastic RJ-45 connector www.AssignmentPoint.com

  12. Coaxial Cable • Another option is coaxial cable • Resembles cable-TV cable • Round, silver BNC or F-type connector www.AssignmentPoint.com

  13. Fiber-optic cable is a bundle of extremely thin strands of glass • Each optical fiber (strand) is thinner than a human hair • USB, serial, parallel, SCSI, and Firewire connections www.AssignmentPoint.com

  14. Network Topologies • The term network topology refers to the way in which the nodes of a network are link together. • It determine the data paths, which may be used between any pair of nodes in the network. • The choice of network topology for installing a computer network depends upon a combination of factors, such as : • The desired performance of the system • The desired reliability of the entire system • Size of the system www.AssignmentPoint.com

  15. Network Topologies • Expandability of the system • Cost of the components and services required to implement the network • Availability of communication lines • Delays involved in routing information from one node to another. www.AssignmentPoint.com

  16. Network Topologies • The number of possible network topologies is seemingly limitless, the four major ones are • Star Network • Ring Network • Completely connected Network • Multi-access bus Network www.AssignmentPoint.com

  17. Host computer Star Network A star configuration of computer network www.AssignmentPoint.com

  18. Advantages and disadvantages of star network • Advantages: • Star topology has minimal line cost because only n-l lines are required for connecting n nodes. • Transmission delays between two nodes do not increase by adding new nodes to the network, because any two nodes may be connected via two links only. • If any of the total computers fails, the remaining portion of the network is unaffected. • Disadvantage:The system crucially depends on the central node. If the host computer fails, the entire network fails. www.AssignmentPoint.com

  19. Ring Network A ring configuration of computer network www.AssignmentPoint.com

  20. Advantages of Ring Network • The ring network works well where there is no central-site computer system • It is more reliable than a star network because communication is not dependent on a single host computer. If a link between any two computers breaks down, or if one of the computer breaks down, alternate routing is possible www.AssignmentPoint.com

  21. Disadvantages of Ring Network • In a ring network, communication delay is directly proportional to the number of nodes in the network. Hence, addition of new nodes in the network increase the communication delay. • The ring network requires more complicated control software than star network www.AssignmentPoint.com

  22. Completely Connected Net work www.AssignmentPoint.com

  23. Advantages of Completely Connected Net work • This type of network is very reliable, as any link breakdown will affect only communication between the connected computers. • Each node of the network need not have individual routing capability • Communication is very fast between any two nodes www.AssignmentPoint.com

  24. Disadvantages of Completely Connected Net work • It is the most expensive network from the point of view of link cost. If there are n nodes in the network, n(n-1)/2 links are required. Hence, the cost of linking the system grows with the square of the number of nodes. www.AssignmentPoint.com

  25. Computer Single communication line shared by all nodes A Multi-access Bus Network www.AssignmentPoint.com

  26. Advantages of Multi-access Bus Network • It helps in reducing the number of physical lines. • The failure of a computer does not affected the communication among other computers in the network. • Addition of new computers to the network is easy www.AssignmentPoint.com

  27. Disadvantages of Multi-access Bus Network • All computers in the network must have good communication and decision-making capability. • If all communication line fails, the entire breaks down www.AssignmentPoint.com

  28. Network Type • LAN, WAN, MAN • LAN technologies are standardized by the Institute of Electrical and Electronics Engineers • IEEE designation numbers help identify compatible network technologies • IEEE 802.3 www.AssignmentPoint.com

  29. What is Wi-Fi? • Wireless LANs are slower but eliminate unsightly wires • Signals can be disrupted by large metal objects, cell phones, pagers, and other wireless devices • Most popular is 802.11 sometimes called WiFi for “wireless fidelity” • Range of up to 150 feet • Bluetooth • 1 Mbps, range of 30 feet www.AssignmentPoint.com

  30. LAN Installation: How do I set up a simple LAN? • First make sure every PC contains an Ethernet port • Next, attach each workstation to a hub • With all workstations connected, turn them on • Windows should automatically detect the Ethernet cards and establish a connection to the network www.AssignmentPoint.com

  31. LAN Installation: How do I set up a simple LAN? www.AssignmentPoint.com

  32. PROTOCOL • A protocol is a set of rules for efficiently transmitting data from one network node to another • The best-known protocol is probably TCP/IP www.AssignmentPoint.com

  33. What is ARCnet? • One of the oldest, simplest, and least expensive LAN technologies • Original ARCnet standard supported transmission rates of 2.5 Mbps • Later versions supported 20 and 100 Mbps transmission rates • Permits mixed transmission media www.AssignmentPoint.com

  34. NAP NAP Links maintained by AT&T Links maintained by Sprint High-speed AT&T routers High-speed Sprint routers To ISP To ISP How is the Internet structured? www.AssignmentPoint.com

  35. What kinds of network devices are part of an ISP? www.AssignmentPoint.com

  36. Internet Protocols: Why odes the Internet use TCP/IP? • Provides a standard that is fairly easy to implement, public, free, and extensible • The Internet is not owned, operated, or controlled by any single entity • TCP/IP is glue that holds the Internet together www.AssignmentPoint.com

  37. Is TCP/IP the only Internet Protocol? www.AssignmentPoint.com

  38. IP Addresses: Does the Internet use a special addressing scheme? • The IP part of TCP/IP defines the format for the addresses that identify computers on the Internet. • These addresses are called IP addresses. • An IP address is a series of numbers, such as 204.127.129.001 • It is separated into four sections by periods • Each section’s number cannot exceed 255 • Each address requires 32 bits (8 bits per section) www.AssignmentPoint.com

  39. Do I need a permanent IP address? • Static IP address – permanently assigned IP address • Dynamic IP address – temporarily assigned • ISPs need static IP addresses • Clients typically use dynamic IP addresses as the IP addressing scheme provides approximately only 4.3 billion unique addresses www.AssignmentPoint.com

  40. Domain Names: What’s a domain name? • People find it difficult to remember long strings of numbers, so host computers also have names called domain names • Domain name – “fully qualified domain name” (FQDN), usually typed in all lowercase • Key component of URLs and e-mail addresses • www. msu.edu/infotech - www.msu.edu is the domain name www.AssignmentPoint.com

  41. Top-level Domains: biz com edu gov info int mil net org Domain Names: What’s a domain name? www.AssignmentPoint.com

  42. How are domain names related to IP addresses? • Each name corresponds to an IP address • Domain name system – Huge database that houses the names and IP addresses • Domain name servers – Computers that house the database www.AssignmentPoint.com

  43. How do I get a domain name? www.AssignmentPoint.com

  44. Is a fee required to obtain a domain name? • You can register a domain name for a minimal annual fee ($10 - $50) • Some Internet entrepreneurs have registered high-profile domain names and resell them • team.com - $250,000 • science.tv - $100,000 www.AssignmentPoint.com

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