Introduction of computer network
•Download as PPT, PDF•
9 likes•2,696 views
Basic definition of computer Network which will brief about types of networks, topology and difference between OSI and TCP/IP.It also elaborate to guided and Unguided media.
Recommended
More Related Content
What's hot
What's hot (20)
Similar to Introduction of computer network
Similar to Introduction of computer network (20)
More from Vivek Kumar Sinha
More from Vivek Kumar Sinha (20)
Recently uploaded
Recently uploaded (20)
Introduction of computer network
- 1. Presented By Vivek Kumar Sinha HOD Department of Computer Science and Engineering 07/11/17
- 2. Overview • Data • Data Communication • Networking • Type of Networks • Protocol Layers • ISO/OSI Reference Model • TCP/IP Reference Model 07/11/17
- 3. Data • Data refers to the raw facts that are collected while information refers to processed data that enables us to take decisions. • Ex. When result of a particular test is declared it contains data of all students, when you find the marks you have scored you have the information that lets you know whether you have passed or failed. 07/11/17
- 4. Data Communication Communication: Two nodes. Mostly EE issues. Networking Networking : Two or more nodes. More issues, e.g.. routing. 07/11/17
- 5. Characteristics of Data Communication The following four fundamental characteristics: • Delivery: The data should be delivered to the correct destination and correct user. • Accuracy: The communication system should deliver the data accurately, without introducing any errors. • Timeliness: Audio and Video data has to be delivered in a timely manner • Jitter: It is the variation in the packet arrival time. Uneven Jitter may affect the timeliness of data being transmitted.07/11/17
- 6. What is a network? A network is a collection of individual computers, connected by some physical media and networking devices. 07/11/17
- 8. Types of networks(cont) Local Area Networks(LAN) 0-2 K.M. single ownership Metropolitan Area Network(MAN) 2-50 K.M. Wide Area Network(WAN): 50+ K.M. Personal area network (PAN):10 meters range. 07/11/17
- 9. Defining LANs, MANs, and WANs Local Area Network (LAN): A LAN supports fast, low−error data transfer on a physical network infrastructure that covers a small, limited geographic area, such as within a single building or on a single floor of a building. Metropolitan Area Network (MAN): A MAN is a network that spans an area larger than a LAN but is less dispersed geographically than a WAN. A MAN network may connect several LANs on a single company's campus, or interconnect the LANs of several companies and businesses in one part of town, Wide Area Networks (WAN): A WAN,, is a network that interconnects LANs and MANs across a broad geographic area 07/11/17
- 10. A Local Area Network 07/11/17
- 11. LAN
- 12. LAN Topologies • Define network device organization • Four common types – Bus topology – Tree topology – Star topology – Ring topology • Topologies are logical architectures – Actual devices need not be physically organized in these configurations
- 13. Bus and Tree Topology ree topology branch” with multiple nodes
- 14. Star Topology (LAN) • Center: hub, repeater, or concentrator • Typically used in both Ethernet and Token Ring • 5 to 100+ devices
- 15. Ring Topology (LAN) Redundant ring to avoid network failure • Repeaters at each component • Unidirectional transmission links • Closed loop • Typically used in FDDI networks
- 16. A Wide Area Network 07/11/17
- 17. • A personal area network (PAN) is the interconnection of information technology devices within the range of an individual person, typically within a range of 10 meters. For example, a person traveling with a laptop, a personal digital assistant (PDA), and a portable printer could interconnect them without having to plug anything in, using some form of wirelesstechnology. Typically, this kind of personal area network could also be interconnected without wires to the Internet or other networks.
- 18. PAN
- 19. Why Network Your Computers? • Users can share resources and communicate File sharing. Hardware sharing (printers, CD-ROM drives, and hard drives ) Program sharing User communication. Multiplayer gaming 07/11/17
- 21. Reasons why a layered−model is used Change: changes made to one layer, the impact on the other layers is minimized. Design: protocol designers can specialize in one area (layer) without worrying about how any new implementations affect other layers. Learning: The layered approach reduces the complexity and makes learning ,understanding the actions of each layer and the model on the whole much easier. 07/11/17
- 22. Troubleshooting: The protocols, actions, and data contained in each layer of the model relates only to the purpose of that layer. This enables troubleshooting efforts to be pinpointed on that layer. Standards: Probably the most important reason for using a layered model is that it establishes a prescribed guideline for interoperability between the various vendors developing products that perform different data communications tasks. 07/11/17
- 24. Devices Function at Layers 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical NIC Card Hub
- 25. 7 Application 6 Presentation 5 Session 4 Transport 3 Network 2 Data Link 1 Physical Host layers:Host layers: Provide accurate data delivery between computers Media layers:Media layers: Control physical delivery of messages over the network } }End to End Services Network Applications Routing Data Transmission
- 26. Layer Functions 7 Application 6 Presentation 5 Session Transport4 Network3 Data Link2 Physical1 Inter-host communicationInter-host communication Network services to applicationsNetwork services to applications Data representationData representation End-to-end connection reliabilityEnd-to-end connection reliability Addresses and best pathAddresses and best path Access to mediaAccess to media Binary transmissionBinary transmission • Wires, connectors, voltages,Wires, connectors, voltages, data ratesdata rates
- 27. Service and Protocol Data Unit 07/11/17
- 28. OSI Reference model • The Open Systems Interconnection Reference Model, the OSI model was developed by the ISO (International Standards Organization) and released in 1984. • The OSI model, as it is called for short, defines the rules, mechanisms, formats, and protocols used to guide how data flows from one device to another. 07/11/17
- 29. 07/11/17
- 30. 07/11/17
- 31. Physical Layers • The Physical layer of the OSI model defines the electrical and mechanical specifications used in networking, including transmission distances, the various types of media available, and electrical issues. 07/11/17
- 32. The Data Link Layer • Physical addressing • Network topology • Error notification • Access to the physical medium • Flow control 07/11/17
- 33. The Network Layer • Message addressing • Path determination between source and destination nodes on different networks • Routing messages between networks • Controlling congestion on the subnet • Translating logical addresses into physical addresses 07/11/17
- 34. • When the message (which moves down through the seven OSI layers on Johns computer before its sent out on the local network in binary form) arrives at Router 1, it moves up from the Physical layer to the Data Link layer to the Network layer. At Layer 3, its determined that the message is not on a network attached to Router 1 and the message is sent down through the Data Link layer to the Physical layer07/11/17
- 35. The Transport Layer • Segment and assemble upper−layer applications • Transport segments from one host to another host • Establish and manage end−to−end operations • Error recovery 07/11/17
- 36. The Session Layer • A session is a series of related connection−oriented transmissions between network nodes. • Session Layer, establishes, manages, and terminates sessions between applications. • The session layer provides a name space that is used to tie together the potentially different transport streams that are part of a single application. • Session layer is its role in deciding whether a communications session uses a simplex, half−duplex, or full−duplex transmission mode. 07/11/17
- 37. Presentation Layers • Data encryption • Data compression • Data formatting • Data conversion 07/11/17
- 38. The Application Layer Application layer defines the communication services used by the users applications to transmit data over the network. FTP (File Transfer Protocol) E−mail clients Web browsers Telnet SNMP (Simple Network Management Protocol) BBS (bulletin board system) servers EDI (Electronic Data Interchange) and other transaction services 07/11/17
- 40. OSI vs TCP Reference Models OSI introduced concept of services, interface, protocols. These were force-fitted to TCP later ⇒ It is not easy to replace protocols in TCP. In OSI, reference model was done before protocols. In TCP, protocols were done before the model OSI: Standardize first, build later TCP: Build first, standardize later OSI took too long to standardize. TCP/IP was already in wide use by the time. OSI became too complex. TCP/IP is not general. Ad hoc. 07/11/17
- 42. Overview Access Network Electromagnetic Spectrum Transmission Media: Twisted Pair, Coax, fiber, wireless Unshielded Twisted Pair (UTP) categories Reflection and Refraction Antennas: Isotropic, directional, omni-directional Terrestrial and Satellite Microwave 07/11/17
- 43. Access Network Physical link that connect an end system to its edge router. Closely tied to physical media. 07/11/17
- 44. Access Network(contd.) Access networks can be loosely divided into three categories: residential access networks (using modem) Institutional access networks (using LAN) Mobile access networks (using CDPD) 07/11/17
- 45. • Guided: Twisted Pair Coaxial cable Optical fiber • Unguided: Microwave Satellite Wireless 07/11/17 Transmission Media
- 46. • Twists decrease the cross-talk • Neighboring pairs have different twist length • Most of telephone and network wiring in homes and offices is TP. • Speed increases the distance reduces Twisted Pair (TP)
- 47. • Unshielded Twisted Pair (UTP) Ordinary telephone wire Cheap, Flexible Easiest to install No shielding Suffers from external EM interference Used in Telephone and Ethernet • Shielded Twisted Pair (STP) Metal braid or sheathing that reduces interference More expensive Harder to handle (thick, heavy) Used in token rings 07/11/17 Unshielded and Shielded TP
- 48. • Cat 3 Up to 16MHz Voice grade found in most offices Twist length of 7.5 cm to 10 cm • Cat 4 Up to 20 MHz. Not used much in practice. • Cat 5 Up to 100MHz Used in 10 Mbps and 100 Mbps Ethernet Twist length 0.6 cm to 0.85 cm • Cat 5E (Enhanced), Cat 6, Cat 707/11/17 UTP Categories
- 49. • Higher bandwidth than UTP. Up to 500 MHz. • Used in cable TV • Categorized in RG-59, RG-58, RG-11 Coaxial Cable
- 50. • Unshielded twisted-pair (UTP) vs STP • Single mode and multimode optical fiber • Optical communication wavelengths • Isotropic vs omni directional vs directional antennas • Parabolic antenna for microwave • Ground wave, sky wave, line of sight 07/11/17 Summary
Editor's Notes
- You may hear the word topology used with respect to networks. “Topology” refers to the physical arrangement of network components and media within an enterprise networking structure. There are four primary kinds of LAN topologies: bus, tree, star, and ring.
- Bus topology is A linear LAN architecture in which transmissions from network components propagate the length of the medium and are received by all other components. The bus portion is the common physical signal path composed of wires or other media across which signals can be sent from one part of a network to another. Sometimes called a highway. Ethernet/IEEE 802.3 networks commonly implement a bus topology Tree topology is Similar to bus topology, except that tree networks can contain branches with multiple nodes. As in bus topology, transmissions from one component propagate the length of the medium and are received by all other components. The disadvantage of bus topology is that if the connection to any one user is broken, the entire network goes down, disrupting communication between all users. Because of this problem, bus topology is rarely used today. The advantage of bus topology is that it requires less cabling (therefore, lower cost) than star topology.
- Star topology is a LAN topology in which endpoints on a network are connected to a common central switch or hub by point-to-point links. Logical bus and ring topologies re often implemented physically in a star topology. The benefit of star topology is that even if the connection to any one user is broken, the network stays functioning, and communication between the remaining users is not disrupted. The disadvantage of star topology is that it requires more cabling (therefore, higher cost) than bus topology. Star topology may be thought of as a bus in a box.
- Ring topology consists of a series of repeaters connected to one another by unidirectional transmission links to form a single closed loop. Each station on the network connects to the network at a repeater. While logically a ring, ring topologies are most often organized in a closed-loop star. A ring topology that is organized as a star implements a unidirectional closed-loop star, instead of point-to-point links. One example of a ring topology is Token Ring. Redundancy is used to avoid collapse of the entire ring in the event that a connection between two components fails.
- Let’s put this in some context. You are already familiar with different networking devices such as hubs, switches, and routers. Each of these devices operate at a different level of the OSI Model. NIC cards receive information from upper level applications and properly package data for transmission on to the network media. Essentially, NIC cards live at the lower four layers of the OSI Model. Hubs, whether Ethernet, or FDDI, live at the physical layer. They are only concerned with passing bits from one station to other connected stations on the network. They do not filter any traffic. Bridges and switches on the other hand, will filter traffic and build bridging and switching tables in order to keep track of what device is connected to what port. Routers, or the technology of routing, lives at layer 3. These are the layers people are referring to when they speak of “layer 2” or “layer 3” devices. Let’s take a closer look at the model.
- The lower three layers – Network, Data Link and Physical -- are called the media layers. The media layers are responsible for seeing that the information does indeed arrive at the destination for which it was intended.
- The physical layer is concerned with binary transmission. It defines the electrical, mechanical, procedural, and functional specifications for activating, maintaining, and deactivating the physical link between end systems. Such characteristics as voltage levels, physical data rates, and physical connectors are defined by physical layer specifications. Now you know the role of all 7 layers of the OSI model.