Lan wan


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Lan wan

  2. 2. NETWORK  Set of devices connected by communication links.  No specific taxonomy available in which all computer networks fit, still two are of vital importance: Network Technologies Transmission Technology Geographical Span 2
  3. 3. Classification on transmission technology Point-to-point Network Broadcast Network 3
  4. 4. Network topology based on area Bus topology: Star topology: Ring Topology : Mesh topology: 4
  5. 5. Categories of Network  LAN -Privately owned and links the devices in a single office, building or campus.  MAN -Designed to extend over an entire city either by cable television network or connecting many LANs into a larger network.  WAN -Provides long-distance transmission of data, voice, image etc. over large geographic outline may be country or continent or the world. 5
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  7. 7. Components of LAN  A Local Area Network, LAN is a combination of hardware and software.  The physical component of the network system is hardware. The invisible part, that is programs enabling the network to function properly is the software.  Ethernet is the most dominant LAN in the market. 7
  8. 8. LAN Protocol Architecture  Lower layers of OSI model  IEEE 802 reference model, is a standardized protocol architecture for LANs, which describes:    Physical layer. Logical link control (LLC) sub-layer, Media access control (MAC) sub-layer. Data Link Layer 8
  9. 9. OSI Model • Provides for reliable transfer of IEEE 802 Reference Model information across the physical link • Sends blocks (frames) with necessary synchronization • Error control, flow control Application Presentation Session Transport Network Data Link Physical IEEE 802 committee developed, revises, and extends standards Use a three-layer protocol hierarchy: physical, medium access control (MAC), and logical link control (LLC) • Concerned with transmission of bit stream • Deal with mechanical, electrical functionality • Procedural characteristics to 9 access physical medium
  10. 10. ETHERNET  Most widely used data communication standard  Physical Medium – Carry signal between computers.  MAC rules embedded in each interface that allow multiple computers to access shared channel.  Ethernet frame of standardized set of bits used to carry data over the system.  Uses Star topology and 1-persistent CSMA/CD 10 access method.
  11. 11. Logical Link Control  Acts as interface between MAC and upper layer.  Accountable for flow control.  Manages error control and error detection.  Independent of topology and medium.  Specifies method of addressing whether unicast multicast or broadcast. 11
  12. 12. MAC Sublayer Governs the operation of access method and frames data from upper layer and passes them for encoding. Access method is 1-persistent CSMA/CD. Frame format 12
  13. 13. Physical Layer  Encoding/decoding of signals mostly using Manchester coding.  Bit transmission/reception  Specification of the transmission medium.  Preamble generation/removal  Transmission medium and topology 13
  14. 14. Data Transfer through Ethernet LAN Twisted pair or fiber optics with RJ-45 plug or sockets. Data rate range from 100Mbits/s to 1000Mbits/s To network multiple devices, switch is required where devices are connected to it using regular network cable.  Registers MAC address of each devices connected to it. When switch receives data, it forwards it only to the port that is connected to the device with appropriate destination MAC address.    14
  15. 15. Token Ring Network        Originally developed by IBM in 1970’s Still IBM’s primary LAN technology In cases of heavy traffic, the token ring network has higher throughput than Ethernet due to the deterministic (nonrandom) nature of the medium access Is used in applications in which delay when sending data must be predictable Is a robust network i.e. it is fault tolerant through fault management mechanisms Can support data rates of around 16 Mbps Typically uses twisted pair 15
  16. 16. FDDI (Fiber Distributed Data Interface)  FDDI is a standard developed by the American National Standards Institute (ANSI) for transmitting data on optical fibers  Supports transmission rates of up to 200 Mbps  Uses a dual ring  First ring used to carry data at 100 Mbps. Second ring used for primary backup in case first ring fails  If no backup is needed, second ring can also carry data, increasing the data rate up to 200 Mbps  Supports up to 1000 nodes 16
  17. 17. Wide Area Network  Contains collection of machines called hosts running user program and the host are connected by subnet which carries message from host to host.  Host owned by customers and subnet by ISP.  Subnet consists of transmission lines and switching element.  Switching computers are called routers 17
  18. 18. Wide Area Network (Contd.)  Packets sent from receiver to sender may be stored at intermediate router till the required output line is busy.  This principle is known as “Store-n-Forward” which is implemented by almost all WAN except using Satellite.  Sender cuts the data into packets bearing a number and injected into network one at a time and at the receiver they are reassembled into original message. 18
  19. 19. WAN TECHNOLOGY  Devices on subscriber premises are called Customer Premises Equipment owned by the subscriber.  Copper or fiber cable connects CPE to Central Office (CO) which is known as local loop. 19
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  21. 21. WAN Link Options 21
  22. 22. Circuit Switched  When a subscriber makes a telephone call, the dialed number is used to set switches in the exchanges along the route of the call so that there is a continuous circuit from the originating caller to that of the called party where the internal path is shared by a number of conversations.  Time division multiplexing (TDM) is used to give each conversation a share of the connection in turn. 22
  23. 23. PACKET SWITCHING  An alternative is to allocate the capacity to the traffic only when it is needed. Share the available capacity between many users  Huge data converted into packets which passes from exchange to exchange through network.  Allows same data path to be shared between various users in the network. 23
  24. 24. Leased Lines  A point-to-point link provides a pre-established WAN communications path from the customer premises through the provider network to a remote destination.  Point-to-point lines are usually leased from a carrier and are called leased lines.  Leased lines provide direct point-to-point connections between LANs and connect individual branches to a packet-switched network. 24
  25. 25. WAN Considerations  Many WANs are connected to the Internet to provide alternative for inter-branch connections.  Since the Internet probably exists everywhere that the enterprise has LANs, there are two principal ways that this traffic can be carried.  Each LAN can have a connection to its local ISP, or there can be a single connection from one of the core routers to an ISP.  The advantage is that traffic is carried on the Internet rather than on the enterprise network, possibly leading to smaller WAN links. 25
  26. 26. Thank You!! 26