Underlying Technologies ppt - Csmaster

Chapter 3UnderlyingTechnologyTCP/IP Protocol Suite 1Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

OBJECTIVES: To briefly discuss the technology of dominant wired LANs,Ethernet, including traditional, fast, gigabit, and ten-gigabitEthernet. To briefly discuss the technology of wireless WANs, includingIEEE 802.11 LANs, and Bluetooth. To briefly discuss the technology of point-to-point WANsincluding 56K modems, DSL, cable modem, T-lines, and SONET. To briefly discuss the technology of switched WANs includingX.25, Frame Relay, and ATM. To discuss the need and use of connecting devices such asrepeaters (hubs), bridges (two-layer switches), and routers(three-layer switches).TCP/IP Protocol Suite 2

ChapterOutline3.1 Wired Local Area Network3.2 Wireless LANs3.3 Point-to-Point WANs3.4 Switched WANs3.5 Connecting DevicesTCP/IP Protocol Suite 3

3-1 WIRED LOCAL AREA NETWORKSA local area network (LAN) is a computer network that isdesigned for a limited geographic area such as abuilding or a campus. Although a LAN can be used asan isolated network to connect computers in anorganization for the sole purpose of sharing resources,most LANs today are also linked to a wide area network(WAN) or the Internet.The LAN market has seen several technologiessuch as Ethernet, token ring, token bus, FDDI, and ATMLAN, but Ethernet is by far the dominant technology.TCP/IP Protocol Suite 4

Topics Discussed in the SectionIEEE StandardsFrame FormatAddressingEthernet EvolutionStandard EthernetFast EthernetGigabit EthernetTen-Gigabit EthernetTCP/IP Protocol Suite 5

Figure 3.1 IEEE standard for LANsTCP/IP Protocol Suite 6

Figure 3.2 Ethernet FrameTCP/IP Protocol Suite 7

Figure 3.3 Maximum and minimum lengthsTCP/IP Protocol Suite 8

NoteThe least significant bit of the first bytedefines the type of address.If the bit is 0, the address is unicast;otherwise, it is multicast.TCP/IP Protocol Suite 13

Figure 3.6 Ethernet evolution through four generationsTCP/IP Protocol Suite 16

Figure 3.7 Space/time model of a collision in CSMAB startsat time t 1C startsat time t 2A BC DArea whereA’s signal existsArea whereboth signals existArea whereB’s signal existsT i m eT i m eTCP/IP Protocol Suite 17

Figure 3.8 Collision of the first bit in CSMA/CDTCP/IP Protocol Suite 18

Example 3.3In the standard Ethernet, if the maximum propagation time is25.6 μs, what is the minimum size of the frame?SolutionThe frame transmission time is T fr = 2 × T p = 51.2 μs. Thismeans, in the worst case, a station needs to transmit for aperiod of 51.2 μs to detect the collision. The minimum size ofthe frame is 10 Mbps × 51.2 μs = 512 bits or 64 bytes. This isactually the minimum size of the frame for Standard Ethernet,as we discussed before.TCP/IP Protocol Suite 19

Figure 3.9 CSMA/CD flow diagramTCP/IP Protocol Suite 20

TCP/IP Protocol Suite 21

Figure 3.10 Standard Ethernet implementationTCP/IP Protocol Suite 22

TCP/IP Protocol Suite 23

Figure 3.11 Fast Ethernet implementationTCP/IP Protocol Suite 24

TCP/IP Protocol Suite 25

NoteIn the full-duplex mode of GigabitEthernet, there is no collision;the maximum length of the cable isdetermined by the signal attenuationin the cable.TCP/IP Protocol Suite 26

Figure 3.12 Gigabit Ethernet implementationTCP/IP Protocol Suite 27

TCP/IP Protocol Suite 28

3-2 WIRELESS LANSWireless communication is one of the fastestgrowing technologies. The demand for connectingdevices without the use of cables is increasingeverywhere. Wireless LANs can be found on collegecampuses, in office buildings, and in many publicareas. In this section, we concentrate on twowireless technologies for LANs: IEEE 802.11wireless LANs, sometimes called wireless Ethernet,and Bluetooth, a technology for small wireless LANs.TCP/IP Protocol Suite 29

Topics Discussed in the SectionIEEE 802.1MAC SublayerAddressing MechanismBluetoothTCP/IP Protocol Suite 30

Figure 3.13 Basic service sets (BSSs)TCP/IP Protocol Suite 31

Figure 3.14 Extended service sets (ESSs)TCP/IP Protocol Suite 32

Figure 3.15 CSMA/CA flow diagramTCP/IP Protocol Suite 33

Figure 3.16 CSMA/CA and NAVSourceDestinationAll other stations• • •DIFSSIFS31RTSCTS 2DataSIFSNAV(No carrier sensing)ACK 4SIFSTime TimeTime TimeTCP/IP Protocol Suite 34

Figure 3.17 Frame formatTCP/IP Protocol Suite 35

TCP/IP Protocol Suite 36

Figure 3.18 Control framesTCP/IP Protocol Suite 37

TCP/IP Protocol Suite 38

TCP/IP Protocol Suite 39

Figure 3.19 Hidden station problemTCP/IP Protocol Suite 40

NoteThe CTS frame in CSMA/CA handshakecan prevent collision from a hiddenstation.TCP/IP Protocol Suite 41

Figure 3.20 Use of handshaking to prevent hidden station problemBACRTSCTSCTSTime Time TimeTCP/IP Protocol Suite 42

Figure 3.21 Exposed station problemTCP/IP Protocol Suite 43

Figure 3.22 Use of handshaking in exposed station problemRTSCTSDataRTSRTSDataRTSCTSCollisionhereTCP/IP Protocol Suite 44

Figure 3.23 PiconetTCP/IP Protocol Suite 45

Figure 3.24 ScatternetTCP/IP Protocol Suite 46

Figure 3.25 Frame format types72 bits 54 bits 0 to N bitsAccess code Header DataTCP/IP Protocol Suite 47

3-3 POINT-TO-POINT WANSA second type of network we encounter in theInternet is the point-to-point wide area network. Apoint-to-point WAN connects two remote devicesusing a line available from a public network such asa telephone network. We discuss traditional modemtechnology, DSL line, cable modem, T-lines, andSONET.TCP/IP Protocol Suite 48

Topics Discussed in the Section65K ModemsDSL TechnologyCable ModemT Lines SONETPPPTCP/IP Protocol Suite 49

Figure 3.26 56K modemUploading,quantization noiseDownloading,no quantization noiseTCP/IP Protocol Suite 50

NoteADSL is an asymmetric communicationtechnology designed for residentialusers; it is not suitable for businesses.TCP/IP Protocol Suite 51

Figure 3.27 Bandwidth divisionTCP/IP Protocol Suite 52

Figure 3.28 ADSL and DSLAMTCP/IP Protocol Suite 53

Figure 3.29 Cable bandwidthTCP/IP Protocol Suite 54

Figure 3.30 Cable modem configurationTCP/IP Protocol Suite 55

TCP/IP Protocol Suite 56

TCP/IP Protocol Suite 57

Figure 3.31 PPP frameTCP/IP Protocol Suite 58

3-4 SWITCHED WANSThe backbone networks in the Internet can beswitched WANs. A switched WAN is a wide areanetwork that covers a large area (a state or acountry) and provides access at several points to theusers. Inside the network, there is a mesh of pointto-pointnetworks that connects switches. Theswitches, multiple port connectors, allow theconnection of several inputs and outputs.Switched WAN technology differs from LANtechnology in many ways.TCP/IP Protocol Suite 59

Topics Discussed in the SectionX.25Frame RelayATMTCP/IP Protocol Suite 60

NoteA cell network uses the cell as the basicunit of data exchange.A cell is defined as a small, fixed-sizeblock of information.TCP/IP Protocol Suite 61

Figure 3.32 ATM multiplexingA3A2A1B2B1C3B2A3C2B1A2C1A1C3C2C1TCP/IP Protocol Suite 62

Figure 3.33 Architecture of an ATM networkTCP/IP Protocol Suite 63

Figure 3.34 Virtual circuitTCP/IP Protocol Suite 64

NoteA virtual connection is defined by a pairof numbers: the VPI and the VCI.TCP/IP Protocol Suite 65

Figure 3.35 ATM layersTCP/IP Protocol Suite 66

Figure 3.36 Use of the layersTCP/IP Protocol Suite 67

NoteThe IP protocol uses the AAL5 sublayer.TCP/IP Protocol Suite 68

Figure 3.37 AAL5TCP/IP Protocol Suite 69

Figure 3.38 ATM layerTCP/IP Protocol Suite 70

Figure 3.39 An ATM cellTCP/IP Protocol Suite 71

3-5 CONNECTING DEVICESLANs or WANs do not normally operate in isolation.They are connected to one another or to theInternet. To connect LANs and WANs together weuse connecting devices. Connecting devices canoperate in different layers of the Internet model. Wediscuss three kinds of connecting devices: repeaters(or hubs), bridges (or two-layer switches), androuters (or three-layer switches).TCP/IP Protocol Suite 72

Topics Discussed in the SectionRepeatersBridgesRoutersTCP/IP Protocol Suite 73

Figure 3.40 Connecting devicesTCP/IP Protocol Suite 74

Figure 3.41 Repeater or hubSentMaintainedTCP/IP Protocol Suite 75

NoteA repeater forwards every bit; it has nofiltering capability.TCP/IP Protocol Suite 76

NoteA bridge has a table used in filteringdecisions.TCP/IP Protocol Suite 77

NoteA bridge does not change the physical(MAC) addresses in a frame.TCP/IP Protocol Suite 78

Figure 3.42 BridgeBridge tableAddress Port71:2B:13:45:61:41 171:2B:13:45:61:42 264:2B:13:45:61:12 364:2B:13:45:61:13 4TCP/IP Protocol Suite 79

Figure 3.43 Learning bridgeAddressa. OriginalPortAddress Port71:2B:13:45:61:41 164:2B:13:45:61:13 4c. After D sends a frame to BAddress Port71:2B:13:45:61:41 164:2B:13:45:61:13 471:2B:13:45:61:42 2d. After B sends a frame to AAddress Port71:2B:13:45:61:41 164:2B:13:45:61:1371:2B:13:45:61:424264:2B:13:45:61:12 3e. After C sends a frame to DMMMMTCP/IP Protocol Suite 80

NoteA router is a three-layer (physical, datalink, and network) device.TCP/IP Protocol Suite 81

NoteA repeater or a bridge connectssegments of a LAN.A router connects independent LANs orWANs to create an internetwork(internet).TCP/IP Protocol Suite 82

Figure 3.44 Routing exampleTCP/IP Protocol Suite 83

NoteA router changes the physicaladdresses in a packet.TCP/IP Protocol Suite 84