Bài giảng Network - Chapter 05

Chapter Overview EthernetToken RingFDDIWireless Networking 1Ethernet Standards Ethernet is the most popular local area network (LAN) protocol operating at the data-link layer.There are two sets of Ethernet standards:DIX EthernetInstitute of Electrical and Electronic Engineers (IEEE) 802.3 2DIX Ethernet Standards DIX Ethernet. Also known as thick Ethernet, ThickNet, or 10Base5DIX Ethernet II. Retains 10Base5 and adds 10Base2 (thin Ethernet) 3IEEE 802.3 Standards IEEE 802.3. 10Base5, 10Base2, and 10Base-TIEEE 802.3u. Fast EthernetIEEE 802.3z and IEEE 802.3ab. Gigabit Ethernet4DIX Ethernet/IEEE 802.3 Components Physical layer specificationsFrame formatCSMA/CD MAC mechanism 5Standard 10-Mbps Ethernet Specifications DesignationCable TypeTopologyMaximum Length10Base5RG-8 coaxialBus500 meters10Base2RG-58 coaxialBus185 meters10Base-TCategory 3 UTPStar100 metersFiber Optic Inter-Repeater Link (FOIRL)Multimode fiber opticStar1,000 meters10Base-FMultimode fiber opticStar500–2,000 meters6Fast Ethernet (100 Mbps) Specifications DesignationCable TypeTopologyMaximum Length100Base-TX Category 5 UTPStar100 meters100Base-T4Category 3 UTPStar100 meters100Base-FXMultimode fiber opticStar412 meters7Gigabit Ethernet (1,000 Mbps) Specifications DesignationCable TypeTopologyMaximum Length1000Base-TCategory 5 or 5E UTPStar100 meters1000Base-LXVarious multimode fiber opticStar550–5,000 meters1000Base-SXVarious multimode fiber opticStar220–500 meters1000Base-LHSinglemode fiber opticStar10 kilometers1000Base-ZXSinglemode fiber opticStar100 kilometers1000Base-CX150-ohm copperStar25 meters8Coaxial Ethernet Standards 10Base5 (thick Ethernet)10Base2 (thin Ethernet) 9Coaxial Network Characteristics Runs at 10 MbpsUses the bus topologyUses mixing segments 10Mixing Segments11UTP Ethernet Standards 10Base-T100Base-TX (Fast Ethernet)100Base-T4 (Fast Ethernet)1000Base-T (Gigabit Ethernet) 12UTP Network Characteristics Runs at various speeds up to 1,000 MbpsUses the star topologyRequires a hubUses link segments 13Link Segments 14Fiber Optic Ethernet Fiber Optic Inter-Repeater Link (FOIRL)IEEE 802.3 fiber optic standards:10Base-FL10Base-FB10Base-FP100Base-FXGigabit Ethernet standards 15The 5-4-3 Rule A standard network can have no more than FIVE segments, connected by FOUR repeaters, of which no more than THREE segments can be mixing segments. 16A Coaxial 5-4-3 Network 17A UTP 5-4-3 Network18Fast Ethernet Hub Types ClassFunctionIConnects different cable segment typesIIConnects identical cable segment types19Fast Ethernet Cabling Guidelines Hub TypeMaximum Number of HubsMaximum Total Cable Length (UTP)Maximum Total Cable Length (Fiber Optic)Class I1200 meters272 metersClass II2205 meters228 meters20The Ethernet Frame Format21Protocol Identification DIX Ethernet frames use the Ethertype field.IEEE 802.3 frames use the Logical Link Control (LLC) and Subnetwork Access Protocol (SNAP) subheaders.22Media Access Control (MAC) Is the mechanism that enables multiple computers to use the same network medium without conflicting 23CSMA/CD Phases PhaseDescriptionCarrier senseA computer listens to the network before transmitting.Multiple accessWhen the network is clear, the computer transmits the packet.Collision detectionThe computer checks for signs of a collision. If one occurs, it retransmits the packet.24Collisions Collisions are also called signal quality errors.They are normal on Ethernet networks.The frequency of collisions increases as network traffic increases.Late collisions are a sign of a serious problem. 25Token Ring Cable Types IBM Type 1. Proprietary shielded twisted pair (STP)IBM Type 3. Standard Category 5 unshielded twisted pair (UTP) 26IBM Type 1 Cable27Token Passing A token frame circulates continuously around the network.Only the computer holding the token can transmit data.The transmitting system is responsible for removing the data from the ring. 28Token Ring Frame Types Data frameToken frameCommand frameAbort delimiter frame 29The Data Frame Format30The Token Frame Format31Fiber Distributed Data Interface (FDDI) Characteristics First commercial 100-Mbps fiber optic protocolUses the token passing MAC mechanismSupports both singlemode and multimode cable 32FDDI Topologies Double ring Logical ringDual ring of trees 33Dual Ring of Trees34The FDDI Data Frame35IEEE 802.11 Standards IEEE 802.11a. Speeds of 1 to 2 MbpsIEEE 802.11b. Speeds of 5.5 to 11 Mbps 36IEEE 802.11 Topologies Ad hoc. Wireless computers communicating with each otherInfrastructure. Wireless computers using an access point to communicate with a cabled network 37CSMA/CA Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) is a variation of CSMA/CD.It uses packet acknowledgment messages instead of collision detection. 38Chapter Summary Ethernet Supports multiple cable types and speedsUses the CSMA/CD MAC mechanism to detect collisionsToken RingUses a logical ring topology Uses the token passing MAC mechanismFDDIUses a double ring or star topologyUses the token passing MAC mechanismWireless NetworkingRuns at speeds up to 11 MbpsUses the CSMA/CA MAC mechanism 39