LAN SystemsOverviewLAN TopologiesMedia Access Control (MAC)Slide 5CSMA/CDIEEE 802.3 CSMA/CDCSMA/CD OperationOriginal Ethernet Configuration10BASE-TEthernet StandardsEthernet Standards (Cont)Slide 13CSMA/CD PerformanceCSMA/CD Performance (Cont)Distance-B/W PrincipleEthernet vs Fast EthernetFull-Duplex EthernetIEEE 802 Address FormatToken RingToken Ring Priority RulesHomeworkPriority StackToken Ring PerformancePerformance (Continued)Performance (continued)FDDIDual-Ring of Trees TopologyTimed Token AccessExampleTRTPrioritiesTP-PMDSummarySlide 35Raj JainThe Ohio State University1LAN SystemsLAN SystemsRaj JainProfessor of CIS The Ohio State UniversityColumbus, OH [email protected] presentation is available on-line athttp://www.cse.ohio-state.edu/~jain/cis677-98/Raj JainThe Ohio State University2OverviewOverviewIEEE 802.3: Ethernet and fast EthernetIEEE 802.5: Token ring Fiber Distributed Data Interface (FDDI)Raj JainThe Ohio State University3(d) StarCentral hub, sw itch, or repeater(a) BusTerminating resistanceTapStationRepeaterFlow of data(c) Ring(b) TreeHeadendLAN TopologiesLAN TopologiesFig 12.4Raj JainThe Ohio State University4Media Access Control (MAC)Media Access Control (MAC)Bus Topology Ring TopologyToken Passing IEEE 802.4Token busIEEE 802.5Token RingSlotted Access IEEE 802.6DQDBCambridgeRingContention IEEE 802.3CSMACDSlottedRingRaj JainThe Ohio State University5(a) Multiple Access(b) Carrier-Sense Multiple Access with Collision DetectionRaj JainThe Ohio State University6CSMA/CDCSMA/CDAloha at Univ of Hawaii: Transmit whenever you likeWorst case utilization = 1/(2e) =18%Slotted Aloha: Fixed size transmission slotsWorst case utilization = 1/e = 37%CSMA: Carrier Sense Multiple Access Listen before you transmitp-Persistent CSMA: If idle, transmit with probability p. Delay by one time unit with probability 1-pCSMA/CD: CSMA with Collision DetectionListen while transmitting. Stop if you hear someone elseRaj JainThe Ohio State University7IEEE 802.3 CSMA/CDIEEE 802.3 CSMA/CDIf the medium is idle, transmit (1-persistent).If the medium is busy, wait until idle and then transmit immediately.If a collision is detected while transmitting,Transmit a jam signal for one slot (= 51.2 s = 64 byte times)Wait for a random time and reattempt (up to 16 times)Random time = Uniform[0,2min(k,10)-1] slotsCollision detected by monitoring the voltageHigh voltage  two or more transmitters  Collision  Length of the cable is limited to 2 kmRaj JainThe Ohio State University8CSMA/CD OperationCSMA/CD OperationCollision window = 2 X One-way Propagation delay = 51.2 sFig 13.1One way delay = 25.6 sMax Distance<2.5 kmRaj JainThe Ohio State University9Original Ethernet ConfigurationOriginal Ethernet ConfigurationSegmentRepeaterStationFig 12.9SegmentRaj JainThe Ohio State University1010BASE-T10BASE-TCollision detected by the hub.Activity on two or more channels  CollisionCollision presence (CP) transmitted by hub to all stationsCollision window = 2× One-way delay between farthest stationsRRRRRRRaj JainThe Ohio State University11Ethernet StandardsEthernet Standards10BASE5: 10 Mb/s over coaxial cable (ThickWire)10BROAD36: 10 Mb/s over broadband cable, 3600 m max segments1BASE5: 1 Mb/s over 2 pairs of UTP10BASE2: 10 Mb/s over thin RG58 coaxial cable (ThinWire), 185 m max segments10BASE-T: 10 Mb/s over 2 pairs of UTP10BASE-FL: 10 Mb/s fiber optic point-to-point link10BASE-FB: 10 Mb/s fiber optic backbone (between repeaters). Also, known as synchronous Ethernet.Raj JainThe Ohio State University12Ethernet Standards (Cont)Ethernet Standards (Cont)10BASE-FP: 10 Mb/s fiber optic passive star + segments10BASE-F: 10BASE-FL, 10BASE-FB, or 10BASE-FP100BASE-T4: 100 Mb/s over 4 pairs of CAT-3, 4, 5 UTP100BASE-TX: 100 Mb/s over 2 pairs of CAT-5 UTP or STP100BASE-FX: 100 Mbps CSMA/CD over 2 optical fiberRaj JainThe Ohio State University13100BASE-T100BASE-T100BASE-T4100BASE-T4100BASE-X100BASE-X100BASE-TX100BASE-TX100BASE-FX100BASE-FXEthernet Standards (Cont)Ethernet Standards (Cont)100BASE-X: 100BASE-TX or 100BASE-FX100BASE-T: 100BASE-T4, 100BASE-TX, or 100BASE-FX1000BASE-T: 1 Gbps (Gigabit Ethernet)Raj JainThe Ohio State University14CSMA/CD PerformanceCSMA/CD Performancea = Propagation delay/Frame timeU = Frame Time/(Propagation delay+Frame Time) = 1/(1+a)Fig 13.26t=0t=at=at=1+at=0t=at=at=1+aRaj JainThe Ohio State University15CSMA/CD Performance (Cont)CSMA/CD Performance (Cont)U=1/[1+2a(1-A)/A], where A = (1-1/N)N-1  e-1Worst case U = 1/(1+3.44a) with N= Fig 13.28Raj JainThe Ohio State University16Distance-B/W PrincipleDistance-B/W PrincipleEfficiency = Max throughput/Media bandwidthEfficiency is a decreasing function of  = Propagation delay /Transmission time = (Distance/Speed of light)/(Transmission size/Bits/sec)= Distance×Bits/sec/(Speed of light)(Transmission size)Bit rate-distance-transmission size tradeoff. 100 Mb/s  Change distance or frame sizeRaj JainThe Ohio State University17CableEthernetCSMA/CDEthernet vs Fast EthernetEthernet vs Fast EthernetFast EthernetSpeed 10 Mbps 100 MbpsMAC CSMA/CDNetwork diameter 2.5 km 205 mTopology Bus, star StarCoax, UTP, Fiber UTP, FiberStandard 802.3 802.3uCost X 2XRRRRRaj JainThe Ohio State University18Full-Duplex EthernetFull-Duplex EthernetUses point-to-point links between TWO nodesFull-duplex bi-directional transmissionTransmit any timeNot yet standardized in IEEE 802Many vendors are shipping switch/bridge/NICs with full duplexNo collisions  50+ Km on fiber.Between servers and switches or between switchesRaj JainThe Ohio State University19IEEE 802 Address FormatIEEE 802 Address FormatMulticast = “To all bridges on this LAN”Broadcast = “To all stations” = 111111....111 = FF:FF:FF:FF:FF:FF48-bit:1000 0000 : 0000 0001 : 0100 0011 : 0000 0000 : 1000 0000 : 0000 1100 = 80:01:43:00:80:0CIndividual/GroupUniversal/Local24 bits assigned by OUI Owner1 1 2224Organizationally Unique Identifier (OUI)Raj JainThe Ohio State University20Token RingToken RingFig 13.5Delayed token release vs Immediate token release4 Mb/s16 Mb/sRaj JainThe Ohio State University21Token Ring Priority RulesToken Ring Priority RulesReceived Priority = Pr  This token/frame’s priorityReceived reservation = Rr  Someone on the ring wants to transmit at RrTo transmit a message of priority Pm,