1. Ethernet Technologies Khondaker Abdullah-Al-Mamun Lecturer, CSE Instructor, CNAP AUST

2. Ethernet Technologies

3. Ethernet 1-2-3  Originated from a project by Digital, Intel, and Xerox  The most popular LAN standard in the world Connects 80% of LAN devices  The IEEE (Institute for Electrical and Electronics Engineers) 802.3 CSMA/CD (Carrier Sensing Multiple Access with Collision Detection) committee now forms and administers Ethernet standards  The unit of data traveling on Ethernet is called frame (many variations in structure)  Ethernet and CSMA/CD can be used interchangeably  Implemented on NICs (Network Interface Cards)  Ethernet technology is at the physical and data link layers

4. Overview In faster versions of Ethernet MAC addressing, CSMA/CD, and the frame format have not been changed from earlier versions of Ethernet. Other aspects of the MAC sublayer, physical layer and medium have changed. Copper based NICs capable of 10/100/1000 operation are now common. Gigabit switch and router ports are becoming the standard for wiring closets. Optical fiber to support Gigabit Ethernet is considered a standard for backbone cabling in most new installations.

5. 10 Mbps Ethernet 10BASE-5, 10BASE-2, and 10BASE-T Ethernet are considered Legacy Ethernet. The four common features of Legacy Ethernet are –timing parameters, –frame format, –transmission process, and –a basic design rule.

6. Parameters for 10 Mbps Ethernet Operation

7. Parameters for 10 Mbps Ethernet Operation (cont.) Bit Time: 1 bit time at 10 Mbps= 100 nanoseconds = 0.1 microseconds = 0.0001 seconds This means that on a 10-Mbps Ethernet network, 1 bit at the MAC sub- layer requires 100 ns to transmit.

8. Signal Quality Error (SQE) Transmission process is identical until the lower part of the OSI layer. MAC sublayer Physical layer frame bit Process SQE is a process of determining whether the collision circuitry is functional. SQE is called Heartbeat

9. SQE - Instances 1.Within 4 to 8 microseconds after a normal transmission to indicate that outbound frame was successfully transmitted. 2.Whenever there is a collision on the medium. 3.Whenever there is a improper signal on the medium. 4.Whenever a transmission has been interrupted.

10. Line Encoding 1. All 10 Mbps forms of Ethernet take octets received from the MAC sublayer and perform a process called line encoding. Line encoding describes how the bits are actually signaled on the wire. 2. The form of encoding used in 10 Mbps systems is called “Manchester.” 3. Manchester encoding relies on the direction of the edge transition in the middle of the timing window to determine the binary value for that bit period. 4. The binary bit values are indicated by the direction of change during any given bit period. The waveform voltage levels at the beginning or end of any bit period are not factors when determining binary values.

11. Timing Limits 1. The timing limits are based on parameters such as: Cable length and its propagation delay Delay of repeaters Delay of transceivers Interframe gap shrinkage Delays within the station

12. Ethernet Cabling Options  Dealing with the Physical Layer (Layer 1) Cabling specifications Topologies: (the order in which stations receive bits) Connectors  10Mbps 10Base5 10Base2 10baseT 10BaseFL  100Mbps 100BaseTX 100BaseT4 100BaseFX (multimode Fiber Optic)  Gigabit Ethernet

13. 10Base5 Ethernet

14. Characteristics of 10Base5 Ethernet  Uses a large coaxial cable  Stations are connected to the cable using a vampire tap  A transceiver or MAU (medium attachment unit) is mounted on the vampire tap  An AUI (attachment interface unit) cable runs from the transceiver to the station  Coaxial cable is installed in a bus topology (straight line) with a 50 ohm terminator. One end should be grounded  Each of the maximum 5 segments of thick coax may be up to 500 meters in length. Can have up to 100 stations, up to 500 meters  The LAN fails if there is one break in the cabling system  10BASE-5 uses Manchester encoding.  The cable is large, heavy, and difficult to install

15. Manchester Encoding

16. 10Base5 Ethernet Network Design Limit 1.Only three segments can have stations 2.Two repeated segments are used to extend the network

17. 10Base2 Ethernet

18. Characteristics of 10Base2 Ethernet  Uses thinner cable (RG58)  BNC T-connectors are used  Cabling is configured in a bus topology  Each of the cable is terminated with a 50 terminator  Up to 30 stations cab be attached  Cabling cannot exceed 185 meters (607 feet) in total length for a segment  A single cable fault causes total LAN failure  10BASE-2 also uses Manchester encoding.  Only 1 station can transmit at a time; otherwise a collision will occur.  It uses half duplex.  The maximum transmission rate is 10 Mbps.

19. 10BASE2 Network Design Limit

20. 10BaseT Ethernet

21. Characteristics of 10BaseT Ethernet 1. UTP (unshielded Twisted Pairs) cabling, category 3 or higher, is installed 2. A hub and NIC are used to connect devices 3. Has a 100-meter distance limitation 4. RJ45 connectors are used on the hubs and NICs 5. Pins 1, 2, 3, and 6 are used on the RJ45 connectors 6. If one cable breaks, only that connection is affected 7. Patch panels and wall jacks are used to facilitate moves, additions, or changes 8. 10BASE-T also uses Manchester encoding. 9. 10BASE-T uses cheaper and easier-to-install Category 3 unshielded twisted-pair (UTP) copper cable rather than coax cable. 10. Half duplex or full duplex is a configuration choice. 11. 10BASE-T carries 10 Mbps of traffic in half-duplex mode and 20 Mbps in full-duplex mode.

22. 10BASE-T Wiring and Architecture 10BASE-T links generally consist of a connection between the station and a hub or switch.

23. 10Mbps Ethernet Design: The 5-4-3 Rule 1 2 3 4 5

24. The 5-4-3 Rule (for 10Mbps Ethernet)  Ethernet hubs can be connected to each other to extend distances  Must follow the 5-4-3 rule In a worst scenario, a single collision domain can include 5 Ethernet segments between two stations (User A to User B) Of the five segments, up to three segments may be populated If the rule is violated, the CSMA/CS protocol would not work properly (too many collisions) A bridge/router/switch/gateway connection separates collision domains

25. 100-Mbps Ethernet/Fast Ethernet 1.100 Mbps Ethernet is also known as Fast Ethernet. 2.The two technologies that became important are a.100BASE-TX, which is copper UTP based, and b.100BASE-FX, which is multimode optical fiber based.

26. 100-Mbps Ethernet/Fast Ethernet  Three characteristics common to 100BASE-TX and 100BASE-FX Timing parameters Frame format Parts of the transmission process.  100BASE-TX and 100-BASE-FX both share timing parameters.  Note that one bit time in 100-Mbps Ethernet is 10nsec =.01 microseconds = 1 100-millionth of a second.

27. 100BaseTX

28. Characteristics of 100BaseTX Ethernet  Uses same media access control as 10 Mbps Ethernet  Uses same frame structures as 10 Mbps Ethernet  Requires a hub port and NIC, which must be 100BaseTX compliant  Can operate in full duplex mode in certain situations (from a switch to a server)  Requires category 5 UTP installation  Has a 100-meter distance limitation

29. 100BaseTX Ethernet (C ont.)  Fast Ethernet represents a 10-fold increase in speed over 10BASE-T.  Because of the increase in speed, extra care must be taken because the bits being sent are getting shorter in duration and occurring more frequently. These higher frequency signals are more susceptible to noise. Two separate encoding steps are used by 100-Mbps Ethernet.  The first part of the encoding uses a technique called 4B/5B,  second part of the encoding is the actual line encoding specific to copper or fiber.

30. 100BaseTX Ethernet (C ont.)  100BASE-TX uses 4B/5B encoding, which is then scrambled and converted to multi-level transmit-3 levels or MLT-3. No transition indicates that a binary 0 is present. A transition in the center of the timing window. A binary 1 is represented by a transition. Rising or falling edges indicate 1s. Very steep signal changes indicate 1s. Any noticeable horizontal line in the signal indicates a 0. 100BASE-TX carries 100 Mbps of traffic in half- duplex mode. In full-duplex mode, 100BASE-TX can exchange 200 Mbps of traffic. MLT3 Encoding

31. 100BaseFX–Ethernet Building Backbone

32. 100BaseFX Ethernet (cont.)  The timing, frame format, and transmission are all common to both versions of 100 Mbps Fast Ethernet. 100BASE-FX also uses 4B/5B encoding  A binary 1 is represented by a transition  No transition indicates a binary 0  Fiber pair with either ST or SC connectors is most commonly used.  200 Mbps transmission is possible because of the separate Transmit and Receive paths in 100BASE- FX optical fiber. NRZI Encoding

33. Fast Ethernet architecture  A Class I repeater may introduce up to 140 bit-times of latency. Any repeater that changes between one Ethernet implementation and another is a Class I repeater.  A Class II repeater may only introduce a maximum of 92 bit-times latency. Because of the reduced latency it is possible to have two Class II repeaters in series, but only if the cable between them is very short.  May not exceed 5 meters

34. Gigabit Ethernet

35. Gigabit Ethernet/1000 Mbps 1.The 1000 Mbps Ethernet or Gigabit Ethernet standards represent transmission using both fiber and copper media. 2.The 1000BASE-X standard (IEEE 802.3z) specifies a 1-Gbps full duplex over optical fiber. 3.The 1000BASE-T standard (IEEE 802.3ab) uses a media of Category 5 or higher UTP. 4.1000BASE-TX, 1000BASE-SX, and 1000BASE-LX use the same timing parameters.

36. Gigabit Ethernet  The 1000-Mbps Ethernet or Gigabit Ethernet standards represent transmission using both fiber and copper media They use a 1 nanosecond (0.000000001 seconds) or 1 billionth of a second bit time The Gigabit Ethernet frame has the same format as is used for 10 and 100-Mbps Ethernet. Depending on the implementation, Gigabit Ethernet may use different processes to convert frames to bits on the cable  Due to the increased speeds of newer standards, the shorter duration bit times require special considerations. Since the bits are introduced on the medium for a shorter duration and more often, timing is critical. High-speed transmission requires frequencies closer to copper medium bandwidth limitations. This causes the bits to be more susceptible to noise on copper media

37. Gigabit Ethernet (Cont’d)  Uses two separate encoding steps.  Data transmission is made more efficient by using codes to represent the binary bit stream.  The encoded data provides synchronization, efficient usage of bandwidth, and improved Signal-to-Noise Ratio characteristics  At the physical layer, the bit patterns from the MAC layer are converted into symbols. The symbols may also be control information such as start frame, end frame, medium idle conditions. The frame is coded into control symbols and data symbols to increase in network throughput.

38. Gigabit Ethernet (Cont’d)  Fiber-based Gigabit Ethernet (1000BASE-X) uses 8B/10B encoding which is similar to the 4B/5B concept.  This is followed by the simple Non-Return to Zero (NRZ) line encoding of light on optical fiber. This simpler encoding process is possible because the fiber medium can carry higher bandwidth signals

39. Gigabit Ethernet (Cont’d)  Cat 5e cable can reliably carry up to 125 Mbps of traffic  Getting 1000 Mbps (Gigabit) of bandwidth. The first step is to use all four pairs of wires instead of the traditional two pairs of wires.  This is done using complex circuitry to allow full duplex transmissions on the same wire pair. This provides 250 Mbps per pair. Four-wire pairs provide 1000 Mbps.  Since the information travels simultaneously across the four paths, the circuitry has to divide frames at the transmitter and reassemble them at the receiver.

40. Gigabit Ethernet (Cont’d)  The 1000BASE-T encoding with 4D-PAM5 line encoding is used on Cat 5e or better UTP  Transmission and reception of data happens in both directions on the same wire at the same time  This results in a permanent collision on the wire pairs.  These collisions result in complex voltage patterns. With the complex integrated circuits using techniques such as echo cancellation, Layer 1 Forward Error Correction (FEC), and prudent selection of voltage levels, the system achieves the 1Gigabit throughput.

41. Gigabit Ethernet (Cont’d)  9 voltage levels found on the cable in idle periods  During data transmission periods there are 17 voltage levels found on the cable. With this large number of states and the effects of noise, the signal on the wire looks more analog than digital. noise due to cable and termination problems.  Data from the sending station is divided into four parallel streams, encoded, transmitted and detected in parallel, and then reassembled into one received bit stream

42. 1000BASE-SX and LX  The IEEE 802.3 standard recommends that Gigabit Ethernet over fiber be the preferred backbone technology The timing, frame format, and transmission are common to all versions of 1000 Mbps. Two signal-encoding schemes are defined at the physical layer.  The 8B/ 10B scheme is used for optical fiber and shielded copper media  Pulse amplitude modulation 5 (PAM5) is used for UTP.

43. 1000BASE-SX and LX  1000BASE-X uses 8B/10B encoding converted to non-return to zero (NRZ) line encoding  NRZ encoding relies on the signal level found in the timing window to determine the binary value for that bit period  the determination of whether a bit is a zero or a one is made by the level of the signal rather than when the signal changes levels  The Media Access Control method treats the link as point-to-point. Since separate fibers are used for transmitting (Tx) and receiving (Rx) the connection is inherently full duplex. Gigabit Ethernet permits only a single repeater between two stations

44. 1000BASE-SX and LX

45. Gigabit Ethernet architecture 1000BASE LX 1000BASE SX

46. Gigabit Ethernet Architecture  Daisy-chaining, star, and extended star topologies are all allowed.  It is recommended that all links between a station and a hub or switch be configured for autonegotiation to permit the highest common performance.

47. Auto-negotiation  Detect cable type and speed of transmission automatically  Attempt to find highest mode of operation, in order 100BASE-TX of FX full duplex mode 100BASE-T4 100BASE-TX 10BASE-T full duplex 10BASE-T

48. Gigabit Ethernet – Physical  1000Base-SX Short wavelength, multimode fiber  1000Base-LX Long wavelength, Multi or single mode fiber  1000Base-CX Copper jumpers <25m, shielded twisted pair  1000Base-T 4 pairs, cat 5 UTP  Signaling - 8B/10B

49. Twisted pair  UTP - Unshielded Twisted-Pair twisting is used to minimize susceptibility due to interference and emission of radiation different twist rates help randomize and reduce coupling between different pairs  STP - Shielded Twisted-Pair metal shielding around conductors helps to reduce pickup and radiation more expensive

50. Cable Categories  Categories 1 and 2 low grade voice/data not suitable for LAN applications  Category 3 Data transmission up to 10 Mbps  Category 4 Data transmission up to 16 Mbps  Category 5 Data transmission up to 100 Mbps  Category 5e Full-duplex four-pair Fast Ethernet  Category 6 250 Mbps

51. 10BASET/100BASE-TX Wiring 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Transmit data + Received data + Received data - Transmit data - PCSwitch/uplink

52. Crossover Cable Wiring 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8 Transmit data + Received data + Received data - Transmit data - Transmit data + Received data + Received data - Transmit data - Switch

53. 10-Gigabit Ethernet  10-Gigabit Ethernet (10GbE) is evolving for not only LANs, but also MANs, and WANs. Frame format is the same, allowing interoperability between all varieties of legacy, fast, gigabit, and 10 Gigabit, with no reframing or protocol conversions. Bit time is now 0.1 nanoseconds. All other time variables scale accordingly. Since only full-duplex fiber connections are used, CSMA/CD is not necessary The IEEE 802.3 sublayers within OSI Layers 1 and 2 are mostly preserved, with a few additions to accommodate 40 km fiber links and interoperability with SONET/SDH technologies. Flexible, efficient, reliable, relatively low cost end-to-end Ethernet networks become possible.

54. 10-Gigabit Ethernet architectures  For 10 GbE transmissions, each data bit duration is 0.1 nanosecond.  Because of the short duration of the 10 GbE data bit, it is often difficult to separate a data bit from noise.  10 GbE data transmissions rely on exact bit timing to separate the data from the effects of noise on the physical layer. This is the purpose of synchronization.

55. 10-Gigabit Ethernet architectures  10-Gigabit Ethernet uses two separate encoding steps. By using codes to represent the user data, transmission is made more efficient. The encoded data provides synchronization, efficient usage of bandwidth, and improved Signal-to-Noise Ratio characteristics Signals broken into 4 separate streams 4 laser sources used to provide optical signal Optical signal is sent through multiplexer Multiplexed signal sent onto fiber medium

56. Future of Ethernet  The future of networking media is three-fold: Copper (up to 1000 Mbps, perhaps more) Wireless (approaching 100 Mbps, perhaps more) Optical fiber (currently at 10,000 Mbps and soon to be more) Copper and wireless media have certain physical and practical limitations on the highest frequency signals that can be transmitted. Not a limiting factor for optical fiber in the foreseeable future.  The bandwidth limitations on optical fiber are extremely large and are not yet being threatened. In fiber systems, it is the electronics technology (such as emitters and detectors) and fiber manufacturing processes that most limit the speed.

57. 10 Gigabit Ethernet  IEEE 802.3ae was adapted to include 10-Gbps full-duplex transmission over fiber-optic cable.  When using single-mode fiber as the transmission medium, the maximum transmission distance is 40 kilometers (25 miles).  Some discussions between IEEE members have begun that suggest the possibility of standards for 40-, 80-, and even 100- Gbps Ethernet.

58. Future of Ethernet  Ethernet has gone through an evolution from Legacy → Fast → Gigabit → MultiGigabit technologies.  The future of networking media is threefold: Copper (up to 1000 Mbps, perhaps more) Wireless (approaching 100 Mbps, perhaps more) Optical fiber (currently at 10,000 Mbps and soon to be more)

59. The End