2. Jozef Goetz, 2012 1 expanded by Jozef Goetz, 2012 The McGraw-Hill Companies, Inc., 2006

3. Jozef Goetz, 2012 2 13-1 IEEE STANDARDS In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication among equipment from a variety of manufacturers.In 1985, the Computer Society of the IEEE started a project, called Project 802, to set standards to enable intercommunication among equipment from a variety of manufacturers. Standard 802 adopted by ANSI and approved by ISO is a way of specifying functions of the physical layer and the data link layer of major LAN protocols.Standard 802 adopted by ANSI and approved by ISO is a way of specifying functions of the physical layer and the data link layer of major LAN protocols. Data Link Layer Physical Layer Topics discussed in this section:

4. Jozef Goetz, 2012 3 INTRODUCTION The key technology ingredients that determine the nature of a LAN are: [1] Topology [2] Transmission medium [3] Medium access control technique LANs usually are owned by the organization that is using the network to interconnect equipment. LANs have much greater capacity than WAN.

5. Jozef Goetz, 2012 4 LAN ARCHITECTURE In OSI terms, higher-layer protocols (layer 3/4 & above) are independent of network architecture and are applicable to LANs & WANs. SCOPE OF IEEE 802 STANDARDS [1] LOGICAL LINK CONTROL (LLC) [2] MEDIUM ACCESS CONTROL (MAC) [3] PHYSICAL LAYER

6. Jozef Goetz, 2012 5 Figure 13.1 IEEE standard for LANs Note: there is one LLC sublayer for all IEEE LANs

7. Jozef Goetz, 2012 6 LAN ARCHITECTURE Physical Layer [1] Encoding/decoding of signals [2] Preamble generation/removal (synch) [3] Bit transmission/reception Medium Access Layer (MAC) [1] On transmission, assemble data into a frame with address and error-detection fields. [2] On reception, disassemble frame, and perform recognition and error detection. [3] Govern access to the LAN transmission medium

8. Jozef Goetz, 2012 7 LAN ARCHITECTURE Logical Link Control (LLC) [1] Provide an interface to higher layers and perform flow and error control. LAN Protocols in Context

9. Jozef Goetz, 2012 8 Figure 13.2 HDLC (typical DLL protocol) frame compared with LLC and MAC frames in the 803 IEEE standard PDU – protocol data unit

10. Jozef Goetz, 2012 9 LOGICAL LINK CONTROL 3 services are provided by LLC: [1] Connection-mode service A logical connection is set up between users. Flow/error control. Extended HDLC format. [2] Acknowledged connectionless service No connection is setup up, but datagrams are acknowledged. [3] Unacknowledged connection service Simple, the delivery of data is not guaranteed.

11. Jozef Goetz, 2012 10 LOGICAL LINK CONTROL

12. Jozef Goetz, 2012 11 LOGICAL LINK CONTROL Most upper-layer protocols such as IP don’t use the services of LLC

13. Jozef Goetz, 2012 12 Ethernet Cabling (a) Linear – from room to room, (b) Vertical Spine – from the basement to the roof with cables on each floor connected by repeaters, (c) Tree, (d) Segmented – see max in the previous slide repeaters are the physical layer device – amplifies signals in both directions

14. Jozef Goetz, 2012 13 Gigabit Ethernet (a) A two-station Ethernet. (b) A multistation Ethernet.

15. Jozef Goetz, 2012 14 LAN TOPOLOGIES The common topologies for LANs are bus, tree, ring, and star. STARRING TREE BUS

16. Jozef Goetz, 2012 15 Three generations of Ethernet

17. Jozef Goetz, 2012 16 13-2 STANDARD ETHERNET The original Ethernet was created in 1976 at Xerox’s Palo Alto Research Center (PARC).The original Ethernet was created in 1976 at Xerox’s Palo Alto Research Center (PARC). Since then, it has gone through four generations.Since then, it has gone through four generations. We briefly discuss the Standard (or traditional) Ethernet in this section.We briefly discuss the Standard (or traditional) Ethernet in this section. MAC Sublayer Physical Layer Topics discussed in this section:

18. Jozef Goetz, 2012 17 Figure 13.3 Ethernet evolution through four generations

19. Jozef Goetz, 2012 18 Ethernet A thick coax cable was used for data transmission. The coax could be up to 2.5km long (with repeaters every 500 meters). 256 machines could connect to the cable. A cable with multiple machines is called a multidrop cable. The original throughput was 2.94 Mbps

20. Jozef Goetz, 2012 19 IEEE 802.3 Based on 1-persistent CSMA/CD with some extra features. More commonly (but incorrectly) referred to as Ethernet. Ethernet is the original product designed by Xerox PARC based on Bob Metcalfe's idea It was later upgraded to 10 Mbps by Xerox, Intel and DEC. This formed the basis for the IEEE 802.3 standard. Which then became an ISO standard.

21. Jozef Goetz, 2012 20 Ethernet – IEEE 802.3 in ’83. LAN Architecture of the original Ethernet. A multidrop cabel A computer first listened to the cable to see if someone was already transmitting. If so, then back off and wait a random time before retrying If a 2 nd collision happen, the random waiting time is doubled Other standards a token bus (IEEE 802.4) and a token ring (IEEE 802.5) Ethernet (most popular LAN) won a war between Ethernet, token bus, token ring

22. Jozef Goetz, 2012 21 Ethernet What happens when there is a collision on Ethernet? The terminals listen while transmitting, and if they don’t hear the same thing that they transmitted, they jam the cable to alert the other terminals that a collision has happened. They then back off and wait a random time before trying again.

23. Jozef Goetz, 2012 22 Ethernet Cabling 4 kinds of Ethernet cabling. 10Base5 => 1 st one =10 means 10 Mbps – the speed in Mbps; Base = baseband transmission, 3 rd one is its length rounded to 100 m (a) 10Base5, (b) 10Base2 – much cheaper and easier to install, (c) 10Base-T – cheapest, no share cable. (d) 10Base-F – fiber optic, excellent noise immunity, good security

24. Jozef Goetz, 2012 23 IEEE 802.3 10-Mbps Specs (ETHERNET)

25. Jozef Goetz, 2012 24 MAC FRAME FORMAT The MAC layer receives a block of data from the LLC layer and is responsible for performing functions related to medium access and for transmitting the data. MAC control ex. Priority level PDU – protocol data unit

26. Jozef Goetz, 2012 25 802.3 MAC frame Minimum and maximum length Ethernet does not provide any mechanism for acknowledging received frames, making it what is known as an unreliable medium. Acknowledgments must be implemented at the higher layers. Start Frame Delimiter physical next length or PDU ( protocol data unit) packet physical Preamble is added at the physical layer Data encapsulated from the upper-layer protocols

27. Jozef Goetz, 2012 26 802.3 MAC frame Minimum and maximum length Start Frame Delimiter physical next length or PDU packet physical Preamble is added at the physical layer DSAP = Destination Service Access Point Defines a number to which a higher layer protocol or application is bound to at the destination, e.g. IP SSAP = Source Service Access Point Tells the destination which SAP to send back the response to, e.g. IP Control information depends on the service type Type 1 – no other information required Type 2 – full sliding window protocol implementation with extensions Type 3 – basic stop and wait protocol information

28. Jozef Goetz, 2012 27 Each station on an Ethernet network (such as a PC, workstation, or printer) has its own Network Interface Card (NIC). The NIC fits inside the station and provides the station with a 6-byte physical address. written in hexadecimal notation using a hyphen to separate bytes from each other Ethernet addresses in hexadecimal notation

29. Jozef Goetz, 2012 28 Figure 13.6 Example of an Ethernet address in hexadecimal notation

30. Jozef Goetz, 2012 29 Unicast and multicast addresses The least significant bit of the first byte defines the type of address. If the bit is 0, the address is unicast; otherwise, it is multicast.

31. Jozef Goetz, 2012 30 The broadcast destination address is a special case of the multicast address in which all bits are 1s. FF:FF:FF:FF:FF:FF Note

32. Jozef Goetz, 2012 31 Define the type of the following destination addresses: a. 4A:30:10:21:10:1A b. 47:20:1B:2E:08:EE c. FF:FF:FF:FF:FF:FF Solution To find the type of the address, we need to look at the second hexadecimal digit from the left. If it is even, the address is unicast. If it is odd, the address is multicast. If all digits are F’s, the address is broadcast. Therefore, we have the following: a. This is a unicast address because A in binary is 1010. b. This is a multicast address because 7 in binary is 0111. c. This is a broadcast address because all digits are F’s. Example 13.1

33. Jozef Goetz, 2012 32 Show how the address 47:20:1B:2E:08:EE is sent out on line. Solution The address is sent left-to-right, byte by byte; for each byte, it is sent right-to-left, bit by bit, as shown below: e.g. 47 = 0100 0111 => 1110 0010 Example 13.2

34. Jozef Goetz, 2012 33 Physical layer

35. Jozef Goetz, 2012 34 AUI NIC – Network Interface Card

36. Jozef Goetz, 2012 35 Function of MAU (transceiver) AUI – Attachment Unit Interface MAU – Medium Attachment Unit MDI – Medium Dependent Interface PLS – Physical Layer Signaling NIC – Network Interface Card

37. Jozef Goetz, 2012 36 Function of MAU (transceiver) MDI – Medium Dependent Interface PLS – Physical Layer Signaling It creates the appropriate signal for each particular medium. There is a MAU for each type of medium used in 10-Mbps Ethernet. the coaxial cable needs its own type of MAU, the twisted-pair medium needs a twisted-pair MAU, and fiber-optic cable needs a fiber­optic MAU.

38. Jozef Goetz, 2012 37 NIC Evolution Volumes for Ethernets NICs became huge NIC becomes cheaper than the AUI cable! Moved from 3 separate components to one integral NIC card

39. Jozef Goetz, 2012 38 Categories of traditional Ethernet cables Thick coaxial one segment is 500m long max Thin coaxial one segment is 185m long max UTP category 5 100m max P2P Optical Fiber 2km max P2P P2P = point-to-pointUnshielded Twisted-Pair

40. Jozef Goetz, 2012 39 BUS LANs 4 media that can be used for a bus LAN: [1] Twisted pair, [2] Baseband coaxial cable, [3] Broadband coaxial cable, [4] Optical fiber. 10BASE 5 - thick cable 10BASE2 - thin cable

41. Jozef Goetz, 2012 40 Figure 13.10 10Base5 implementation

42. Jozef Goetz, 2012 41 Connection of a station to the medium using 10Base5 the size of the cable, which is roughly the size of a garden hose and too stiff to bend with your hands AIU cable

43. Jozef Goetz, 2012 42 Figure 13.11 10Base2 implementation

44. Jozef Goetz, 2012 43 Connection of stations to the medium using 10Base2 uses a bus topology with 1.an internal transceiver Note that if the station uses an internal transceiver, there is no need for an AUI cable. 2.a point-to-point connection via an external transceiver If the station lacks a transceiver, then an external transceiver can be used in conjunction with the AUI - Attachment Unit Interface. AIU cable Connection of stations to the medium using 10Base5

45. Jozef Goetz, 2012 44 Figure 13.12 10Base-T implementation

46. Jozef Goetz, 2012 45 Connection of stations to the medium using 10Base-T uses a physical star topology. The stations are connected to a repeater hub with 1.an internal transceiver Note that if the station uses an internal transceiver, there is no need for an AUI cable. 2.a point-to-point connection via an external transceiver If the station lacks a transceiver, then an external transceiver can be used in conjunction with the AUI - Attachment Unit Interface. Each UTP (Unshielded Twisted-Pair) cable can be up to 100m long (max network size = 200m) A repeater hub connects segments of a LAN. A repeater forwards every frame; it has no filtering capability.

47. Jozef Goetz, 2012 46 Ethernet Ethernet now looks like a star network from a physical perspective Hub is a half duplex device – “effectively a small piece of coaxial cable” Collisions on a hub can still take place

48. Jozef Goetz, 2012 47 Figure 13.13 10Base-F implementation

49. Jozef Goetz, 2012 48 Connection of stations to the medium using 10Base-FL uses a star topology. The stations are connected to a repeater hub with 1.an external transceiver (a point-to-point connection) The standard is normally implemented using an external transceiver called fiber- optic MAU. The station is connected to the external transceiver by an AUI cable. The transceiver is connected to the hub by using two pairs of fiber-optic cables AUI cabel

50. Jozef Goetz, 2012 49 Comparison of Connection of stations to the medium 10Base510Base2

51. Jozef Goetz, 2012 50

52. Jozef Goetz, 2012 51 Table 13.1 Summary of Standard Ethernet implementations

53. Jozef Goetz, 2012 52 13-3 CHANGES IN THE STANDARD The 10-Mbps Standard Ethernet has gone through several changes before moving to the higher data rates.The 10-Mbps Standard Ethernet has gone through several changes before moving to the higher data rates. These changes actually opened the road to the evolution of the Ethernet to become compatible with other high- data-rate LANs.These changes actually opened the road to the evolution of the Ethernet to become compatible with other high- data-rate LANs. Bridged Ethernet Switched Ethernet Full-Duplex Ethernet Topics discussed in this section:

54. Jozef Goetz, 2012 53 A network with and without a bridge The first step in the Ethernet evolution was the division of a LAN by bridges. Bridges have two effects on an Ethernet LAN: They raise the bandwidth and separate collision domains. Without bridging, 12 stations contend for access to the medium; with bridging only 6 stations contend for access to the medium.

55. Jozef Goetz, 2012 54 Sharing bandwidth In an unbridged Ethernet network, the total capacity (10 Mbps) is shared between all stations with a frame to send; If only one station has frames to send, it benefits from the total capacity (10 Mbps). But if more than one station needs to use the network, the capacity is shared. For example, if 2 stations have a lot of frames to send, they probably alternate in usage. When one station is sending, the other one refrains from sending (a and b). We can say that, on average, each station sends at the rate of 5 Mbps.

56. Jozef Goetz, 2012 55 A network with and without a bridge A bridge divides the network into two or more networks. Bandwidthwise, each network is independent. a network with 12 stations is divided into two networks, each with 6 stations. Now each network has a capacity of 10 Mbps. The 10-Mbps capacity in each segment is now shared between 6 stations (actually 7 because the bridge acts as a station in each segment), not 12 stations. In a network with a heavy load, each station theoretically is offered 10/6 Mbps instead of 10/12 Mbps, assuming that the traffic is not going through the bridge.

57. Jozef Goetz, 2012 56 Collision domains in a nonbridged and bridged network each station is now offered 10/3 Mbps, which is 4 times more than a nonbridged network.

58. Jozef Goetz, 2012 57 Hub In an Ethernet network there are 4 devices that from the outside look very similar. A hub is the simplest of these devices. Any data packet coming from one port is sent to all other ports. It is then up to the receiving computer to decide if the packet is for it. Imagine packets going through a hub as messages going into a mailing list. The mail is sent out to everyone and it is up to the receiving party to decide if it is of interest. The biggest problem with hubs is their simplicity. Since every packet is sent out to every computer on the network, there is a lot of wasted transmission. This means that the network can easily become bogged down. Hubs are typically used on small networks where the amount of data going across the network is never very high.

59. Jozef Goetz, 2012 58 Bridge Bridge A bridge goes one step up on a hub in that it looks at the destination of the packet before sending. If the destination address is not on the other side of the bridge it will not transmit the data. A bridge only has one incoming and one outgoing port. To build on the email analogy above, the bridge is allowed to decide if the message should continue on. It reads the address bob@smith.com and decides if there is a bob@smith.com on the other side. If there isn’t, the message will not be transmitted. Bridges are typically used to separate parts of a network that do not need to communicate regularly, but still need to be connected.

60. Jozef Goetz, 2012 59 Bridges Basic Filtering _ Detect which frames need to go from one LAN to another Forwarding _ Send those frames from the incoming LAN to the outgoing LAN _ “Drop” those frames that don’t need to be forwarded Loop Prevention _ Avoid issues with networks where a frame can keep going round and round Types of Bridges Static Dynamic – called learning bridges

61. Jozef Goetz, 2012 60 BRIDGES In virtually all cases, there is a need to expand beyond the confines of a single LAN, to provide interconnection to other LANs and to WAN. The bridge is a simpler device than a router and provides a means of interconnecting similar LANs.

62. Jozef Goetz, 2012 61 BRIDGES

63. Jozef Goetz, 2012 62 BRIDGES - FIXED ROUTING Each bridge must make a decision whether or not to retransmit the frame on its other LAN, in order to move it closer to its intended destination.

64. Jozef Goetz, 2012 63 Switch A switch steps up on a bridge in that it has multiple ports. When a packet comes through a switch it is read to determine which computer to send the data to. This leads to increased efficiency in that packets are not going to computers that do not require them. Now the email analogy has multiple people able to send email to multiple users. The switch can decide where to send the mail based on the address. Most large networks use switches rather than hubs to connect computers within the same subnet.

65. Jozef Goetz, 2012 64 ROUTER A router is similar in a switch in that it forwards packets based on address. But, instead of the MAC address that a switch uses, a router can use the IP address. This allows the network to go across different protocols. The most common home use for routers is to share a broadband internet connection. The router has a public IP address and that address is shared with the network. When data comes through the router it is forwarded to the correct computer. This comparison to email gets a little off base. This would be similar to the router being able to receive a packet as email and sending it to the user as a fax.

66. Jozef Goetz, 2012 65 Switched Ethernet The idea of a bridged LAN can be extended to a switched LAN. Instead of having two to four networks, why not have N networks, where N is the number of stations on the LAN? A layer 2 switch is an N-port bridge with additional sophistication that allows faster handling of the packets

67. Jozef Goetz, 2012 66 HUBs & SWITCHES HUB SWITCH Hubs are commonly used to connect segments of a LAN.segmentsLAN A hub contains multiple ports.ports When a packet arrives at one port, it is copied to the other ports so that all segments of the LAN can see all packets.packet

68. Jozef Goetz, 2012 67 Full-duplex switched Ethernet One of the limitations of 1OBase5 and 1OBase2 is that communication is half-duplex (1OBase-T is always full-duplex); The next step in the evolution was to move from switched Ethernet to full­duplex switched Ethernet = to 20 Mbps

69. Jozef Goetz, 2012 68 No Need for CSMA/CD In full-duplex switched Ethernet, there is no need for the Carrier Sense Multiple Access with Collision Detection - CSMA/CD method. Each station or switch can send and receive independently without worrying about collision. Each link is a point-to-point separate dedicated path between the station and the switch. There is no more need for carrier sensing; there is no more need for collision detection. -’s: There is no explicit flow control or error control to inform the sender that the frame has arrived at the destination without error.. To provide it, a new sublayer, called the MAC control, is added between the LLC sublayer and the MAC sublayer.

70. Jozef Goetz, 2012 69 13-4 FAST ETHERNET – IEEE 802.3u Fast Ethernet was designed to compete with LAN protocols such as FDDI or Fiber Channel.Fast Ethernet was designed to compete with LAN protocols such as FDDI or Fiber Channel. IEEE created Fast Ethernet under the name 802.3u.IEEE created Fast Ethernet under the name 802.3u. Fast Ethernet is backward-compatible with Standard Ethernet, but it can transmit data 10 times faster at a rate of 100 Mbps.Fast Ethernet is backward-compatible with Standard Ethernet, but it can transmit data 10 times faster at a rate of 100 Mbps. MAC Sublayer Physical Layer Topics discussed in this section:

71. Jozef Goetz, 2012 70 13-4 FAST ETHERNET CONCEPT - The whole idea in the evolution of Ethernet from 10 to 100 Mbps is to keep the MAC sublayer untouched. -The access method is the same (CSMA/CD). -for full-duplex there is no need for CSMA/CD. -Backward compatibility with traditional Ethernet. -Frame format, minimum and maximum frame lengths, and addressing are the same for 10- and 100-Mbps Ethernet.

72. Jozef Goetz, 2012 71 Figure 13.19 Fast Ethernet topology

73. Jozef Goetz, 2012 72 autonegotiation A new feature added to Fast Ethernet It allows to have : a station or a hub a range of capabilities a station to check a hub's capabilities. to negotiate the mode or data rate of operation. purposes: to allow incompatible devices to connect to one another. For example, a device with a maximum capacity of 10 Mbps can communicate with a device that is designed for 100 Mbps (but can work at a lower rate).

74. Jozef Goetz, 2012 73 Fast Ethernet implementations Fast Ethernet can be categorized as either a two-wire or a four- wire implementation. The two-wire implementation is called 100Base-X, which can be either twisted-pair cable (100Base-TX) or fiber-optic cable (100Base-FX). The four-wire implementation is designed only for twisted- pair cable (100Base-T4).

75. Jozef Goetz, 2012 74 IEEE 802.3 100-Mbps Specs (ETHERNET)

76. Jozef Goetz, 2012 75 Fast Ethernet 802.3u The original fast Ethernet cabling. People needed to go faster than 10Mbps, so we needed a faster Ethernet. Instead of going with a new protocol, it was decided to just make regular Ethernet go faster – IEEE 802.3u. This was done by reducing the bit time from 100nsec to 10 nsec and keeping backward compatible – frame formats, interfaces and rules Note: that 10Base2 and 10Base5 were not included – it was based only on 10BaseT Only two lines are used – one wire in and one wire out of the station. This makes 100BaseTX full-duplex – able to handle 100 Mbps in either direction at the same time. all switches can handle a mix of 10- and 100 Mbps stations The (slower) 100BaseT4 and 100BaseTX are collectively referred to as “100BaseT” Uses “Category 5 UTP” clock @ 125 MHz or 100m hubs not permitted Uses “Category 3 UTP” clock @ 25 MHz 2 twisted pairs per station 4 twisted pairs per station

77. Jozef Goetz, 2012 76 Fast Ethernet physical layer RS in Fast Ethernet replaces the PLS sublayer in 10-Mbps Ethernet. Encoding and decoding, which were performed by the PLS, are moved to the PHY sublayer (transceiver) because encoding in Fast Ethernet is medium-dependent. The reconciliation sublayer RS is responsible for the passing of data in 4-bit format (nibble) to the MII The MII is an improved interface that can be used with both a 10- and 100. the AUI was replaced with (MII)

78. Jozef Goetz, 2012 77 MII transceiver in Fast Ethernet is responsible for encoding and decoding. can be external or internal. An external transceiver is installed close to the medium and is connected via an MII cable to the station. An internal transceiver is installed inside the station (on the interface card) and does not need an MII cable. transceiver is medium-dependent, a medium­dependent interface (MDI) is just a piece of hardware that is implementation­specific.

79. Jozef Goetz, 2012 78 100Base-TX implementation The transceiver is responsible for transmitting, sending, detecting the collision, and encoding/decoding.

80. Jozef Goetz, 2012 79 Encoding and decoding in 100Base-TX To maintain synchronization, the encoder first performs block encoding. The 4 parallel bits received from the NIC is encoded into 5 serial bits using 4B/5B. This requires a bandwidth of 125 MHz (125 Mbps). The data at the 125-Mbps rate are then encoded into a signal using MLT-3

81. Jozef Goetz, 2012 80 100Base-FX implementation 100Base-TX implementation

82. Jozef Goetz, 2012 81 Encoding and decoding in 100Base-FX Encoding and Decoding 100Base-FX uses two levels of encoding To maintain synchronization, the encoder first performs block encoding. The 4 parallel bits received from the NIC is encoded into 5 serial bits using 4B/SB. This requires a bandwidth of 125 MHz (125 Mbps). The data at the 125-Mbps rate are then encoded into a signal using NRZ-I Encoding and decoding in 100Base-TX

83. Jozef Goetz, 2012 82 100Base-T4 implementation it requires the use of category 5 UTP or STP (shielded twisted-pair) cable. A new standard, called 100Base­T4, was designed to use category 3 or higher UTP. The implementation uses four pairs of UTP for transmitting 100 Mbps. 100Base-FX implementation 100Base-TX implementation

84. Jozef Goetz, 2012 83 Using four wires in 100Base-T4 Transmission Using Four Wires The 8B/6T encoding reduces the bandwidth from 100 to 75 Mbaud (ratio of 8/6). However, a voice-grade UTP is not capable of handling even this bandwidth. 100Base-T4 is designed to operate on 25-Mbaud bandwidths. It cuts to 4 pairs – see the picture

85. Jozef Goetz, 2012 84 13.84 Summary of Encoding for Fast Ethernet implementation

86. Jozef Goetz, 2012 85 Table 13.2 Summary of Fast Ethernet implementations

87. Jozef Goetz, 2012 86 13-5 GIGABIT ETHERNET – IEEE 802.3z The need for an even higher data rate resulted in the design of the Gigabit Ethernet protocol (1000 Mbps). The IEEE committee calls the standard 802.3z. It allows the internet interconnection of existing LANs into a Metropolitan Area Network (MAN) or a Wide Area Network (WAN) MAC Sublayer Physical Layer Ten-Gigabit Ethernet Topics discussed in this section:

88. Jozef Goetz, 2012 87 Gigabit Ethernet (a) A two-station Ethernet. (b) A multistation Ethernet.

89. Jozef Goetz, 2012 88 Figure 13.22 Topologies of Gigabit Ethernet

90. Jozef Goetz, 2012 89 Gigabit Ethernet implementations Gigabit Ethernet can be categorized as either a two-wire or a four- wire implementation. The two-wire implementation is called 1000Base-X, which can use shortwave optical fiber (1000Base-SX), long-wave optical fiber (1000Base-LX), or short copper jumpers (1000Base-CX). The four-wire version uses twisted-pair cable (1000Base-T). Unshielded Twisted-PairShielded Twisted-Pair

91. Jozef Goetz, 2012 90 Gigabit Ethernet Gigabit Ethernet cabling. 10 times faster than fast Ethernet and still is backwards compatible. supports both copper and fiber cabling All configurations are point-to-point. Compatible with technologies: FrameRelay and ATM It supports two modes – full-duplex and half-duplex. Full-duplex – no collisions – uses a switch Half-duplex – has collisions – uses a hub Encoding rules called 8B/10B each 8-bit byte is encoded on the fiber as 10 bits hence the name 8B/10B Manchester encoding required a 2 Gbaud at 1 Gbps, so >> too wasteful of bandwidth 1.3 micron laser 0.85 and 1.3 micron laser

92. Jozef Goetz, 2012 91 In the full-duplex mode of Gigabit Ethernet, there is no collision; the maximum length of the cable is determined by the signal attenuation in the cable. Note

93. Jozef Goetz, 2012 92 IEEE 802.2: LLC Logical Link Control (a) Position of LLC. Hides the differences between various kind of 802 networks by providing a single format and interface to the network layer (b) Protocol formats. LLC header contains: a destination access point, a source access point and a control field which contains a seq and acknowledgement numbers

94. Jozef Goetz, 2012 93 Physical layer in Gigabit Ethernet

95. Jozef Goetz, 2012 94 1000Base-X implementation Both 1000Base-SX and 1000Base-LX use two fiber-optic cables. The only difference between them is that the former uses shortwave laser and the latter uses long-wave laser. designed with an internal transceiver, so there is no external GMII cable or connector.

96. Jozef Goetz, 2012 95 1000Base-T implementation 1000Base-X implementation

97. Jozef Goetz, 2012 96 Encoding in 1000Base-T 5 levels of pulse amplitude modulation are used. The technique is very complicated and beyond the scope of this book.

98. Jozef Goetz, 2012 97 Summary: Encoding/decoding in Gigabit Ethernet implementations

99. Jozef Goetz, 2012 98 Table 13.3 Summary of Gigabit Ethernet implementations IEEE 802.3z Standard IEEE 802.3z Table 13.4 Summary of Ten-Gigabit Ethernet implementations Standard IEEE 802.3ae Ten-Gigabit Ethernet uses fiber optic cable over long distances and operates in full duplex mode which means there is no need for contention; CSMA/CD is not used in Ten-Gigabit Ethernet. Make it compatible with Standard, Fast, and Gigabit Ethernet

100. Jozef Goetz, 2012 99 Ethernet advantages 1. simple and flexible 2. reliable 3. cheap twisted pair wiring is relatively inexpensive interface cards are low cost 4. easy to maintain no software to install (other than drivers) no configuration table to manage 5. interworks easily with TCP/IP IP is a connectionless protocol, so fits perfectly with Ethernet IP fits much less well with ATM, which is connection oriented

101. Jozef Goetz, 2012 100 Summary UTP - unshielded twisted-pair cable

102. Jozef Goetz, 2012 101 Table 13.3 Summary of Gigabit Ethernet implementations Table 13.4 Summary of Ten-Gigabit Ethernet implementations Standard IEEE 802.3ae Summary Table 13.1 Summary of Standard Ethernet implementations Table 13.2 Summary of Fast Ethernet implementations