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HIGH SPEED NETWORKS

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HIGH SPEED NETWORKS

HIGH SPEED NETWORKS

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  • 1. P13ITE05 High Speed Networks UNIT - I Dr.A.Kathirvel Professor & Head/IT - VCEW
  • 2. UNIT - I  Frame Relay Networks  Asynchronous transfer mode  ATM protocol architecture  ATM logical connection  ATM cell and service categories – AAL   High speed LANs: Fast, Gigabit ethernet, Fiber channel Wireless LANs
  • 3. Introduction  Packet-Switching Networks     Switching Technique Routing X.25 Frame Relay Networks    Architecture User Data Transfer Call Control 3
  • 4. Packet-Switching Networks     Basic technology the same as in the 1970s One of the few effective technologies for long distance data communications Frame relay and ATM are variants of packetswitching Advantages: - flexibility, resource sharing, robust, responsive  Disadvantages:   Time delays in distributed network, overhead penalties Need for routing and congestion control 4
  • 5. Circuit-Switching    Long-haul telecom network designed for voice Network resources dedicated to one call Shortcomings when used for data:   Inefficient (high idle time)‫‏‬ Constant data rate 5
  • 6. Packet-Switching     Data transmitted in short blocks, or packets Packet length < 1000 octets Each packet contains user data plus control info (routing)‫‏‬ Store and forward 6
  • 7. Figure 4.1 The Use of Packets Chapter 4 Frame Relay 7
  • 8. Figure 4.2 Packet Switching: Datagram Approach Chapter 4 Frame Relay 8
  • 9. Advantages over Circuit-Switching    Greater line efficiency (many packets can go over shared link)‫‏‬ Data rate conversions Non-blocking under heavy traffic (but increased delays)‫‏‬ 9
  • 10. Disadvantages relative to Circuit-Switching     Packets incur additional delay with every node they pass through Jitter: variation in packet delay Data overhead in every packet for routing information, etc Processing overhead for every packet at every node traversed 10
  • 11. Figure 4.3 Simple Switching Network Chapter 4 Frame Relay 11
  • 12. Switching Technique    Large messages broken up into smaller packets Datagram  Each packet sent independently of the others  No call setup  More reliable (can route around failed nodes or congestion)‫‏‬ Virtual circuit  Fixed route established before any packets sent  No need for routing decision for each packet at each node 12
  • 13. Figure 4.4 Packet Switching: VirtualCircuit Approach Chapter 4 Frame Relay 13
  • 14. Routing    Adaptive routing Node/trunk failure Congestion 14
  • 15. X.25     3 levels Physical level (X.21)‫‏‬ Link level (LAPB, a subset of HDLC)‫‏‬ Packet level (provides virtual circuit service)‫‏‬ 15
  • 16. Figure 4.5 The Use of Virtual Circuits Chapter 4 Frame Relay 16
  • 17. Figure 4.6 User Data and X.25 Protocol Control Information Chapter 4 Frame Relay 17
  • 18. Frame Relay Networks      Designed to eliminate much of the overhead in X.25 Call control signaling on separate logical connection from user data Multiplexing/switching of logical connections at layer 2 (not layer 3)‫‏‬ No hop-by-hop flow control and error control Throughput an order of magnitude higher than X.25 18
  • 19. Figure 4.7 Comparison of X.25 and Frame Relay Protocol Stacks Chapter 4 Frame Relay 19
  • 20. Figure 4.8 Virtual Circuits and Frame Relay Virtual Connections Chapter 4 Frame Relay 20
  • 21. Frame Relay Architecture     X.25 has 3 layers: physical, link, network Frame Relay has 2 layers: physical and data link (or LAPF)‫‏‬ LAPF core: minimal data link control  Preservation of order for frames  Small probability of frame loss LAPF control: additional data link or network layer end-to-end functions 21
  • 22. LAPF Core      Frame delimiting, alignment and transparency Frame multiplexing/demultiplexing Inspection of frame for length constraints Detection of transmission errors Congestion control 22
  • 23. LAPF-core Formats 23
  • 24. User Data Transfer   No control field, which is normally used for:  Identify frame type (data or control)‫‏‬  Sequence numbers Implication:  Connection setup/teardown carried on separate channel  Cannot do flow and error control 24
  • 25. Frame Relay Call Control   Frame Relay Call Control Data transfer involves:    Establish logical connection and DLCI Exchange data frames Release logical connection 25
  • 26. Frame Relay Call Control 4 message types needed  SETUP  CONNECT  RELEASE  RELEASE COMPLETE 26
  • 27. ATM Protocol Architecture    Fixed-size packets called cells Streamlined: minimal error and flow control 2 protocol layers relate to ATM functions:    Common layer providing packet transfers Service dependent ATM adaptation layer (AAL)‫‏‬ AAL maps other protocols to ATM 27
  • 28. Protocol Model has 3 planes    User Control management 28
  • 29. 29
  • 30. Logical Connections   VCC (Virtual Channel Connection): a logical connection analogous to virtual circuit in X.25 VPC (Virtual Path Connection): a bundle of VCCs with same endpoints 30
  • 31. Figure 5.2 Chapter 2 Protocols and the TCP/IP Suite 31
  • 32. Advantages of Virtual Paths     Simplified network architecture Increased network performance and reliability Reduced processing and short connection setup time Enhanced network services 32
  • 33. 33
  • 34. VCC Uses    Between end users Between an end user and a network entity Between 2 network entities 34
  • 35. Figure 5.3 Chapter 2 Protocols and the TCP/IP Suite 35
  • 36. VPC/VCC Characteristics      Quality of Service (QoS)‫‏‬ Switched and semi-permanent virtual channel connections Cell sequence integrity Traffic parameter negotiation and usage monitoring (VPC only) virtual channel identifier restriction within a VPC 36
  • 37. Control Signaling   A mechanism to establish and release VPCs and VCCs 4 methods for VCCs:     Semi-permanent VCCs Meta-signaling channel User-to-network signaling virtual channel User-to-user signaling virtual channel 37
  • 38. Control Signaling  3 methods for VPCs  Semi-permanent  Customer controlled  Network controlled 38
  • 39. ATM Cells      Fixed size 5-octet header 48-octet information field Small cells reduce delay for high-priority cells Fixed size facilitate switching in hardware 39
  • 40. Header Format       Generic flow control Virtual path identifier (VPI)‫‏‬ Virtual channel identifier (VCI)‫‏‬ Payload type Cell loss priority Header error control 40
  • 41. Figure 5.4 Chapter 2 Protocols and the TCP/IP Suite 41
  • 42. Generic Flow Control   Control traffic flow at user-network interface (UNI) to alleviate short-term overload conditions When GFC enabled at UNI, 2 procedures used:  Uncontrolled transmission  Controlled transmission 42
  • 43. 43
  • 44. Header Error Control     8-bit field calculated based on remaining 32 bits of header error detection in some cases, error correction of single-bit errors in header 2 modes:  error detection  Error correction 44
  • 45. Figure 5.5 Chapter 2 Protocols and the TCP/IP Suite 45
  • 46. Figure 5.6 Chapter 2 Protocols and the TCP/IP Suite 46
  • 47. Figure 5.7 Chapter 2 Protocols and the TCP/IP Suite 47
  • 48. Service Categories  Real-time service  Constant bit rate (CBR)‫‏‬  Real-time variable bit rate (rt-VBR)‫‏‬  Non-real-time service  Non-real-time variable bit rate (nrt-VBR)‫‏‬  Available bit rate (ABR)‫‏‬  Unspecified bit rate (UBR)‫‏‬  Guaranteed frame rate (GFR)‫‏‬ 48
  • 49. Figure 5.8 Chapter 2 Protocols and the TCP/IP Suite 49
  • 50. ATM Adaptation Layer (ATM)‫‏‬  Support non-ATM protocols  e.g.,  PCM voice, LAPF AAL Services  Handle transmission errors  Segmentation/reassembly (SAR)‫‏‬  Handle lost and misinserted cell conditions  Flow control and timing control 50
  • 51. Applications of AAL and ATM       Circuit emulation (e.g., T-1 synchronous TDM circuits)‫‏‬ VBR voice and video General data services IP over ATM Multiprotocol encapsulation over ATM (MPOA)‫‏‬ LAN emulation (LANE)‫‏‬ 51
  • 52. AAL Protocols  AAL layer has 2 sublayers:  Convergence Sublayer (CS)‫‏‬  Supports specific applications using AAL  Segmentation and Reassembly Layer (SAR)‫‏‬  Packages data from CS into cells and unpacks at other end 52
  • 53. Figure 5.9 Chapter 2 Protocols and the TCP/IP Suite 53
  • 54. Figure 5.10 Chapter 2 Protocols and the TCP/IP Suite 54
  • 55. AAL Type 1     Constant-bit-rate source SAR simply packs bits into cells and unpacks them at destination One-octet header contains 3-bit SC field to provide an 8-cell frame structure No CS PDU since CS sublayer primarily for clocking and synchronization 55
  • 56. AAL Type 3/4  May be connectionless or connection oriented  May be message mode or streaming mode 56
  • 57. 57
  • 58. Figure 5.12 Chapter 2 Protocols and the TCP/IP Suite 58
  • 59. AAL Type 5  Streamlined transport for connection oriented protocols  Reduce protocol processing overhead  Reduce transmission overhead  Ensure adaptability to existing transport protocols 59
  • 60. Figure 5.13 Chapter 2 Protocols and the TCP/IP Suite 60
  • 61. 61
  • 62. Emergence of High-Speed LANs  2 Significant trends  Computing power of PCs continues to grow rapidly  Network computing  Examples of requirements  Centralized server farms  Power workgroups  High-speed local backbone 62
  • 63. Classical Ethernet     Bus topology LAN 10 Mbps CSMA/CD medium access control protocol 2 problems: A transmission from any station can be received by all stations  How to regulate transmission 63
  • 64. Solution to First Problem  Data transmitted in blocks called frames:  User data  Frame header containing unique address of destination station 64
  • 65. Figure 6.1 Chapter 6 High-Speed LANs 65
  • 66. CSMA/CD  Carrier Sense Multiple Access/ Carrier Detection  If the medium is idle, transmit. If the medium is busy, continue to listen until the channel is idle, then transmit immediately. If a collision is detected during transmission, immediately cease transmitting. After a collision, wait a random amount of time, then attempt to transmit again (repeat from step 1).    66
  • 67. Figure 6.2 Chapter 6 High-Speed LANs 67
  • 68. Figure 6.3 Chapter 6 High-Speed LANs 68
  • 69. Medium Options at 10Mbps    <data rate> <signaling method> <max length> 10Base5  10 Mbps  50-ohm coaxial cable bus  Maximum segment length 500 meters 10Base-T  Twisted pair, maximum length 100 meters  Star topology (hub or multipoint repeater at central point)‫‏‬ 69
  • 70. Figure 6.4 Chapter 6 High-Speed LANs 70
  • 71. Hubs and Switches       Hub Transmission from a station received by central hub and retransmitted on all outgoing lines Only one transmission at a time Layer 2 Switch Incoming frame switched to one outgoing line Many transmissions at same time 71
  • 72. Figure 6.5 Chapter 6 High-Speed LANs 72
  • 73. Bridge    Frame handling done in software Analyze and forward one frame at a time Store-and-forward Layer 2 Switch    Frame handling done in hardware Multiple data paths and can handle multiple frames at a time Can do cut-through 73
  • 74. Layer 2 Switches      Flat address space Broadcast storm Only one path between any 2 devices Solution 1: subnetworks connected by routers Solution 2: layer 3 switching, packetforwarding logic in hardware 74
  • 75. Figure 6.6 Chapter 6 High-Speed LANs 75
  • 76. Figure 6.7 Chapter 6 High-Speed LANs 76
  • 77. Figure 6.8 Chapter 6 High-Speed LANs 77
  • 78. Figure 6.9 Chapter 6 High-Speed LANs 78
  • 79. Figure 6.10 Chapter 6 High-Speed LANs 79
  • 80. Figure 6.11 Chapter 6 High-Speed LANs 80
  • 81. Benefits of 10 Gbps Ethernet over ATM     No expensive, bandwidth consuming conversion between Ethernet packets and ATM cells Network is Ethernet, end to end IP plus Ethernet offers QoS and traffic policing capabilities approach that of ATM Wide variety of standard optical interfaces for 10 Gbps Ethernet 81
  • 82. Fibre Channel  2 methods of communication with processor:  I/O channel  Network communications  Fibre channel combines both  Simplicity and speed of channel communications  Flexibility and interconnectivity of network communications 82
  • 83. Figure 6.12 Chapter 6 High-Speed LANs 83
  • 84. I/O channel      Hardware based, high-speed, short distance Direct point-to-point or multipoint communications link Data type qualifiers for routing payload Link-level constructs for individual I/O operations Protocol specific specifications to support e.g. SCSI 84
  • 85. Fibre Channel Network-Oriented Facilities    Full multiplexing between multiple destinations Peer-to-peer connectivity between any pair of ports Internetworking with other connection technologies 85
  • 86. Fibre Channel Requirements          Full duplex links with 2 fibres/link 100 Mbps – 800 Mbps Distances up to 10 km Small connectors high-capacity Greater connectivity than existing multidrop channels Broad availability Support for multiple cost/performance levels Support for multiple existing interface command sets 86
  • 87. Figure 6.13 Chapter 6 High-Speed LANs 87
  • 88. Fibre Channel Protocol Architecture      FC-0 Physical Media FC-1 Transmission Protocol FC-2 Framing Protocol FC-3 Common Services FC-4 Mapping 88
  • 89. Wireless LAN Requirements           Throughput Number of nodes Connection to backbone Service area Battery power consumption Transmission robustness and security Collocated network operation License-free operation Handoff/roaming Dynamic configuration 89
  • 90. Figure 6.14 Chapter 6 High-Speed LANs 90
  • 91. IEEE 802.11 Services      Association Reassociation Disassociation Authentication Privacy 91
  • 92. Figure 6.15 Chapter 6 High-Speed LANs 92
  • 93. Figure 6.16 Chapter 6 High-Speed LANs 93
  • 94. Questions ? 94