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WAN

WAN. Wide Area Networks. Review:. Capacity Allocation: phone system Bandwidth Allocation: data systems. Network. WAN Access. WAN. Intercommunication over public networks Typically slower and more expensive than backbone or LAN. Connections. Connection Oriented Circuits

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WAN

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  1. WAN Wide Area Networks

  2. Review: • Capacity Allocation: phone system • Bandwidth Allocation: data systems

  3. Network WAN Access

  4. WAN • Intercommunication over public networks • Typically slower and more expensive than backbone or LAN

  5. Connections • Connection Oriented Circuits Have a mechanism to confirm delivery and assure that packets are processed in order • Circuits • Packet Assembly Devices • Non-Connection Oriented Circuits • Deliver packets individually without regard to message sequence

  6. Wan Resources • Bandwidth • Access • Technology

  7. Bandwidth Total transport capacity

  8. North American Digital Hierarchy • T0 56 + 8 Kbps 64 Kbps • T1 1.544 Mbps 24xT0 • T2 6.312 Mbps 96xT0 • T3 44.736 Mbps 672xT0 • T4 274.176 Mbps 4032xT0

  9. Multiplexing and Wide Area Communication MUX VOICE STREAM WAN LINK

  10. Multiplexing and Wide Area Communication MUX DATA STREAM A DATA STREAM B WAN LINK

  11. Node Functions • Message forwarding • Error detection and correction • Traffic management

  12. CSU/DSU:Digital Service Unit/Channel Service Unit

  13. Access Methods of controlling the WAN traffic

  14. Traffic Management • Access Control • Buffering • Packet Discard

  15. Circuits vs Packets Circuits Switched • path • setup and teardown Permanent Packets datagram

  16. Switches • Cut-through switch • Store-and-forward switch

  17. Switches (Store & Forward) From A H Input Buffer Proces- sor H Output Buffer Input Buffer Output Buffer H Input Buffer Table of Addresses To D

  18. Routers From A From B Input Buffer Output Buffer Proces- sor Input Buffer Output Buffer Input Buffer Table of Addresses To C To D

  19. Router Functions Layer 1, 2, and 3 functions • Packet passing • Error correction • Message routing • Including circuit definition • Protocol translation • Firewall functions

  20. Source Destination Setup Message & ACK’s Teardown Circuit Logic

  21. Datagram Logic Packet n Packet 2 Packet 1

  22. Technologies Common WAN technologies.

  23. X.25 • Older protocol for using packet switched data • Operates up to 56.6 Kbps • Switched virtual circuit • PAD

  24. TCP/IP • Best Effort • Addressing • IPv4 vs IPv6 • Frame and Header

  25. TCP/IP

  26. OSI and TCP/IP OSI TCP/IP 7. Application 6. Presentation Process & Application 5. Session 4. Transport Host to host (TCP) 3. Network Internet (IP) 2. Data link Network access 1. Physical

  27. Datagram Routing • Best effort • Error Control • Traffic Management

  28. IP Header (Layer 3)

  29. TCP Header

  30. IP Addressing • 32 bits (4 bytes) • Network address + • Host address • Classes • A: 126 nets, 3 bytes of client addresses • B: 2 bytes of client addresses (e.g. OU) • C: 1 byte of client addresses (256)

  31. ISDN

  32. Frame Relay • Frames relayed without reconstruction • End to end error control using CRC error detection at layer 3 level • Variable packet size • Virtual circuit (usually permanent) • Multiple data rates • Committed Data Rate • Peak data rate (discard eligible)

  33. ATM

  34. ATM Traffic Classes • Type 1 Constant Bit Rate • Type 2 Variable Bit Rate • Type 3 • Type 4 • Type 5 IP Traffic

  35. ATM

  36. SNA • Connection Oriented • Centrally Managed

  37. WAN Costs • Circuit Charges • Committed Bandwidth • Peak Bandwidth • Discard Priority • Latency

  38. WAN

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