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Outlines Received due 13 March 2000

Outlines Received due 13 March 2000. 24 %. Homework. Review for Midterm (1 March 2000) Research Paper Readings [9] “MPLS: Special Delivery” [10] “Diversifying Internet Delivery”. Frame Relay. ANSI Standard covering OSI Layer 2 Accessed by Routers or FRAD’s

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Outlines Received due 13 March 2000

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  1. OutlinesReceiveddue 13 March 2000 24 %

  2. Homework • Review for Midterm (1 March 2000) • Research Paper • Readings[9] “MPLS: Special Delivery”[10] “Diversifying Internet Delivery”

  3. Frame Relay • ANSI Standard covering OSI Layer 2 • Accessed by Routers or FRAD’s • Derived from X.25 Protocol Dumps almost all error checking Requires fiber on the long haul • Uses Permanent Virtual Circuits (PVC’s) VC differs from Datagram Long Term Connection Requires Carrier intervention to change

  4. Frame Relay • Committed Information Rate (CIR) Is a Quality of Service Guarantee ‘Guaranteed’ minimum Bandwidth Should be set > average traffic during appropriate peak period • Port Connection Speed a.k.a. Port Speed or Burst Speed Bandwidth you can burst to provided network capacity exists.

  5. Ex) 1.54 Mbps Leased Lines Detroit Leased Line IXC Leased Line Network OKC NYC IXC & Local Carriers dedicate 1.54 Mbps to our use via Circuit Switching & TDM. Router

  6. Carrier Leased Line Network Trunks Leased Line Cross-Connect Leased Line ‘Cloud’ Trunks use TDM & Circuit Switching

  7. Ex) Frame Relay Detroit PVC, OKC - Detroit IXC Frame Relay Network OKC PVC, NYC - OKC NYC Router Local Carriers dedicate 1.54 Mbps to our use. IXC provides random Packet Switched StatMux connectivity via PVC’s.

  8. Frame Relay Backbone Trunks Leased Line FR Switch Frame Relay ‘Cloud’ Trunks use StatMux & Packet Switching

  9. Ex) Internet Detroit ISP Network OKC NYC Router Local Carriers dedicate 1.54 Mbps to our use. ISP provides random Packet Switched StatMux connectivity via datagrams.

  10. Internet Service Provider Backbone Trunks Leased Line Router ISP ‘Cloud’ Trunks use StatMux & Packet Switching

  11. WAN Design (Link Reduction) • Start with Traffic Matrix • Examine Full Mesh • Consider eliminating lightly used links • Compare costs at each iteration

  12. Circuit Switched connections waste bandwidth for bursty traffic. traffic NYC to OKC 1.54 Mbps Line Speed 146 Kbps Average time Idle Time >> Active Time

  13. Frame Relay • End-to-End DelayFrame Relay > equivalent sized Leased Line Network • Cost TendencyFrame Relay < equivalent sized Leased Line Network

  14. Frame Relay (Inside the Cloud) • Examined a specific case Frame Relay Switch 100 Mbps Trunk ?? 1.54 Mbps Connections P(Access Line is Active) = 10% How many access lines can this switch support?

  15. Bounds on Packet Switch Carrying Capacity 100 Mbps Trunk, 1.54 Mbps Inputs with 154 Kbps average loads Lower Upper90% 559 64999% 494 64999.9% 452 64999.99% 421 649 Availability Where switch probably operates Where switch could operate

  16. Given 100 Mbps of Bandwidth... • 64 1.54 Mbps Circuit Switched TDM Customers • 421 - 649 1.54 Mbps Packet Switched StatMux Customers with 154 Kbps average load & 99.99% availability More Bursty Data Traffic can be moved with the Packet Switched StatMux network.

  17. Network Cost... • Can be spread over 64 Leased Line customers • Can be spread over 421 Frame Relay customers • Frame Relay & the Internet Are Packet Switched StatMux network Largely hauling bursty data traffic Effectively haul bursty data traffic Inexpensive (compared to a Leased Line)

  18. Switched Network Carrying Capacities Carrying Capacity Packet Switch StatMux Circuit Switch TDM 0% Data 100% Data 100% TST 0% TST Offered Load

  19. Voice Over Frame Relay • Many of same problems as Voice over IP Designed for data One Priority • Quality is worse than Telephone System • Quality is better than Internet Voice CIR guarantees Bandwidth FRAD can prioritize voice • Video over FR products now available

  20. Priorities are a double edged sword... • There is only so much pie to go around Frame Relay Switch 100 Mbps Trunk Hi Priority Voice PVC’sLo Priority Data PVC’s If voice gets preference, data will suffer!

  21. QoS • DE bit used by FR switches to police network • Traffic > CIR enters switch in a 1 second interval? Marked DE • If you are behaving......and other users exceed their CIR’s......and FR switch becomes congested......then other users’ traffic gets dumped 1st......your traffic is protected. • Helps shelter you from behavior of others

  22. Internet Performance Probability of dropped packets Average Delay for delivered packets 0% 100% Trunk Offered Load

  23. Frame Relay Performance Probability of dropped packets* Average Delay for delivered packets 0% 100% Trunk Offered Load *Dashed: If we are transmitting at > CIR Solid: Provided we are transmitting at < CIR

  24. Worldwide Frame Relay Revenues Source: Data Communications $9.45B ‘99 $6.25B ‘98 $0.08B ‘93 $0.65B ‘95 $3.87B ‘97 $0.23B ‘94 $1.28B ‘96

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