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Minimize. Discovery Collision Probability. in. EPON. Group meeting 12.29. Advisor : Guo wei Liu zhe. Overview. Background - 802.3ah & EPON Project Description Project status and advancement plan. Project Background. Downstream Model. Data in true Ethernet frames. Upstream Model.

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  1. Minimize Discovery Collision Probability in EPON Group meeting 12.29 Advisor: Guowei Liu zhe

  2. Overview • Background - 802.3ah & EPON • Project Description • Project status and advancement plan

  3. Project Background

  4. Downstream Model Data in true Ethernet frames

  5. Upstream Model • TDMA • No collisions • No fragmentation

  6. Dicovery process in ONU & OLT • Gate,Regsiter_req,Register,Register_ack,

  7. Round-trip time measurement in Auto discovery • RTT = t2 – t1

  8. Discovery slot and discovery window RTT max = 2 * 20km/2e8 = 200us

  9. Frame overhead • IFG(inter frame guarding) 8Bytes • AGC(auto gain control) 400ns • CDR(clock data recovery)400ns • Ethernet Frame overhead 8+6+6+4+2=26Bytes • Laser on 512ns • Laser off 512ns total overhead = 2096ns = 2.096us

  10. The Project

  11. Project Goal • Design and analyze discovery cycle policy • Create an EPON simulation in OPNET • For future: WDM-EPON DBA & double OLT WDM-EPON simulation Design and test discovery cycle policy for minimizing collision probability and enhance user experience

  12. Test Scenario

  13. OPNET Prototype Goal: Construct a basic OPNET model of EPON Main Features: • Add 802.3ah packet formats (new MAC messages) • TDMA bandwidth allocation scheme • ONU • Filter GATE messages and act upon them • Generate REPORT messages based on queue status • OLT • Collect reports from all ONUs • Ability to generate GATE messages • Basic statistics gathering

  14. ONU Data Path Register_req Register_ack Report To PON Grant & Register From PON 1 Gbps ONU Traffic ONU Data

  15. Packet_filter_process • The red state: unforced state, the system can stay here • The green state: forced state. Do and leave now

  16. ONU_scheduler_process Generate Status Regis_req Future control msgs Generate Status Report Generate Status Regis_ack

  17. OLT Data Path To PON Gate Register Register_req Register_ack Report From PON 1 Gbps Upstream Data

  18. Packet Format Register Register_ACK

  19. The Presentation Ends The Work Continues…

  20. Thank You! Happy New Year

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