The Design of power saving mechanisms in Ethernet Passive Optical Networks Yun-Ting Chiang Advisor: Prof Dr. Ho-Ting Wu

Outline  Introduction  Optical-Fiber Network  Passive Optical Network (PON)  EPON Interleaved Polling with Adaptive Cycle Time (IPACT)  The Design of Power Saving mechanisms in Ethernet Passive Optical Networks  Two energy-modes in ONU  Add doze mode in ONU  Improve three energy-modes in ONU Clockwise three energy-modes switching Counterclockwise three energy-modes switching Upstream scheduling Downstream scheduling  Simulation result  Conclusion 2

Passive Optical Network (PON) 3

 Optical line terminal (OLT)  Optical network units (ONUs) or Optical network terminals (ONTs)  Use broadcast on Downstream  Use TDMA on Upstream  All ONUs register to OLT with LLID 4

EPON  REPORT and GATE message  REPORT  ONU to report its bandwidth requirements  OLT passes REPORT to the DBA algorithm  GATE  After executing DBA algorithm, OLT transmits GATE down-stream to issue up to four transmission grants to ONU  Transmission start time  Transmission length  Timestamp (used by ONU for synchronization) 5

Interleaved Polling with Adaptive Cycle Time (IPACT)  OLT maintain a Table with Byte and RTT  First grant, G(1), is set to some arbitrary value  In polling cycle n, ONU measures its backlog in bytes at end of current upstream data transmission & piggybacks the reported queue size, Q(n), at end of G(n)  Q(n) used by OLT to determine next grant G(n+1) => adaptive cycle time & dynamic bandwidth allocation  If Q(n)=0, OLT issues zero-byte grant to let ONU report its backlog for next grant 6

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The Design of Power Saving mechanisms in Ethernet Passive Optical Networks  Two energy-modes in ONU  Add doze mode in ONU  Improve three energy-modes in ONU 8

Two energy-modes in ONU  In L. Shi, B. Mukherjee, and S. S. Lee, "Efficient PON with Sleep-Mode ONU: Progress, Challenges, and Solutions," refer two energy-modes including active and sleep modes. They separate high/low priority packet. 9

Early wake up 10 Because of T overhead, ONU have wait 2.125ms to receive GATE msg. from OLT

Lei Shi, Biswanath Mukherjee and Sang- Soo Lee’s research  Didn’t consider downstream high priority data delay 11

Add doze mode in ONU 12

Add doze mode in ONU  ONU Tx: off Rx:on  Downstream high priority data won’t trigger sleep ONU wake.  Doze mode can make OLT send downstream data earlier. 13

Add doze mode in ONU 14

Add doze mode in ONU : Weak point  Doze mode will implement even no downstream data.  Low doze mode utilization  Active mode can’t turn to doze mode when no downstream data. 15

Improve three energy-modes in ONU 16  Clockwise three energy-modes switching  Counterclockwise three energy-modes switching

Clockwise three energy-modes switching 17

Clockwise three energy-modes switching Consider performance A -> S [1] No upstream and downstream data when OLT get ONUx’s REPORT. A -> D [2] No upstream data but has downstream data when OLT get ONUx’s REPORT. S -> A [3] Upstream high priority data coming // Early wake up S -> D [4] Stay at sleep mode for consecutive Y clock // variable Y protects downstream high priority data ， Y is maximum of downstream high priority data delay. 18

Clockwise three energy-modes switching D -> A [5] Stay at doze mode for consecutive Z clock || upstream high priority data coming // Timer avoids upstream long low priority data delay // variable Y 、 Z protects upstream low priority data ， Y + Z is maximum upstream low priority data delay p.s. Active mode trigger: If report msg. request bandwidth = 0, means no upstream data. 19

Counterclockwise three energy-modes switching 20

Counterclockwise three energy-modes switching Consider power saving A -> S [1] No upstream and downstream data when OLT get ONUx’s REPORT. A -> D [2] No upstream data but has downstream data when OLT get ONUx’s REPORT S -> A [3] Stay at sleep mode for Y clock || upstream high priority data coming // variable Y protects downstream high priority data ， Y is maximum of downstream high priority data delay. 21

Counterclockwise three energy-modes switching D -> S [4] Stay at doze mode for consecutive Z ms // Force // Timer avoids upstream long low priority data delay // variable Y 、 Z protects upstream low priority data ， Y + Z is maximum upstream low priority data delay // Switch from Doze mode to Sleep mode is no delay so downstream high priority data increase Y clock delay, it’s maximum of downstream high priority data delay D -> A [5] upstream high priority data coming // early wake up p.s. Active mode trigger: If report msg. request bandwidth = 0, means no upstream data. 22

Upstream scheduling  Using Limited service.  Limited service : OLT grants requested number of bytes, but no more than MTW  OLT polling table increase ONU state. 23

Downstream scheduling  Although downstream slot and upstream slot are difference but there have some relationship.  Different from general EPON, because ONU[x] in sleep mode, OLT can’t send downstream data. Downstream scheduling need to be considered.  ONUs’ doze mode maybe overlap so OLT need to select one of ONUs to send downstream data. 24

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Simulation Result  Clockwise three energy-modes switching  ONU = 16  ONU queue size 10MByte  EPON Frame size = 64Bytes ~ 1518 Bytes  Channel capacity = 1Gbps  Max rate = 100 * 1000 * 1000 = 100Mbps  Guard time = 5 *  Y : After 20ms the state from sleep to doze  Z : After 30ms the state from doze to active  Simulation time 3s 26

Dynamic downstream loading  Upstream load:1 High = 99% Low = 1% 27

Dynamic downstream loading  Upstream load:0.01 High = 50% low = 50% 28

Dynamic upstream loading  Downstream load = 10 High = 99% low = 1% 29

Dynamic upstream loading  Downstream load: 0.01 High = 50% low = 50% 30

Conclusion  In this study, power saving mechanisms focus on reduce high priority downstream data delay in power saving EPON.  In order to raise up doze mode utilization, we design new three energy-modes switching mechanisms to increase it.  All results discuss between power saving and performance, it’s trade off. Maybe we can improve traffic scheduling or switching mechanism for future. 31

Reference [1] Glen Kramer and Biswanath Mukherjee “IPACT: A Dynamic Protocol for an Ethernet PON (EPON),” IEEE Communications Magazine, February [2] Lei Shi, Biswanath Mukherjee and Sang-Soo Lee “Energy-Efficient PON with Sleep-Mode ONU: Progress, Challenges, and Solutions,” IEEE Network March/April 2012 pp [3] Jingjing Zhang and Nirwan Ansari “Toward Energy-Efficient 1G- EPON and 10G-EPON with Sleep-Aware MAC Control and Scheduling,” IEEE Communications Magazine February 2011 pp. s

Thanks for your listening 33