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The Design of power saving mechanisms in Ethernet Passive Optical Networks

Yun-Ting ChiangAdvisor: Prof Dr. Ho-Ting Wu

2013.10.28

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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

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Passive Optical Network (PON)

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Passive Optical Network (PON)

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

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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)

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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

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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

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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.

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Early wake up

ONU can receive GATE

msg

Because of Toverhead , ONU have wait 2.125ms to receive GATE msg. from OLT

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Lei Shi, Biswanath Mukherjee and Sang-Soo Lee’s research

Didn’t consider downstream high priority data delay

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Add doze mode in ONU

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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.

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Add doze mode in ONU

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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.

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Improve three energy-modes in ONU

Clockwise three energy-modes switching Counterclockwise three energy-modes switching

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Clockwise three energy-modes switching

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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.

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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.

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Counterclockwise three energy-modes switching

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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.

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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 upp.s.Active mode trigger: If report msg. request bandwidth = 0, means no upstream data.

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Upstream scheduling Using Limited service. Limited service : OLT grants requested number of

bytes, but no more than MTW OLT polling table increase ONU state.

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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.

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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 * 10-6

Y : After 20ms the state from sleep to doze Z : After 30ms the state from doze to active Simulation time 3s

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

0.8 1.6 2.4 3.2 4 4.8 5.6 6.4 7.2 8 8.8 9.6 10.4 11.2 12 12.8 13.6 14.4 15.6 160

0.2

0.4

0.6

0.8

1

1.2

ActiveDozeSleep

Downstream load

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

0.8 1.6 2.4 3.2 4 4.8 5.6 6.4 7.2 8 8.8 9.6 10.4 11.2 12 12.8 13.6 14.4 15.6 160

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0.2

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0.8

0.9

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ActiveDozeSleep

Downstream load

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

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.975 10

0.1

0.2

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0.9

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ActiveDozeSleep

Upstream load

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

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.975 10

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ActiveDozeSleep

upstream load

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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.

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Reference

[1] Glen Kramer and Biswanath Mukherjee “IPACT: A Dynamic Protocol for an Ethernet PON (EPON),” IEEE Communications Magazine, February 2002.

[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. 36-41.

[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. s34-38.

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Thanks for your listening