1

The Design of Offline Scheduling Mechanisms on EPON

Professor : Ho-Ting Wu Student : Pei-Hwa Yin

2

Outline

Back ground review

DBA introduction

Simulation work so far

Remaining work

Q&A

3

Background Review

4

PON’s origination

Bandwidth bottleneck between end users and

backbone networks

PON can provide more bandwidth to end users

in a cost-effective way

5

EPON’s advantages

low-cost Ethernet equipment and low cost passive

optical components

lower cost for equipment maintenance

larger bandwidth capacity

longer transmission distance(10~20km)

6

EPON Architecture

point-to-multipoint fiber optical network with no

active elements in the transmission path from

source to destination

7

Operation principle

In an EPON system all data are encapsulated in

Ethernet packets for transmission

ONU)(OLT- direction Downstream

8

Operation principle

ONU)(OLT- direction Upstream

9

Multi-Point Control Protocol(MPCP)

Being developed by the IEEE 802.3ah task force.

This protocol relies on two Ethernet messages : GATE and

REPORT to achieve dynamic bandwidth allocation process

GATE : assign time slot

REPORT : report ONU’s local queues condition

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Dynamic Bandwidth Allocation (DBA)Mechanism

Online scheduling

Offline scheduling

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Online scheduling

Stop and poll polling policy

12

Interleaved Polling with Adaptive Cycle Time(IPACT)

IPACT mechanism concept

13

IPACT example

14

IPACT example

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IPACT example

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Transmission window

OLT use transmission window to notify ONU let ONU

knows that how many data it can upload in a cycle.

Max transmission window size

It’s a threshold that use to forbid ONU upload too

many data in a cycle

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Transmission window The way to determine the Transmission window size

Limited service

If (request>Transmission window size)

Transmission window size=Max transmission window size

else

Transmission window size=request Gated service

Transmission window size=requestFixed service

Transmission window size=Max Transmission window size

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Offline schedulingOnce OLT collect Report message from all ONUs, then

start to send Gate messages to response ONU.

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Offline scheduling Partial ONU in two groups

High load and light load

Let ONUs which belong the high load group can use excess bandwidth to transmit more data

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Offline schedulingGuarantee bandwidth computation

Excess bandwidth assignment

After DBA Bandwidth assignment

8**

NRGNTB UMAX

MIN

iMIN

L

iiMIN

TOTALEXCESS RBwhereRBB )(

MINiTOTALEXCESSH

ii

iEXCESSi BRifB

R

RB

*

MINiEXCESSiMIN

gi

MINiigi

BRifBBB

or

BRifRB

21

Offline scheduling with early allocation scheme

if (Request<=guarantee bandwidth) Grant bandwidth right away else Grant bandwidth after collect all REPORT messages

22

Simulation work

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Simulation description

Model1(M1) Offline scheduling mechanism

Model2(M2) Offline scheduling with early allocation scheme

Intra-ONU bandwidth assign methods[1]

Strict Priority Priority queuing(OLT)Central control

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Simulation parametersONU number 16Uplink transmission rate 1Gb/sSimulation time 30s

RTT time /transmission distance Uniform(100~200)us /10~20km Offered network load(ONU’s maximum input traffic rate)

0.08~1.6(Gbps)(100Mb/s)

Maximum cycle time 2ms

Guard time 5usPacket size P0 : fix at 70 bytes

P1 , P2 : Uniform(64~1518) bytesTraffic type_1 P0 fix at 4.48Mbit/s，

P1,P2 : Remain loading*50% Packet generate method P0 : Constant bit rate

P1 , P2 : Poisson distribution Measurement metrics Delay

Maximum transmission window size 15000 bytes

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Simulation result

260.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

M1-PriortyQ

M1-PriorityQ-P0 M1-Priority-P1 M1-PriorityQ-P2

Offered network load (Gbps)

Delay(Second)

270.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

1E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

IPACT-limit-PriorityQ

IPACT-limit-PriorityQ-P0 IPACT-limit-PriorityQ-P1 IPACT-limit-PriorityQ-P2

Offered network load (Gbps)

Delay (Second)

280.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

Compare Online to Offine-P0 data

M1-PriorityQ-P0 IPACT-limited-PriorityQ-P0

Offered network load (Gbps)

Delay(Second)

290.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

3.5E-03

4.0E-03

Compare Online to Offine-P1 data

M1-PriorityQ-P1 IPACT-limited-PriorityQ-P1

Offered network load (Gbps)

Delay(Second)

300.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

1E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

Compare Online to Offine-P2 data

M1-PriorityQ-P2 IPACT-limited-PriorityQ-P2

Offered network load (Gbps)

Delay(Second)

310.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

3.5E-03

M1 with different Intra-ONU bandwidth assign methods-P0

Strict Priority-P0 PriorityQ-P0 Central control-P0

Offered network load (Gbps)

Delay(Second)

320.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

3.5E-03

4.0E-03

4.5E-03

M1 with different Intra-ONU bandwidth assign methods-P1

Strict Priority-P1 PriorityQ-P1 Central control-P1

Offered network load (Gbps)

Delay(Second)

330.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

1E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02

M1 with different Intra-ONU bandwidth assign methods-P1

Strict Priorty-P2 PriorityQ-P2 Cental control-P2

Offered network ;oad (Gbps)

Delay(Second)

340.08

0.16

0.24

0.32

0.4

0.48

0.56

0.64

0.72

0.8

0.88

0.96

1 1.04

1.12

1.2

1.28

1.36

1.44

1.52

1.6

0.0E+00

5.0E-04

1.0E-03

1.5E-03

2.0E-03

2.5E-03

3.0E-03

3.5E-03

4.0E-03

Compare M1 M2-PriorityQ-P0,P1

M1-PriorityQ-P0 M2-PriorityQ-P0 M1-PriorityQ-P1 M2-PriorityQ-P0

Offered network load (Gbps)

Delay(Second)

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0.08 0.16 0.24 0.32 0.4 0.48 0.56 0.64 0.72 0.8 0.88 0.96 1 1.04 1.12 1.2 1.28 1.36 1.44 1.52 1.61E-04

1E-03

1E-02

1E-01

1E+00

1E+01

1E+02Compare M1 M2-PriorityQ-P2

M1-PriorityQ-P2 M2-PriorityQ-P2

Offered network load (Gbps)

Delay(Second)

36

Remaining work

Define a DBA which base on offline scheduling that can well reduce idle time on EPON system.

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Reference[1] C.M. Assi, Yinghua Ye, Sudhir Dixit, and M.A. Ali, “ Dynamic

bandwidth allocation for quality-of-service over Ethernet

PONs ,”IEEE Journal on Selected Areas in Communications,

vol.21, no.9, pp. 1467-1477, November 2003.

[2] G. Kramer, B. Mukherjee, and G. Pesavento, “Interleaved Polling

with Adaptive Cycle Time (IPACT): A Dynamic Bandwidth

Distribution Scheme in an Optical Access Network,”Photonic

Network Communications, vol. 4, no. 1 pp. 89-107, January 2002.

[3] J. Zheng and H.T. Mouftah, “Media access control for Ethernet

passive optical networks: an overview,”IEEE Communications

Maganize, vol.43, no2 pp.145-150 , February 2005.

[4] G. Kramer, Ethernet Passive Optical Networks, McGraw-Hill

Professional, ISBN: 0071445625, Publication date: March 2005.

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Q&A