GPON 光學網路上動態頻寬配置機制的設計

指導教授：吳和庭老師

Speaker ：蘇泳蒼

1

OutlineIntroductionGPON DBASimulationFuture workReferences

2

Introduction

3

ONU 1

ONU 2

ONU N

OLT......

Introduction在 GPON ，上傳頻寬分配是用 T-CONT

(transmission container) 來做分配的， T-CONT是一群連接，且每一個 T-CONT 都會對到一個Alloc-ID 。

OLT 會利用 BWmap (upstream bandwidth map) 來指示 ONU 何時可以傳送資料。

4

ITU-T dynamic bandwidth assignment每個 Alloc-ID 都會有 traffic descriptor 來描述頻

寬分配的參數

RF : Fixed bandwidth

RA : Assured bandwidth

RM : Maximum bandwidth

χAB : Ternary eligibility indicator for additional bandwidth assignment {None, NA, BE}

iAB

iM

iA

iF

i RRRD ,,,

5

ITU-T dynamic bandwidth assignment分配給 Alloc-ID 的頻寬可以分成兩個部分，分別是

guaranteed 和 additionalχAB = NA

χAB = BE

RG : Guaranteed bandwidth

RNA : Non-assured bandwidth

RBE : Best-effort bandwidth

)()()( tRtRtR iNA

iG

i

)()()( tRtRtR iBE

iG

i

6

ITU-T dynamic bandwidth assignment Guaranteed bandwidth 的分配方式是

RL : Offered traffic load

分配完 guaranteed bandwidth 之後剩下的頻寬，就分配給 non-assured bandwidth

對於任兩個要求沒被滿足的 Alloc-ID ，分配方式如下

)(;max;min)( tRRRRtR iL

iF

iA

iF

iG

7

jA

jF

jNA

iA

iF

iNA

RR

tR

RR

tR

)()(

ITU-T dynamic bandwidth assignment 分配完 non-assured bandwidth 之後剩下的頻寬，接

著分配給 Best-effort bandwidth 對於任兩個要求沒被滿足的 Alloc-ID ，分配方式如下

)(

)(

)(

)(jA

jF

jM

jBE

iA

iF

iM

iBE

RRR

tR

RRR

tR

8

ITU-T dynamic bandwidth assignment T-CONT type 1 is suitable for carrying fixed-rate

traffic which is sensitive to delay and jitter. T-CONT type 2 is suitable for carrying on-off type

traffic with well-defined rate bound which does not have strict delay and jitter requirements.

T-CONT type 3 is suitable for carrying variable-rate bursty traffic which requires average rate guarantee.

T-CONT type 4 is suitable for carrying variable-rate bursty traffic which does not exhibit delay sensitivity.

T-CONT type 5 is a consolidation of other T-CONT types which can be applied to most general traffic flows.

9

ITU-T dynamic bandwidth assignment

Traffic descriptorcomponen

t

Type 1 Type 2 Type 3 Type 4 Type 5

Fixed BW RF RF

Assured BW RA RA RA

Maximum BW

RM = RF RM = RA RM > RA RM

RM ≥ RF + RA

Additional BW

eligibilityNone None NA BE Any

10

Immediate allocation with colorless grant algorithm

T-CONT type Bandwidth Service parameters

1 Fixed SImax , ABmin

2 Assured SImax , ABmin

3Assured SImax , ABmin

Surplus SImin , ABsur

4For polling SImax , ABmin

Surplus SImin , ABsur

11

Immediate allocation with colorless grant algorithm

12

配置頻寬Va(j) > 0

SImax_timer(j) = 1

SImax_timer(j)=SImax(j)

Va(j) = ABmin(j)

SImax_timer(j)--

是

否

是

否

Immediate allocation with colorless grant algorithm

配置頻寬Vs(j) > 0

SImin_timer(j) = 1

SImin_timer(j)=SImin(j)

Vs(j) = ABsur(j)

SImin_timer(j)--

是

否

是

否

Immediate allocation with colorless grant algorithm從 Alloc-ID 的頻寬需求、 Va 、剩下的頻寬中取最

小值，然後將此值作為分配給 Alloc-ID 的頻寬

將 Va 減掉分配給 Alloc-ID 的頻寬大小

Immediate allocation with colorless grant algorithm若還有多餘的頻寬，則將多餘的頻寬平均分配給各

各 ONU 的 T-CONT type 5ONU 將會依 T-CONT type2 、 type3 、 type4 的

順序，來傳送 queue 裡的資料，直到頻寬被用盡或是 queue 裡都沒資料

Simulation模擬工具： OMNeT++T-CONT type 1 traffic 類型：每 125 us 來 50

bytes packetT-CONT type 2 、 3 、 4 traffic 類型： PoissonT-CONT type 2 、 3 、 4 traffic 比例：為扣除 T-

CONT type 1 之後，平均分配Packet size ： 64 ~ 1518 bytes模擬時間： 10 sec

16

Simulation

17

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.0001

0.0002

0.0003

0.0004

0.0005

0.0006

0.0007

0.0008

0.0009

IACG type1IACG type2IACG type3IACG type4ITU-T type1ITU-T type2ITU-T type3ITU-T type4

Traffic load

Dela

y (

s)

Simulation

18

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.2

0.4

0.6

0.8

1

1.2

IACGITU-T

Traffic load

Uti

lizati

on

Future work研究在其他 traffic 的狀況下， DBA 的運作情形探討在 long reach 的情況下， DBA 是否能運作良

好設計更有效率的 DBA

19

References ITU-T Rec. G.984.1, “Gigabit-capable Passive Optical

Networks (G-PON): General characteristics,” 2008. ITU-T Rec. G.984.3, “Gigabit-capable Passive Optical

Networks (G-PON): Transmission convergence layer specification,” 2008.

M.S. Han, H.Y., B.Y. Yoon, B. Kim and J.S. Koh, “Efficient dynamic bandwidth allocation for FSAN-compliant GPON,” Journal of Optical Networking, Vol. 7, Issue 8, 2008, pp. 783-795.

20

Q&A

Thanks for you attention

21