Fair Sharing Using Service-Level Agreements (SLAs) for Open Access in EPON Amitabha Banerjee, Glen...

Fair Sharing Using Service-Level Agreements (SLAs)

for Open Access in EPON

Amitabha Banerjee,

Glen Kramer,

Biswanath Mukherjee

{abanerjee, gkramer, bmukherjee}@ucdavis.edu

ICC 2005, Seoul, South Korea 2

Open Access Network - Illustration

OLT

ONU

ONU

Neutral EPONaccess network

Voice + Video + Internet

SP ASP A

SP BSP B

Voice + Video

SP C

SP C

Video + Conferencing

SP D

SP D

Video + Playstation

SP ESP EVoice + Video + Playstation

End users:FTTx

SP = Service Provider


The Shared Access Channel

• Define an active connection between an SP and a user as a flow.

• Possible approaches to fairness:– Fair sharing between flows.– Fair sharing between users.– Fair sharing between SPs.– Fair sharing between both users and SPs

simultaneously (By having Dual SLAs).


SPa

SPb

U1

U2

U3C = 60 units

U4

Qa1

Qa2

Qa3

Qa4

Queue size(units)

15

15

15

15

15

15U5

Qb4

Qb5

Allocated(units)

10

10

20

10

10

Allocated(units)

10

10

10

10

10

10

40

20

Fair Sharing Between Flows

Equal share to each independent flowe.g. Deficit Round Robin (DRR)

Fair to neither SPs nor Users


SPa

SPb

U1

U2

U3C = 60 units

Allocated(units)

12

12

12

6U4

Qa1

Qa2

Qa3

Qa4

Queue size(units)

15

15

15

15

15

156

12

42

Allocated(units)

12

12

12

12U5

Qb4

Qb5

12

18

Fair Sharing Between Users

Not fair to SPs

Equal share to each User


SPa

SPb

U1

U2

U3C = 60 units

Allocated(units)

7.5

7.5

7.5

7.5U4

Qa1

Qa2

Qa3

Qa4

Queue size(units)

15

15

15

15

15

1515

15

30

Allocated(units)

7.5

7.5

22.5

15U5

Qb4

Qb5

7.5

30

Fair Sharing Between SPs

Equal share to each SP

Not fair to Users


User SLA = 10 units(primary)SP SLA = 25 units(secondary)SPa

SPb

U1

U2

U3C = 60 units

U4

Qa1

Qa2

Qa3

Qa4

Queue size(units)

15

15

15

15

15

15U5

Qb4

Qb5

Allocated(units)

10

10

15

15

10

Allocated(units)

10

10

10

5

10

15

35

25

Fair Sharing Using Dual SLAs

Use Dual SLAs

Objective: To be fair to both SPs and Users


Scheduling Time-slots for Fairness

Time cycle of max duration T

Scheduling Algorithm invoked

Packets transmitted

Next invocation of Scheduling Algorithm.

Time-slot assigned to each flowga1 ga2 gb1 gb2 gc1

Packets arrive


Scheduling Parameters

Global Parameters• R: EPON bit rate• M: # of SPs• N: # of Users• Uj

MIN: User SLA (pri)• Wi

MIN: SP SLA (sec)

Time cycle parametersC = R * T

ujMIN

= UjMIN * T

wiMIN

= WiMIN

* T

T = Maximum duration of time cycle.


Scheduling

• Given– Time t at which scheduler is invoked– qi,j,t: Queue size for queue from SP i to User j

• Determine– ∆: Scheduling time cycle duration– gi,j,t,t+∆: Bandwidth allocated for SP i to User j

• Constraints– Bandwidth allocation constraint, gi,j,t,t+∆ ≤ qi,j,t

– Capacity constraint, Σi Σj gi,j,t,t+ ∆ ≤ C– Maximum scheduling time cycle constraint, Tadv ≤ ∆ ≤ T


Max – Min Fair Bandwidth

• Bandwidth allocation to poorest entity

Q1 Q2 Q3 Q4


Step 3:Allocate grants to meet Primary SLA. If sufficient capacity is not available,

then recover grants assigned in Step 2 to meet deficit.-------------------------------------------------------------------------------------

availBW = C – ΣiΣj gi,j,t,+∆demandUserj = MIN [ uj

MIN, Σiqi,j,t ]

preAssignedUserj = Σigi,j,t,t+ ∆

Assign Max-Min fair BW amongst usersFor all users for which demandUseri not met:

Invoke Algorithm RecoverBW

Is demand < capacity of maximum timeslot ?

--------------------------------------

Is

Σi Σj gi,j,t,t+ ∆ ≤ C ?

Algorithm

Case IIStep 1:Identify mandatory grants.

Step 2:Allocate Grants to meet Secondary SLA

Step 3:Allocate grants to meet Primary SLA. If sufficient capacity is not available, then recover grants assigned in Step 2 to meet deficit.

Step 4:Grant remaining timeslot fairly amongst users.

Is demand < capacity of maximum timeslot ?

Case IAllocate grants equal to demand

Yes No

Start

Case IAllocate grants equal to demand

---------------------------------

1. gi,j,t,t+∆ = qi,j,t

2. ∆ = Max [Tadv, Σi Σj qi,j,t/ R]

Case IIStep 1:

Identify mandatory grants.-------------------------------------

1. User j: Σi qi,j,t < ujMIN

2. User subscribed to single SP

Step 2:Allocate Grants to meet Secondary SLA

------------------------------------------------------

availBW = C – ΣiΣj gi,j,t,+∆

demandSPi = MIN [ wiMIN

, Σjqi,j,t ]preAssignedSPi = Σj gi,j,t,t+ ∆

Assign Max-Min fair BW to SPsSimilarly for each User within SP

Step 4:Grant remaining timeslot fairly amongst users.

---------------------------------------------------------------

Assign Max – Min fair BW to usersSimilarly for SPs for each User


Algorithm Recover Bandwidth

UMIN

deficit

Recover BW from same SP

No change in SP allocations

Recover BW from different SPs

Ui Ui’

gi’,j,t,t+∆

SPj’ Ui’

UMINgi’,j’,t, t+∆

Ui

SP SLA may be violated


OLT

6 SPs

ONU

ONU

16 users

1 Gbps EPON

Simulation Model

SP SLA is 150 Mbps per SP

User SLA is 50 Mbps per User

Traffic is generated to be self-similar with Hurst Parameter of 0.8


Traffic Matrix

Time SPs User Set Traffic Rate

Aggregate Load

0 – 100 s 1 Set I (1 – 9) +

Set II (10 – 12) +

Set III (13 – 14) +

Set IV (15 – 16)

40 Mbps 0.64

20s – 100s 2, 3, and 4

Set II (10 – 12) 50 Mbps 1.09

40s – 100s 5 Set III (13 – 14) 75 Mbps 1.24

60s – 100s 6 Set IV (15 – 16) 75 Mbps 1.39


Results (SPs) – DRR

Throughput to SPs by Deficit Round Robin Sharing

0

100

200

300

400

500

600

700

800

900

1000

0 20 40 60 80 100

Time (seconds)

Thr

ough

put (

Mbp

s )

SP 1

Avg SP 1

SP 2

Avg SP 2

SP 3

Avg SP 3

SP 4

Avg SP 4

SP 5

Avg Sp 5

SP 6

Avg SP 6


Results (SPs) – Dual SLA

Throughput to SPs by Dual SLA Scheduling Algorithm

0

100

200

300

400

500

600

700

800

900

1000

0 20 40 60 80 100Time (seconds)

Thr

ough

put (

Mbp

s )

SP 1

Avg SP 1

SP 2

Avg SP 2

SP 3

Avg SP 3

SP 4

Avg SP 4

SP 5

Avg Sp 5

SP 6

Avg SP 6


Results (Users ) - DRR

Throughput to Users by Deficit Round Robin Sharing

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100

Time (Seconds)

Thr

ough

put (

Mbp

s)

User Set I

Avg User Set I

User Set II

Avg User Set II

User Set III

Avg User Set III

User Set IV

Avg User Set IV


Results (Users) – Dual SLA

Throughput to Users by the Dual SLA Scheduling Algorithm

0

20

40

60

80

100

120

140

160

180

0 20 40 60 80 100

Time (seconds)

Thr

ough

put (

Mbp

s) User Set I

Avg User Set I

User Set II

Avg User Set II

User Set III

Avg User Set III

User Set IV

Avg User Set IV


Conclusion

• Open access requires sharing of bandwidth between both users and SPs.

• The above may be achieved by using the Dual SLA Scheduling Algorithm.

• Dual SLA Scheduling Algorithm has good fairness properties.


Questions ?

• For further details please contact– Amitabha Banerjee at [email protected]– Glen Kramer at [email protected]– Biswanath Mukherjee at [email protected]

Fair Sharing Using Service-Level Agreements (SLAs) for Open Access in EPON Amitabha Banerjee, Glen...

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