Packet Triplet: An Enhanced Packet Pair Probing for Path

Capacity Estimation

Nanyang Technological University Zou ZiXuan

OUTLINE

The purpose of Packet TripletPrevious Packet-Pair based techniquesPacket Triplet probingDetailed approachFiltering schemeExperimental Results

The purpose of Packet Triplet

Measuring the path capacity (bottleneck)Packet-Pair basedRobust to cross traffic

Previous Packet-Pair based technique

Packet-Pair dispersion Originated by Keshav for congestion

control Cross traffic effect—expression and

extension Variants of Packet-Pair to deal with the

effects of cross traffic.

Previous Packet-Pair based technique

Statistical method Sending many packet pairs, using

statistical approach Union and Intersection Kernel density

Do not always lead to correct estimation Not a global modal but the local modal Observed by Paxson, investigated by Dovrolis

Previous Packet-Pair based technique

Model based detection Based on Multimodal distribution Packet-Train and Packet-Pair

Packet-Triplet probing

Deal with multimodal distributionAccurately estimate path capacity in different load traffic Different from model-based detection

Detailed approach

Three back-to-back probing packets and dispersion pair

3 2 1

L LL

3 2 1

recei ver si de

1 2

Sender si de

12

12

21

jj

jj

jjj LBB

11 / LB 22 / LB

Detailed approachPacket Triplet probing

Idea condition No cross traffic

The variation of Latency of probing packets

Equivalent estimates

3 2 1

L LL narrow l i nk i

3 2 1

i i

recei ver si de

02

21

i

iijjj LBB

012

21

jj

iijjj LBB

),( 21jj BB

j

Detailed approachCross traffic effect When

When Narrow link capacity estimates (NLE)

j

3 2

123

1

1j2

j

1j2

j

j

3 2 1

L LL

3 2 1

recei ver si deSender si de

1 i 2 i

narrow l i nk i

ii CL /

21

),( 21jj BB

Cont’d Post-narrow link estimates (PNLE)

Equivalent noise (EN) Occur in low frequency

),( 21jj BB

kk CL /3 2 1

L LL post-narrow l i nk j

3 2 1

recei ver si de

i i 1 k 2 k

cross traffi c

21

),( 21jj BB

kij

kij

and

and

2

1

3 2 1

1j 2

j

Cross traffi c di stort i on

path

Filtering scheme

1. filter out the estimates in case of

as the noises. 2. Of the remaining estimates, the estimate of lowest value and relatively

high frequency of occurrence is selected as the set of NLE. The mean of the NLE estimates is considered as the bottleneck of measured path.

),( 21jj BB

j

),( 21jj BB

Experimental ResultsSimulation setup ns-2 Topology

P={50,20,10,30,25,40} Mps 1000 packet triplet experiments are done.

Mbps5.0

Cont’dPacket-Pair vs. Packet-Triplet L=100bytes cross traffic load=20%,

50%, 80%

Cont’d L=700bytes CL=20%, 80%

Cont’d L=1000 bytes CL=20%, 80%

Conclusion

The noise filtering and bottleneck detection are always efficient whenever the cross traffic is light or heavy when we choose the small probing packet size how to set is a remaining issue for our research on this topic

Thank You !!!!!!