Presentation on theme: "Nanyang Technological University Zou ZiXuan"— Presentation transcript:
1Nanyang Technological University Zou ZiXuan Packet Triplet: An Enhanced Packet Pair Probing for Path Capacity EstimationGood morning, welcome to my presentation—in which I will introduce an enhanced packet pair probing technique, called Packet Triplet for path capacity estimation.Nanyang Technological University Zou ZiXuan
2OUTLINE The purpose of Packet Triplet Previous Packet-Pair based techniquesPacket Triplet probingDetailed approachFiltering schemeExperimental ResultsThis is the outline of my presentation. First, I will introduce the purpose of Packet Triplet, then give the background knowledge of Packet-Pair based technique. After this, we proposed the detail of Packet Triplet technique, including Packet Triplet probing, detailed approach, the filtering scheme of packet triplet and our experimental results.
3The purpose of Packet Triplet Measuring the path capacity (bottleneck)Packet-Pair basedRobust to cross trafficWe developed Packet Triplet which is based on Packet-Pair scheme for the purpose of path capacity measurement, or say, the bottleneck measurement. We try to make the Packet Triplet robust to cross traffic, which means, with the existence of cross traffic among the measured path, we can also estimate the path capacity accurately.
4Previous Packet-Pair based technique Packet-Pair dispersionOriginated by Keshav for congestion controlCross traffic effect—expression and extensionVariants of Packet-Pair to deal with the effects of cross traffic.The principle of Packet-Pair dispersion is firstly proposed by Keshav in his TCP congestion control scheme. As the figure shows, two packets of same length L are sent back-to-back by the source. When these two packets arrive at the bottleneck link, they will be queued together in the buffer. After these packets are sent by the bottleneck link, they will be spread out in a time dispersion—delta=L/C, which is the transmission delay of the second packet at this link.
5Previous Packet-Pair based technique Statistical methodSending many packet pairs, using statistical approachUnion and IntersectionKernel densityDo not always lead to correct estimationNot a global modal but the local modalObserved by Paxson, investigated by Dovrolis
6Previous Packet-Pair based technique Model based detectionBased on Multimodal distributionPacket-Train and Packet-Pair
7Packet-Triplet probing Deal with multimodal distributionAccurately estimate path capacity in different load trafficDifferent from model-based detection
8Detailed approachThree back-to-back probing packets and dispersion pair
9Detailed approach Packet Triplet probing Idea condition No cross trafficThe variation of Latency of probing packetsEquivalent estimates
10Detailed approach Cross traffic effect When Narrow link capacity estimates (NLE)
11Cont’d Post-narrow link estimates (PNLE) Equivalent noise (EN) Occur in low frequency
12Filtering scheme filter out the estimates in case of as the noises. Of the remaining estimates, the estimateof 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.
17ConclusionThe noise filtering and bottleneck detection are always efficient whenever the cross traffic is light or heavy when we choose the small probing packet sizehow to set is a remaining issue for our research on this topic