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Multiscale Traffic Processing Techniques for Network Inference and Control. R. Baraniuk R. Nowak E. Knightly R. Riedi V. Ribeiro S. Sarvotham A. Keshavarz R. King. NMS PI meeting Monterey November 2004. SPiN S ignal P rocessing i n N etworking. Effort 1.
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Multiscale Traffic Processing Techniques for Network Inference and Control R. Baraniuk R. Nowak E. Knightly R. Riedi V. Ribeiro S. SarvothamA. Keshavarz R. King NMS PI meeting Monterey November 2004 SPiNSignal Processing in Networking
Effort 1 Spatio-Temporal Available Bandwidth Estimation On-line localization of the tight link in a path
Key Definitions • Available bandwidth: left-over capacity on link • Tight link: link with least available bandwidth • Goal: • locate tight link in space and over time • using end-to-end probing
Applications • Science: where do Internet tight links occur and why? • Network aware applications • Server selection • Route selection • Network monitoring • - locating hot spots
Methodology Path available bandwidth Methodology: • For m>tight link, A[1,m] remains constant Sub-path available bandwidth
Packet Tailgating • Packet train contains: • Large packets stressing, with m hops life time • Small packets tailgating, full life time • Purpose: • Large packets “measure” bandwidth via their delay • Small packets transport this timing information to the receiver
Methodology Departure pattern Queuing against departure Real world experiments Number of chirps Estimation against true x-traffic Internet experiment 12 chirps Lite-probing: pathChirp • real world tool • Queuing delay cross traffic • Averaged excursions available resources • Light weight • Probe at various rates simultaneously • …converges in a handful of RTTs
avail time space Bandwidth: a Probabilistic entity • Available bandwidth depends on temporary congestion level of potential tight links UIUC – Rice Probability of being tight link Estimates taken 10 mins apart REAL WORLD EXPERIMENTS UIUC (J. Hou)– Rice Available sub-path bandwidth
STAB: Spatio Temporal available Bandwidth • STAB detects new tight link and reduced available bandwidth around 250 secs into simulation Estimate ns2 Simulation setting: Double web farm in ns2 (420 clients, 40 servers) Truth
GUI: ease of configuration • Running on windows • Instrumental for distribution and transfer
GUI in action • See Demo
Connection-level Analysis and Modeling of Network Trafficunderstanding the cause of burstsdetect changes of network state Effort 2
99% Mean Bursts and Dominance Connection level separation: • Detrimental bursts caused by the ONEstrongest connection • ….called Alpha connections Origin of Alpha: • High rate today from small RTT (round trip time) • Not congestion controlled Beta connections: • All the rest • Well controlled = + Overall traffic 1 Strongest connection Alpha Residual traffic Beta
Burst Model • Alpha traffic = High rate ON-OFF source • bottleneck at the receiver (TCP advertised window) Rate determined by RTT • Current state of measured traffic • Analysis: Queues will explode with TCP’s ability to achieve large rates (HSTCP, BIC) Beta (top) + Alpha Variable Service Rate • Queue-tail Weibull (as for self-similar • traffic) unless • rate of alpha traffic larger than • available bandwidth • and duration of alpha ON period heavy tailed
Free parameters Total Alpha Beta • Beta users: rate determines file size • Alpha users are “free” Duration - Rate Duration - Size X Size - Rate
SIMULATION Scheme RD: Rate Duration independent Scheme SD: Size Duration independent Scheme SR: Size Rate independent Real Trace Total Alpha Beta
Network-User Driven Traffic modelMixture fit of alpha-beta • Alpha: free to choose files RATE DISTRIBUTIONS • Beta: patience factor FILE SIZE DISTRIBUTIONS • RAPID PERFORMANCE ASSESSMENT • TCP Control: manages only BETA traffic effectively Congestion and admission control Alpha (SR) + Beta (RD) Original trace (Bellcore)
Effort 3 Model based Protocols
Prediction and what if scenarios • High-performance protocols pushed • HSTCP • STCP • XCP • FAST-TCP • BI-TCP • RTT bias • alpha-beta differentiation between flows more pronounced for STCP and HSTCP (which have large RTT bias). • Need for RTT-fair high-performance TCP
TCP Africa Adaptive and Fair Rapid Increase Congestion Avoidance • Hybrid two modes • Fast mode: (absence of congestion) • Rapid, opportunistic increase of window (rate) • Slow mode: (presence of congestion) • Linear (slow) increase in congestion avoidance • Congestion inference: • Current average RTT – minimal RTT (Vegas-type)
TCP Africa • Hybrid two modes • Fast mode: (absence of congestion) • Rapid, opportunistic increase of window (rate) • Slow mode: (presence of congestion) • Linear (slow) increase in congestion avoidance • Congestion inference: • Current average RTT – minimal RTT (Vegas-type) • Induces LOSSES infrequently (like Reno) • Combines aggressiveness of HSTCP with reliability and low loss induction of Reno
RTT Fairness • Against peers with different RTT • HSTCP: low RTT overwhelms • Africa: RTT bias is comparable to Reno
Safety • Degrade performance of other flows • …as compared to normal conditions • ns2 sim: Reno over 100Mbps link • …and with 1 Gbps Africa acceptable HSTCP poor Africa acceptable HSTCP poor
Software • STAB • pathChirp • Alpha-Beta decomposition • User Interface on Windows (GUI) • 80% completed • Free, available at spin.rice.edu
Publications Enable transition to DoD contractors • Note and understand • Write own code • IEEE Internet Computing Magazine • pathChirp and STAB • Computer Networks • Special issue on LRD traffic • Alpha-Beta / Network-User driven traffic model • IEEE Signal Processing • special issue on SPiN • IEEE SP Magazine • Special issue on Complexity in Networking • Network modeling, MWM, role of multifractal scaling • InfoCom 2005 • TCP Africa
Tech Transfer and Integration • GUI: Pathchirp Running on Windows • Raytheon: Doug Fowler discussing transitions pathChirp • Sensor networks: Steve Beck (BAE Austin) • Hitachi • David Diep makes pathChirp IPv4 and IPv6 compatible • Computer Sciences Corporation (DoD contractor) • Steve Tsang uses MWM for DSN VoIP User Interface • GridLab Project (Verstoep) • Deployed pathChirp for Grid computing measurements • SPAWAR (consulted Phuong Nguyen) • J9 (consulted Jasom Boyer) • GaTech (Riley-Fujimoto) • On-line pathChirp inference in integrated demo to detect UDP storms • UC Riverside (Faloutsos) • On-line Traffic estimation / demystify LRD • UIUC (Hou) and ISI (Heidemann) • Integration of probing schemes into network • simulators JavaSim and ns-2 • SLAC (Cottrell) • Large scale monitoring using pathChirp
Ongoing work • pathChirp: chirp-web • Tight links on high speed networks • Anomaly detection through chirp-web • a/b: Network/user-driven traffic model • Through simulation and measurements assess impact of protocols, applications, clientele, end-host server • Parameters from network and user specifications • High-speed protocols and congestion control • continue to integrate advanced modeling/probing techniques into new protocols