1 / 24

End-to-end Asymmetric Link Capacity Estimation

End-to-end Asymmetric Link Capacity Estimation. Ling-Jyh Chen, Tony Sun, Guang Yang, M.Y. Sanadidi, Mario Gerla Dept. of Computer Science, University of California at Los Angeles. Definition. Capacity : maximum IP-layer throughput that a flow can get, without any cross traffic.

justis
Download Presentation

End-to-end Asymmetric Link Capacity Estimation

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. End-to-end Asymmetric Link Capacity Estimation Ling-Jyh Chen, Tony Sun, Guang Yang, M.Y. Sanadidi, Mario Gerla Dept. of Computer Science, University of California at Los Angeles

  2. Definition • Capacity: maximum IP-layer throughput that a flow can get, without any cross traffic. • Available Bandwidth: maximum IP-layer throughput that a flow can get, given (stationary) cross traffic.

  3. Previous Work on Capacity Estimation • Per-hop based • pathchar: use different packet sizes to probe the per-hop link capacity • clink, pchar: variants of pathchar • Nettimer: use “packet tailgating” technique • End-to-end based • Pathrate, Sprobe, CapProbe • These approaches are either one-way based or unable to estimate asymmetric link capacities.

  4. Estimating Asymmetric Links • Asymmetric links are becoming popular (e.g. DSL, cable modems, and satellite links). • Knowing the capacity of BOTH direction links is important for applications. • Related work: • ALBP [Yu et al, ICC’03] employs a multi-packet delay model to estimate “per-hop” capacity of asymmetric links.

  5. Our Contribution • We propose an end-to-end asymmetric link capacity estimation technique, called AsymProbe. • AsymProbe is CapProbe based: • round trip method • packet pair based • simple, fast, and accurate

  6. 20Mbps 10Mbps 5Mbps 10Mbps 20Mbps 8Mbps T1 Narrowest Link T2 T3 T3 T3 T3 Packet Pair Dispersion Capacity = (Packet Size) / (Dispersion)

  7. Issues: Compression and Expansion • Queueing delay on the first packet => compression • Queueing delay on the second packet => expansion

  8. Capacity CapProbe (Rohit et al, SIGCOMM’04) • Key insight: a packet pair that gets through with zero queueing delay yields the exact estimate. • CapProbe uses “Minimum Delay Sum” filter.

  9. Proposed Approach: AsymProbe

  10. AsymProbe: Example C=P/T

  11. AsymProbe Algorithm • AsymProbe has four phases: • Phase 1: the probing phase (P1=Pmax ; P2=Pmax ) (=> CapProbe) • Phase 2: the probing phase (P1=Pmax ; P2=Pmin) • Phase 3: the probing phase (P1=Pmin ; P2=Pmax ) • Phase 4: the decision phase

  12. AsymProbe Algorithm • The decision phase:

  13. Issues • AsymProbe is able to estimate asymmetric link capacities when the “asymmetric ratio” is larger than Pmin /Pmax and smaller than Pmax /Pmin. • AsymProbe can not estimate “extremely asymmetric” links. • Pmax is limited by MTU. • Pmin is limited by the supported system time resolution.

  14. Simulation • AsymProbe: A <-> B; Cross Traffic: C <->B • E->D: 1.5Mbps; D->E: 128kbps

  15. Simulation Results • Pmax=1500 bytes ; Pmin=100 bytes

  16. Emulation • Pmax=1500 bytes ; Pmin=500 bytes

  17. Emulation Results

  18. Internet Experiments • P1=1500 bytes, P2=500 bytes • Supported “asymmetric ratio” = 3:1

  19. Application – TCP Probe • The concept of AsymProbe can be integrated with other data transmission protocols, e.g. TCP. • TCP packet size: • forward direction: TCP data 1500 bytes • reverse direction: TCP ACK 40 bytes • According to AsymProbe algorithm: • If , then T1>T2TCP Probe estimates the capacity of the forward direction link • If , then T1<T2TCP Probe estimates the capacity of the reverse direction link

  20. CapProbe: DelAck TCP Probe: TCP Probe • More details in [Anders et al, GI’05]

  21. TCP Probe Application • Vertical handoff usually results in a dramatic change in the path capacity. • Service agility using “Fast Rate Adaptation” (FRA) algorithm • FRA forces TCP to enter Slow Start when detecting a handoff from LOW to HIGH

  22. Service Agility – TCP Probe • TCP Probe with “fast rate adaptation” • Vertical handoff from 10Mbps to 100Mbps Unit: bps

  23. Summary • We propose an end-to-end asymmetric link capacity estimation technique, called AsymProbe. • We evaluate AsymProbe by simulation and Internet experiments. • The concept of AsymProbe can be integrated with other data transmission protocols. • We present a passive capacity estimation technique, called TCP Probe, which integrates AsymProbe with TCP.

  24. Thanks! CapProbe: http://nrl.cs.ucla.edu/CapProbe/

More Related