1 / 10

LISA: A Linked Slow-Start Algorithm for MPTCP

This algorithm reduces loss and improves Flow Completion Time (FCT) in MPTCP by avoiding a multiple Initial Window (IW) burst mixed with ongoing Slow Start (SS). It has been tested in emulation and real-life testbeds and has been published at IEEE ICC 2016. Feedback and reviews are needed.

delilahj
Download Presentation

LISA: A Linked Slow-Start Algorithm for MPTCP

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. Update on LISA:A Linked Slow-Start Algorithm for MPTCPdraft-barik-mptcp-lisa-01 plan: ICCRG Runa Barik, Simone Ferlin, Michael WelzlUniversity of Oslo 97th IETF Meeting Seoul15 November 2016

  2. Context • This is a simple algorithm that avoids a multiple-IW burst mixed with ongoing SS • Reduces loss, improves Flow Completion Time (FCT) • In emulation and in real-life testbed (NorNet) • Published at ICCRuna Barik, Michael Welzl, Simone Ferlin, Ozgu Alay: "LISA: A Linked Slow-Start Algorithm for MPTCP", IEEE ICC 2016, Kuala Lumpur, 23-27 May 2016. • Presented to MPTCP at IETF 94 • Feedback: show results with different BDP • Presented to MPTCP at IETF 96 • Very little time, doesn’t fit charter

  3. Context /2 • Decision: discuss it in ICCRG • If MPTCP charter updated to allow congestion control changes, bring it back there • Else publish it via ICCRG as Experimental IRTF doc • Need reviews!

  4. What’s the problem? • No coupling in SS • Does not seem necessary: subflow 1 doubles, subflow 2 doubles  aggregate doubles • However, IW of new subflows starting makes this different • New subflows typically start at the same time, while SS is already ongoing • E.g. 8 subflows = SS + IW70 2 subflows, shared bottleneck: 2.5Mbps, 70mstransfer size: 300KB

  5. Short overview • LISA tries to be no more aggressive than one TCP during SS • Basic approach in LISA: • From subflows in SS, select subflow with maximum sending rate (max_subflow) • From max_subflow’s cwnd, take between 3 and 10 packets as “packet credit” to give new_subflow as IW • Max_subflow does not increase cwnd for (packets_inflight – cwnd) ACKs • If no max_subflow, IW of new_subflow = 10

  6. Previously shown results • Retransmissions & completion time, depending on: • File size: problem does not occur with very small files (need to send multiple IWs), and becomes less relevant for very large files • Queue length: whether queue exceeded heavily (many losses & retransmissions  long FCT) or not is a matter of luck: depends on how (# subflows*IW) aligns with(BDP+queue). By reducing the burst, LISA sometimes helps • Number of subflows: more subflows make the problems worse and the effect of LISA better • RTT, Bandwidth: varying BDP has similar effect to varying queue length

  7. Example result: non-shared BN This is a “lucky-BDP” case...

  8. Non-shared bottleneck5Mbps, 40ms, 2 subflows At the end of slow start (after loss recovery) Retransmissions until then

  9. Shared Bottleneck5Mbps, 40ms, 2 subflows At the end of slow start (after loss recovery) Retransmissions until then

  10. Next steps • LISA paper, draft, presentations, Linux kernel patch available from:http://heim.ifi.uio.no/~runabk/lisa/ • Please read & comment!

More Related