Probe or Wait : Handling tail losses using Multipath TCP Kiran - - PowerPoint PPT Presentation

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Probe or Wait : Handling tail losses using Multipath TCP Kiran - - PowerPoint PPT Presentation

Oct 15, 2023 374 likes •570 views

Probe or Wait : Handling tail losses using Multipath TCP Kiran Yedugundla, Per Hurtig, Anna Brunstrom 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP Outline Introduction Handling tail losses Tail loss probe

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Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Kiran Yedugundla, Per Hurtig, Anna Brunstrom

Probe or Wait : Handling tail losses using Multipath TCP

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2 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Outline

  • Introduction
  • Handling tail losses
  • Tail loss probe (TLP)
  • Emulation Setup
  • Analysis
  • Proposed TLP modification
  • Evaluation
  • Conclusions
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3 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Introduction

  • Losses are common cause of performance degradation
  • Response time with losses is 10 times more than lossless

transfer -> Hurts latency sensitive applications

  • End to End losses handled by transport layer (TCP, MPTCP, .)
  • Loss recovery affected by location of packet loss in a packet

train or burst,

  • Short flows are more affected than long ones.
  • How TCP and MPTCP handles packet losses?
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4 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Introduction -MPTCP

  • Applications interact through the regular socket API
  • MPTCP manages the underlying TCP connections (subflows)
  • MPTCP acts as a ”middleware” between the socket API and the subflows
  • MPTCP requires additional signaling between end hosts to set up a connection,

adding subflows, and transmitting data

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5 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling packet losses -TCP

  • Retransmission timeout

Server Client

1 2 3 4 5 6 7 8 9 10 ACK: 5 Timeout 6

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6 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling packet losses -TCP

  • Fast retransmit -Duplicate ACK
  • Further improvements
  • Limited Transmit
  • Based on congestion state of

the connection

  • SACK, FACK
  • Not relevant for short

flows

Server Client

1 2 3 4 5 6 7 8 9 10 ACK: 5 6 ACK: 5 ACK: 5

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7 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling tail losses -TCP

  • Tail loss probe
  • Convert RTOs into fast recovery
  • Transmit loss probe after approx.
  • 2. RTT in absence of ACKs.
  • Retransmit last packet (or new if

available) to trigger fast recovery.

  • Early Retransmit

Server Client

1 2 3 4 5 6 7 8 9 10 ACK: 5 Loss probe: 10 2 RTT ACK: 5, SACK: 10 fast retrans:6 ACK: 10 FACK-based fast recovery CWND : 10 CWND : 7

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8 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling tail losses -MPTCP

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9 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling tail losses -MPTCP

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10 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling tail losses -MPTCP

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11 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Emulation Setup

Parameters WLAN/4G Link Capacity (Mbps) 54 Propagation Delay (ms) 20 ms – 120 ms Loss Deterministic Burst size 80 packets Seperation time 2s

Scenarios

Symmetric 20ms-20ms Asymmetric 20ms-30ms 30ms-20ms 20ms-120ms 120ms-20ms

Topology

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12 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Performance analysis -TCP

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13 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Performance analysis -MPTCP

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14 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Proposed TLP in MPTCP

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15 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Performance Analysis

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16 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Conclusions

  • Study tail loss recovery
  • Comparative analysis of handling tail losses with TCP

and MPTCP

  • Proposed a less conservative approach to handling

tail losses in MPTCP

  • Efficient in cases of probe loss or path loss
  • Efficient in cases with large asymmetry and loss on

higher delay path

  • Improvements of up to 50% in some scenarios
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17 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

MPTCP in Future Internet Transport

  • MPTCP – Ongoing research
  • Improving protocol
  • Improving throughput
  • Improving End-to-End Latency (This paper)
  • Usecases
  • Datacenters
  • 4G/WLAN Offload
  • MPTCP Proxies
  • Deployments
  • Apple Siri
  • Korean Telecom
  • Netvision Korea LTE/WiFi Traffic Aggregation Solution (MPAS)
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18 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Thanks

Q&A

Research work supported by: SIDUS READY Project

(RESEARCH ENVIRONMENT FOR ADVANCING LOW LATENCY INTERNET)

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19 Probe or Wait : Handling tail losses using Multipath TCP 12/06/2017

Handling packet losses -TCP

  • Fast retransmit - Selective ACK
  • Do not resend already

SACKed packets

  • Further improvements

with FACK congestion control

Server Client

1 2 3 4 5 6 7 8 9 10 ACK: 5, SACK 9 6 ACK: 5, SACK 9-10