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

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 (TLP) • Emulation Setup • Analysis • Proposed TLP modification • Evaluation • Conclusions • 2 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

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? • 3 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

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 4 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Handling packet losses -TCP Server Client Retransmission timeout • 1 2 3 4 5 6 7 8 9 10 Timeout ACK: 5 6 5 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Handling packet losses -TCP Server Client Fast retransmit -Duplicate ACK • 1 2 3 Further improvements • 4 5 6 Limited Transmit 7 • 8 9 Based on congestion state of 10 • ACK: 5 the connection ACK: 5 ACK: 5 6 SACK, FACK • Not relevant for short • flows 6 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Handling tail losses -TCP Server Client CWND : 10 Tail loss probe • 1 2 3 Convert RTOs into fast recovery • 4 5 Transmit loss probe after approx. • 6 7 2. RTT in absence of ACKs. 8 9 Retransmit last packet (or new if • 10 available) to trigger fast recovery . ACK: 5 2 RTT Early Retransmit • Loss probe: 10 ACK: 5, SACK: 10 FACK-based fast retrans:6 fast recovery ACK: 10 CWND : 7 7 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

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

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

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

Emulation Setup Topology Parameters WLAN/4G Scenarios Link Capacity (Mbps) 54 Symmetric 20ms-20ms Propagation Delay (ms) 20 ms – 120 ms Asymmetric 20ms-30ms 30ms-20ms Loss Deterministic 20ms-120ms 120ms-20ms Burst size 80 packets Seperation time 2s 11 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

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

Performance analysis -MPTCP 13 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Proposed TLP in MPTCP 14 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

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

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

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) • 17 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Research work supported by: SIDUS READY Project (RESEARCH ENVIRONMENT FOR ADVANCING LOW LATENCY INTERNET) Thanks Q&A 18 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP

Handling packet losses -TCP Server Client Fast retransmit - Selective ACK • 1 2 3 Do not resend already • 4 5 SACKed packets 6 7 8 Further improvements • 9 10 with FACK congestion ACK: 5, SACK 9 control ACK: 5, SACK 9-10 6 19 12/06/2017 Probe or Wait : Handling tail losses using Multipath TCP