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Multipath Congestion Control. Wenpeng Zhou Instructor Andrei Gurtov. Contents . Introduction Related works Multipath TCP congestion control (MPTCP) Vertical handover Conclusions. Introduction . Host A. Increase end-to-end throughput Better load balancing Improve security
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Multipath Congestion Control Wenpeng Zhou Instructor Andrei Gurtov
Contents • Introduction • Related works • Multipath TCP congestion control (MPTCP) • Vertical handover • Conclusions
Introduction Host A • Increase end-to-end throughput • Better load balancing • Improve security • Cause packet reordering Host B
Related work • Split a single connection into multipath, for example, MPLS • There are multipath. Only primary path is considered • Multipath can be used simultaneously. • Packet reordering is a big problem.
Multipath TCP (MPTCP) Protocol (1/5) • Transmission timer • Acknowledgement • Congestion window assignment • Architecture
Transmission timer (2/5) • Reordering can trigger unnecessary retransmit/fast recovery. • DUPACK is not qualified in multipath. • We use transmission timer to reduce fast retransmit.
Acknowledgement (3/5) • Cumulative acknowledgement degrades TCP performance. • Selective acknowledgement such as SACK
Congestion window assignment (4/5) • Different routes have different RTT • We focus on Relative Forward Delay (RFD)
Architecture (5/5) Every active receiving interface sends SACK Function block Sending side
Vertical handover Two solutions • Overbuffering • Explicit handover notification When handover happens, update RTT and RFD and retransmit the lost packets.
Conclusions • MPTCP reduces reordering to some extend • We can use MPTCP to vertical handover • Finding a bottleneck is not an easy task • Can we integrate MPTCP with HIP?