The initial TCP slow start phase seeks to ramp up data transmission rates quickly to meet available capacity but also to exit the slow start phase before causing undue congestion. Unfortunately, the typical default TCP implementation often exits slow start too early, before capacity has been reached, causing underutilization, particularly detrimental to networks with large capacities and high delays. This study introduces a novel enhancement to TCP slow start - Slow start Exit At Right CHokepoint (SEARCH) - where the link capacity is inferred at the server based on bytes delivered compared to the expected bytes delivered, smoothed to account for link latency variation and normalized to accommodate link capacities. Empirical evaluation over geosynchronous satellite links, low-orbit satellite links, and 4G LTE links shows our approach is a substantial improvement over default TCP implementations by not exiting slow start too early, but better than traditional TCP, too, by exiting slow start before encountering packet loss.

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See also:

• Maryam Ataei Kachooei, Jae Chung, Feng Li, Benjamin Peters, and Mark Claypool. SEARCH: Robust TCP Slow Start Performance over Satellite Networks, In Proceedings of the 48th IEEE Conference on Local Computer Networks (LCN), Daytona Beach, FL, USA, October 1-5, 2023. Online at: https://web.cs.wpi.edu/~claypool/papers/search-lcn-23/

• Maryam Ataei Kachooei, Pinhan Zhao, Feng Li, Jae Won Chung, and Mark Claypool. Fixing TCP Slow Start for Slow Fat Links, In Proceedings of the 0x16 NetDev Conference, Lisbon, Portugal, October 2022. Online at: http://www.cs.wpi.edu/~claypool/papers/tcp-best-netdev-22/

• Benjamin Peters, Pinhan Zhao, Jae Won Chung, and Mark Claypool. TCP HyStart Performance over a Satellite Network, In Proceedings of the 0x15 NetDev Conference, Virtual Conference, July 2021. Online at: http://www.cs.wpi.edu/~claypool/papers/tcp-hystart-netdev-21/