Fitting Square Pegs Through Round Pipes: Unordered Delivery Wire-Compatible with TCP and TLS

TL;DR

Minion provides a backward-compatible architecture for unordered delivery over TCP and TLS, improving application performance without requiring major stack modifications.

Contribution

It introduces OS API extensions and protocols enabling true unordered datagram delivery atop TCP and TLS, compatible with existing stacks.

Findings

Improves performance of conferencing, VPN, and web browsing applications.

Minimal CPU and bandwidth overhead.

Works with unmodified TCP stacks, with benefits from partial upgrades.

Abstract

Internet applications increasingly employ TCP not as a stream abstraction, but as a substrate for application-level transports, a use that converts TCP's in-order semantics from a convenience blessing to a performance curse. As Internet evolution makes TCP's use as a substrate likely to grow, we offer Minion, an architecture for backward-compatible out-of-order delivery atop TCP and TLS. Small OS API extensions allow applications to manage TCP's send buffer and to receive TCP segments out-of-order. Atop these extensions, Minion builds application-level protocols offering true unordered datagram delivery, within streams preserving strict wire-compatibility with unsecured or TLS-secured TCP connections. Minion's protocols can run on unmodified TCP stacks, but benefit incrementally when either endpoint is upgraded, for a backward-compatible deployment path. Experiments suggest that Minion can noticeably improve performance of applications such as conferencing, virtual private networking, and web browsing, while incurring minimal CPU or bandwidth costs.