A Case for CATS: A Conductor-driven Asymmetric Transport Scheme for Semantic Prioritization

TL;DR

CATS introduces a conductor-driven transport scheme that enhances TCP's ability to prioritize critical data, significantly improving latency-sensitive application performance.

Contribution

This paper presents CATS, a novel framework that adds semantic awareness to TCP through a central Conductor, addressing limitations of traditional transport protocols.

Findings

Reduced First Contentful Paint by over 78% in tests

Demonstrated improvements without increasing total page load time

Addresses limitations of HTTP/1.1, HTTP/2, and HTTP/3 prioritization

Abstract

Standard transport protocols like TCP operate as a blind, FIFO conveyor belt for data, a model that is increasingly suboptimal for latency-sensitive and interactive applications. This paper challenges this model by introducing CATS (Conductor-driven Asymmetric Transport Scheme), a framework that provides TCP with the semantic awareness necessary to prioritize critical content. By centralizing scheduling intelligence in a transport-native "Conductor", CATS significantly improves user-perceived performance by delivering essential data first. This architecture directly confronts a cascade of historical performance workarounds and their limitations, including the high overhead of parallel connections in HTTP/1.1, the transport-layer Head-of-Line blocking in HTTP/2, and the observed implementation heterogeneity of prioritization in HTTP/3 over QUIC. Built upon TCP BBR, our ns-3 implementation demonstrates this principle by reducing the First Contentful Paint by over 78% in a representative webpage download configured as a deliberate worst-case scenario, with no penalty to total page load time compared to the baseline.