# Blitz-starting QUIC Connections

## TL;DR

This paper proposes a method to eliminate Slow Start in QUIC by using bandwidth hints from clients, enabling faster connection setup and improved short flow fairness, with significant reductions in flow completion times.

## Contribution

It introduces a novel approach to bootstrap congestion windows in QUIC using client-provided bandwidth estimates, removing Slow Start and enhancing performance.

## Key findings

- Nearly 2x faster video load times for DSL clients
- Reduced flow completion times despite some packet losses
- Up to 12% increase in transfer volume due to losses

## Abstract

In this paper, we revisit the idea to remove Slow Start from congestion control. To do so, we build upon the newly gained freedom of transport protocol extendability offered by QUIC to hint bandwidth estimates from a typical web client to a server. Using this bandwidth estimate, we bootstrap congestion windows of new connections to quickly utilize available bandwidth. This custom flow initialization removes the common early exit of Slow Start and thus fuels short flow fairness with long-running connections. Our results indicate that we can drastically reduce flow completion time accepting some losses and thereby an inflated transmission volume. For example, for a typical DSL client, loading a 2 MB YouTube video chunk is accelerated by nearly 2x. In the worst case, we find an inflation of the transfer volume by 12% due to losses.