Impact of IDONTWANT in the Number of Duplicates

Abstract

This Ethereum Research study analyzes the impact of the IDONTWANT message primitive on reducing duplicate message propagation in Ethereum's Gossipsub network following its adoption during the Pectra upgrade (with ~95% network adoption by May 2025). The research found that while IDONTWANT does provide modest improvements for larger messages like beacon blocks and blobs—increasing messages with zero duplicates from 2% to 9% and reducing average duplicates from 3 to 2—its effectiveness is significantly limited because approximately 70% of observed duplicates still arrive after IDONTWANT messages are sent, indicating that messages are already in transit by the time the control notification reaches peers. The study identified additional inefficiencies, including duplicates resulting from IWANT requests (~29% of cases) where nodes request messages that have already begun downloading, and instances where some protocol implementations fail to respect IDONTWANT signals and continue transmitting messages anyway. The researchers recommend improvements such as limiting IWANT message frequency, delaying initial IWANT requests to avoid requesting messages that are already arriving, ensuring implementations cancel IWANT replies upon receiving IDONTWANT, and fixing cases where published messages queued for transmission aren't cancelled when IDONTWANT is received.