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Dumbo: Faster Asynchronous BFT Protocols

Dumbo. Bingyong Guo, Zhenliang Lu, Qiang Tang, Jing Xu and Zhenfeng Zhang.

Dumbo reduces the cost of the asynchronous path by improving the reliable broadcast and the binary agreement that HoneyBadger-style protocols stack together.

A reading of the public paper. Not a copy, not a benchmark, and not a claim about any later network.

A chain that claims asynchronous finality should say which broadcast and which agreement it uses. Dumbo is one answer.

The five-minute read

The defect

Asynchronous Byzantine agreement does not wait for a timeout, and the practical protocols were too expensive in rounds and messages.

The proposal

Dumbo reduces the cost of the asynchronous path by improving the reliable broadcast and the binary agreement that HoneyBadger-style protocols stack together.

Asynchrony means the protocol may not use a timeout for safety or livene

The improvement is in the reduction, not in a new trust assumption.

The bound

This is not a public proof-of-stake chain.

One action, walked through

  1. Broadcast a proposal with the cheaper reliable broadcast.
  2. Agree bit by bit, or by batch, with the binary agreement.
  3. Output when the asynchronous termination condition holds.
  4. What is the committee?

The argument, unpacked

What the paper is for

A chain that claims asynchronous finality should say which broadcast and which agreement it uses. Dumbo is one answer.

What happened after

Dumbo-NG and later DAG protocols keep pushing the same asynchronous cost. The 2020 paper is the reduction, not those systems.

What has to be true

  • This is not a public proof-of-stake chain.
  • Faster than HoneyBadger in the paper is not a TPS number for a product.
  • The committee is permissioned.

What happened after the paper

Dumbo-NG and later DAG protocols keep pushing the same asynchronous cost. The 2020 paper is the reduction, not those systems.

What to check before you use the idea

  • Does liveness depend on a timeout?
  • What is the committee?
  • Which broadcast is on the hot path?

Terms

Asynchronous BFT
Agreement without a timing assumption for termination.
Reliable broadcast
A primitive that delivers the same message to every honest replica.

The problem the paper names

Asynchronous Byzantine agreement does not wait for a timeout, and the practical protocols were too expensive in rounds and messages.

What the design proposes

  • Asynchrony means the protocol may not use a timeout for safety or liveness.
  • The improvement is in the reduction, not in a new trust assumption.
  • A known committee is still assumed.

How the mechanism is specified

  • Broadcast a proposal with the cheaper reliable broadcast.
  • Agree bit by bit, or by batch, with the binary agreement.
  • Output when the asynchronous termination condition holds.

What this page does not treat as proven

  • This is not a public proof-of-stake chain.
  • Faster than HoneyBadger in the paper is not a TPS number for a product.
  • The committee is permissioned.

Why a venture studio still reads it

A chain that claims asynchronous finality should say which broadcast and which agreement it uses. Dumbo is one answer.

This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.

Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.