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LibraryConsensus2022Design paperCorpus record

Bullshark: DAG BFT Protocols Made Practical

Bullshark. Alexander Spiegelman, Neil Giridharan, Alberto Sonnino and Lefteris Kokoris-Kogias.

DAG-Rider is built for asynchrony and pays for it on the common path. Bullshark keeps a DAG and a local commit rule, but adds a fast path for when the network is timely. The paper also writes down a simpler partially synchronous version.

Bullshark keeps DAG-Rider's local ordering and adds a fast path for when the network is timely. A partially synchronous version in the same paper is the one the authors treat as small enough to implement. Safety remains a one-third quorum argument. A benchmark in the paper is not a service level.
Evidence
Primary paper
Re-measured
No
Assumptions
4
Records linked
3

Code

Source, repository, and what is actually hosted

  • arXiv:2201.05677https://arxiv.org/abs/2201.05677
  • The source URL is not a GitHub repository. No code remote is invented.
  • Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
  • Add to a reading list

01 Claim ledger

What the paper is allowed to say

Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.

  1. Claim 01 · Paper model

    The common case was the complaint

    DAG-Rider waits out asynchrony. Bullshark commits faster when messages arrive on time, and keeps an asynchronous fallback in the full protocol.

  2. Claim 02 · Paper model

    Two protocols, one paper

    The asynchronous Bullshark and the partially synchronous Bullshark are both specified. Citing the name without saying which one is incomplete.

  3. Claim 03 · Paper model

    Still a DAG

    The fast path does not go back to a single leader broadcasting a classical block. Vertices, rounds and quorum references stay.

  4. Claim 04 · Paper model

    The number is an experiment

    The paper describes a deployment of about fifty parties and a throughput it measured. That is evidence about that implementation, on that day, in that setup.

02 Three cuts

Observation, model, falsifier

A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.

  1. 01 The common case was the complaint

    Observation

    What the study says

    DAG-Rider waits out asynchrony. Bullshark commits faster when messages arrive on time, and keeps an asynchronous fallback in the full protocol.

    Model

    What has to hold

    A known committee and the usual one-third bound.

    Falsifier

    What would retire it

    Asynchronous Bullshark or the partially synchronous version?

  2. 02 Two protocols, one paper

    Observation

    What the study says

    The asynchronous Bullshark and the partially synchronous Bullshark are both specified. Citing the name without saying which one is incomplete.

    Model

    What has to hold

    Garbage collection must match the commit rule. Deleting a vertex the rule might need is a safety bug the paper is warning you not to invent.

    Falsifier

    What would retire it

    Asynchronous Bullshark or the partially synchronous version?

  3. 03 Still a DAG

    Observation

    What the study says

    The fast path does not go back to a single leader broadcasting a classical block. Vertices, rounds and quorum references stay.

    Model

    What has to hold

    The benchmark's hardware, batching and transaction size are not yours unless you reproduced them.

    Falsifier

    What would retire it

    How many rounds does the fast path need?

  4. 04 The number is an experiment

    Observation

    What the study says

    The paper describes a deployment of about fifty parties and a throughput it measured. That is evidence about that implementation, on that day, in that setup.

    Model

    What has to hold

    Garbage collection must match the commit rule. Deleting a vertex the rule might need is a safety bug the paper is warning you not to invent.

    Falsifier

    What would retire it

    Is a throughput figure tied to the paper's experiment or to a live chain?

03 Sequence

One action, as an operating tape

  1. 01Replicas build a round DAG by quoting a quorum of prior vertices.
  2. 02On the synchronous path, a commit rule fires after fewer rounds than the asynchronous fallback.
  3. 03The committed vertex drags its causal history into the total order.
  4. 04Garbage collection drops history the commit rule can no longer need.
  5. 05If the network stops being timely, the asynchronous rule is what the full protocol relies on for liveness.

04 Load-bearing

The argument, and where a pitch drops it

  1. Practical means specified

    The cut

    The authors' claim is that the partially synchronous protocol is short relative to its predecessors. Short is not the same as production-ready. Clients, mempools and membership are still outside the PDF.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    The committee is known. Later chains that cite Bullshark still have to say how validators are chosen.

  2. Fairness was traded

    The cut

    The paper is explicit that fairness under asynchrony is not DAG-Rider's fairness. A summary that keeps the fast path and the fairness sentence has misread it.

    Why it carries weight

    If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.

    Where it is dropped

    Fairness during asynchrony is weaker than DAG-Rider's. The paper says so.

05 Register

What has to be true

  • Model · Not re-measured

    A known committee and the usual one-third bound.

  • Network · Not re-measured

    For the fast path, periods when the network delivers on time.

  • Model · Not re-measured

    The benchmark's hardware, batching and transaction size are not yours unless you reproduced them.

  • Model · Not re-measured

    Garbage collection must match the commit rule. Deleting a vertex the rule might need is a safety bug the paper is warning you not to invent.

06 Divergence

What happened after the paper

Bullshark is the citation when a system says its DAG consensus is practical. Ask which of the two protocols it implemented, and do not let a 2022 experiment become a current capacity claim.

A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.

07 Pre-mortem

What to check before you use the idea

  5. 0 of 4 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.

08 Anatomy

The paper, in the order a builder needs

The problem it names

An asynchronous protocol that is optimal in the worst case can still be slow on an ordinary day. The paper wants the worst-case properties without making the common case wait for them.

What the design proposes

  • Vertices still form a round DAG by quoting a quorum of the previous round.
  • Under synchrony, a commit can happen on a shorter path than the asynchronous fallback.
  • The partially synchronous variant drops the asynchronous machinery and is offered as the implementation-sized protocol.

How the mechanism is specified

  • Safety stays with the quorum intersection. The fast path does not shrink the one-third bound.
  • The paper reports an implementation figure for a 50-party deployment. That figure is an experiment in the paper, not a live network's capacity.
  • Garbage collection is part of making the DAG practical. An unbounded DAG is not a product.

What this page does not treat as proven

  • A reported transactions-per-second number in a paper is not a service level.
  • The committee is known. Later chains that cite Bullshark still have to say how validators are chosen.
  • Fairness during asynchrony is weaker than DAG-Rider's. The paper says so.

Why the desk still reads it

Separate the experiment from the rule. The rule is a DAG plus a commit path. The experiment is one deployment. A venture that quotes only the number has not named the rule.

09 Lexicon

Terms, opened into the record

Fast path
The shorter commit rule Bullshark uses when the network is behaving synchronously.
Causal history
The vertices a committed vertex can reach, which become part of the ordered output.

10 Repository

Every linked record on this page

Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.

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.