Rollips-based parsing: a sorting mechanism that does not require centralized operators

Rollup's promise and order-based regression

Rollup technology has promised to scale while maintaining Ethereum's security. But then, an embarrassing question surfaced: Most Rollups still rely on a single sorter to determine whose next transaction will be processed. Rollup based on sorting is a response to this.

In layman terms, the idea is: no longer trust servers run by Layer2 to sort your transactions, but let Ethereum's own block proposer perform this operation. The basic layer determines the order, and Rollup derives its own chain based on this order, with no centralized sorter in between.

This sounds concise. But in practice, it redistributes power, delay and maximum extractable value in new ways. Let's explore in depth how it works, its advantages, its flaws, and what we learned from Taiko's bumpy but enlightening summer.

A quick overview of core points

Who is responsible for sorting: Ethereum Layer1 proposer sorts Layer2 batches;Rollup follows this order to build its Layer2 blocks.
Main advantages: Eliminating a single Layer2 sorter as a bottleneck for censorship or activity; inheriting Ethereum's set of proposers.
Transfer of maximum extractable value: Value extraction activities shift to Layer1 builders/proposers and relays under the Pbs mechanism;Layer2 pre-confirmation becomes a market.
Trade-offs in user experience: 12-second slot rhythm, reliance on pre-confirmation, and occasional risk of reorganization; delays are tied to Layer1 conditions.
The continued importance of security: Proving that systems, data availability and cross-chain bridges remain critical. Ordering based designs cannot fix fragile certificates or vulnerable cross-chain bridges.
Real-world signals: Taiko's post-incident upgrade and cross-chain bridge restoration highlight how governance and proof interact with order-based design.

What does "order-based Rollup" mean?

At a macro level, a Layer2 needs to decide two things: the order of transactions and whether the resulting state is correct. Rollup, which is based on ordering, hands over the first task to Ethereum, while the second task is secured through cryptography and verification.

Minimize implementation recipe

Sort: Layer2 batches are submitted to Ethereum. Any batch order finalized on Layer1 is standard for Layer2.
Execution: Layer2 executes these sorted transactions according to its rules, and then publishes certificates (zero-knowledge certificates or fraud certificates) and data.
Derivation: Anyone can reconstruct the state of Layer2 from Layer1 data. This is the cornerstone of its neutrality.

It is not anything

It is not a guarantee of perfect fairness. Builders and proposers still choose which deals are included. The Pbs mechanism and relays affect this process.
It cannot replace proof. Decentralization of sorting does not verify state transitions. You still need strong proof.
It is not automatically faster. You need to endure Ethereum's slot rhythm and network congestion.

How Ethereum actually sorts your Layer2

Step-by-step process

You submit transactions to a Layer2 memory pool or gateway. Some projects also accept submission directly to Layer1 to ensure inclusion.
Builders preparing the next Ethereum block package Layer2 data (usually encoded in a blob of EIP-4844), which contains a batch of Layer2 transactions.
Current Layer1 proposers select winning blocks from competing builders under the Pbs mechanism. Any batch order in this Layer1 block becomes the normative order for Layer2.
The Layer2 node monitors Layer1, ingests batch data, and derives the next Layer2 block. They execute the transaction, update the status, and then continue.
In addition, Layer2 issued a certificate. In zero-knowledge proof Rollup, the prover generates a proof of validity for the batches that have been executed; in an optimistic setting, it relies on proof of fraud and the challenge window.

Most people will notice two details in practice: First, the 12-second slot. It sets the heartbeat that the Layer2 ordering will ultimately determine on Layer1. Second, build the market. If a small number of relays or builders dominate, they can become potential bottlenecks even if the sorters within Layer2 are not centralized.

Why remove the sorter, and what

clear advantages you can't get for free

Less unilateral power. There is no company-operated sorter to determine inclusion or covert extraction of value.
Consistency with Ethereum. If Layer1 is running normally, Layer2 can submit the sorted batches. Reduced custom failover paths.
A simpler decentralized narrative. The order is rooted in the same economic security as supporting Ethereum.

Issues to pay attention to

The user experience inherits the rhythm of Layer1. Inclusion and finalization feel like Ethereum, rather than a custom fast path that a centralized sorter can forge.
The maximum extractable value has not disappeared. It migrated. Builders and proposers have strong leverage, while relays can pool traffic.
Proof, data and cross-chain bridges still determine true security. Order-based Rollup cannot save you from weak provers or poorly designed cross-chain bridges.
Risk alert: Order-based Rollup reduces a central control point, but does not eliminate economic centralization in the Pbs relay or builder market. Please pay attention to these indicators.

Maximum Extractable Value, Pbs Mechanism, and Value Flow

Once Layer1 proposers rank your Layer2, any Layer2 arbitrage or sandwich trade suddenly enters the realm of Layer1 builder competition. In practice, this means:
Maximum extractable value across domains. Searchers can combine Layer1 and Layer2 opportunities within the same Layer1 block. This is good for efficiency, but focuses the advantages in the hands of the best-equipped builders.
Relay gravity. If most blocks are routed through a few Pbs repeaters, they become informal gatekeepers. This is not a single sorter, but similar.
Income sharing problem. Who captures the most extractable value of Layer2 now? Some design assumptions offer rebates to Layer2 or application layers; Layer1 is favored by default.

Professional tip: If you are building on a sort-based Rollup, where does pre-confirmation come from? Is it the Layer1 builder, a third-party service, or the soft confirmation promised by the Rollup team? Answers will affect your user commitments.

Reality of user experience: pre-confirmation, delay and reorganization

Most users don't care who sorts. They care how long it takes. Sorting-based Rollup allows you to experience the rhythm of the basic chain.
Delay: Expected inclusion time is bound to Layer1 slots. Under high loads, competition for blob space may intensify. Some Dapps add a pre-confirmation layer for a faster experience.
Pre-confirmations: These are soft commitments and are usually made by Layer1 builders who expect to win the slot. They are effective in most cases, but not absolute. If different blocks win or minor reorganization occurs, these commitments may expire.
Restructuring risk: Short restructurings are rare, but they do exist. They may sway pre-validation and change batch order. The wallet should show this nuance.

Professional tip: If your app requires a sub-second user experience, please show users a clear "soft" status before Layer1 is included, and a "final" status after a few slots. Don't confuse them.

Security, certification, cross-chain bridges, and the Taiko case

Sequence-based design does not eliminate the need for mature certification or invulnerable cross-chain bridges. Taiko, a zero-knowledge proof Rollup who embraces style-based design, taught the market a vivid lesson in the summer.

On July 2, 2026, Taiko completely reopened its cross-chain bridge after a June exploit. The incident initially resulted in the theft of approximately $1.7 million, and the TAIKO token soared 136% after the reopening news was announced. A rebound in prices does not equate to safety, but it shows how quickly market sentiment can shift once collateral is restored.

Taiko's own post-mortem analysis quantified the losses to the attackers as approximately US$1.748 million, which included approximately 295.972 ETH (approximately US$512,000), 675,761 USDC (approximately US$676,000), and 1,990,000 TAIKO (approximately US$172,000). Crucially, the team said that before it was reopened, the cross-chain bridge had been re-mortgaged at a 1:1 ratio.

At the same time, governance agencies have strengthened core agreements. The proposed Unzen upgrade, submitted to the DAO on July 7 and approved by the Security Council on July 14 (pending community veto), requires at least one zero-knowledge certificate for each block and is scheduled to be activated on the main network on August 6, 2026. This is a strong statement that sorting neutrality is not enough without reliable verification guarantees.

Market infrastructure has also taken note of this. After reviewing post-incident materials, South Korea's major exchanges Upbit and Bithumb removed TAIKO from trading warning or delisting watch lists on July 24;Upbit said it would resume deposits in three markets and warned of possible fluctuations during the recovery period. For the builders, the conclusion is simple: Cross-chain bridges are the explosion radius of reputation. Ring-based design cannot make up for this.

Practical perspective: If you are evaluating a order-based Rollup, read the cross-chain bridge documentation and prove the life cycle first. Then, look at the story of the sorter. In this order.

Taiko Lab infographic

This infographic shows how proof is checked and attack paths-visualizing the prover/authentication process and how a counterfeit SGX prover allows fraudulent Layer2 status to be accepted. This is important to understanding the risks in order-based designs.

Sort design comparison

Model: Centralized Layer2 sorter
Who determines the order: An operator operated by Rollup
Advantages: Quick confirmation, simple user experience, easy integration with builders
Main risks: censorship, downtime, opaque maximum extractable value capture
Notes: Usually promising to decentralize later

Model: Shared sorter network
Who determines the order: External committees or services
Advantages: Greater neutrality than a single operator, potential fairness rules
Main risks: New surface of trust, coordination complexity, reliance on another network
Note: Want to imagine a shared infrastructure like the emerging SSNs

Model: Order-based Rollup
Who determines the order: Ethereum proposer through Pbs
Advantages: Inheriting the decentralization of Layer1 proposer, reducing Layer2 capture risks
Main risks: Centralization of relays or builders, Layer1 delay, and transfer of maximum extractable value to Layer1
Notes: Pre-confirmation of becoming a market

Quick Due Diligence Checklist

For teams built on order-based Rollup

Certification: Is there mandatory certification for each block or cycle? What is the throughput and fault handling of the prover?
Data availability: Are batches released as blobs with clear retention and retrieval tools?
Pre-confirmation: Who releases them, how will they be priced, and what happens when there is a disagreement or reorganization?
Maximum Extractable Value Policy: Are there any revenue sharing plans or application-level protections, such as inclusion lists or auction rules?
Cross-chain bridge policy: mortgage, circuit breaker, incident response. Look for the quality and timeline of post-mortem analysis.
Monitoring: Track builder share, repeater concentration, reorganization statistics, and blob fee pressure.

Set expectations for users and integrators

: Soft validation and final validation should be clearly marked in the user interface and documentation.
Wallet prompt: Display Layer1 slot time and pre-confirmation status. Don't hide it.
retry logic: Be prepared for rare pre-confirmation failures. Line up for safe resubmission.
Cross-chain bridges: Priority is given to native cross-chain bridges with transparent accounting and timely auditing. Be wary of excessive generous ceilings or incentives.

Mistakes to Avoid

will equate order-based with complete decentralization. Pbs relays and builders remain important.
Promote the speed you can't cash in. If it didn't land on Layer1, it wouldn't be real.
Underestimating the maximum extractable value across domains. If your app is arbitrable, plan for it.

FAQs

Is sort-based Rollup faster than Rollup using a centralized sorter?
Usually not. A centralized sorter can issue instant soft acknowledgements. Sorting-based Rollup runs at the pace of Ethereum and relies on pre-confirmation for a quick experience.

Can censorship be blocked based on ranking?
It reduces the risk of censorship by a single operator because no Layer2 server controls sequencing. However, the centralization of builders and relays under Pbs may still affect inclusion. This is a diversion, not a panacea.

Where does the maximum extractable value flow in a order-based Rollup?
Most of it goes to Layer1 builders and proposers, who assemble blocks that carry Layer2 batches. Some protocols may add a mechanism to redirect value, but by default it flows to Layer1.

What will happen if Ethereum is reorganized?
Short reorganization may change the specification Layer2 batch order. Your Layer2 client will follow the new Layer1 chain. Pre-confirmations issued based on old views may fail.

Do I still need to trust cross-chain bridges?
Yes. The correctness of cross-chain bridges is separate from mortgage accounting and sequencing. The Taiko incident and its 1:1 re-mortgage before reopening emphasize that even for zero-knowledge proof Rollup based on sorting, cross-chain bridges can be the weakest link.

Does every block require zero-knowledge proof?
Strictly speaking, sorting is not necessary, but it enhances correctness. Taiko's Unzen step requires at least one zero-knowledge proof for each block, a clear move to transcend sequencing neutrality to enhance security.

Can applications get inclusion guarantees on sort-based Rollup?
Some designs are trying to include lists or builder commitments. In practice, the guarantee is probabilistic until the batch lands on Layer1. Please read your Rollup policy carefully.