From the current results, after the gas fee on the Ethereum L1 mainnet has dropped to a 5-year low, many projects feel that deploying on L1 may not be impossible. Therefore, many people will ask, what core issues are L2 currently solving?

There is an old topic called the Blockchain Trilemma, which, according to Vitalik's explanation, means that one can only choose two out of three: [Security], [Decentralization], and [Scalability].

Returning to the essence of technology, this is the problem that L2 should solve:

First, state summaries are placed on L1, with the mainnet maintaining [Security];

Second, efforts are made on the sequencer to maintain [Decentralization] as much as possible;

Finally, [Scalability] is implemented as cleverly as possible off-chain by L2.

Different L2 solutions have their own merits, and everyone is familiar with OP Rollups and ZK Rollups. Today, I want to talk about something different, like Based-Rollup.

The Based L2 solution was also proposed by Vitalik early on, and L2 projects like Taiko have been promoting the Based Rollup idea.

PS: Note that it is Based, which has nothing to do with Coinbase's Base, which is also OP-based.

As we all know, in a standard OP-based L2 system, the sequencer holds significant power; it can decide whose transactions come first and whose come last, and even if it doesn’t act maliciously, it can profit through MEV. This is why projects like Metis propose decentralized sequencers.

Different L2s handle MEV differently: for example, Arb advocates for fair treatment of MEV (strictly first-come, first-served), while OP is more encouraging, considering MEV a free market behavior, thus taxing it. However, regardless of the approach, L2 sequencers have a prominent status.

Therefore, Based-Rollup chooses to take a stand against the sequencer—it aims to let ETH L1 do the sequencing, thus limiting the power of L2 sequencers.

Quoting a diagram from @taikoxyz’s documentation:

You can see that it follows a three-step process:

First, L2 searchers package L2 transactions and send them to L2 block Builders;

Second, L2 block Builders construct the blocks;

Third, L1 searchers include L2 blocks in the blocks they build on L1.

Here, the L1 searchers and L2 builders can be the same person.

This is a clever idea of 'doing two jobs'; in fact, the device performance of L1 searchers has redundancy, so constructing an additional L2 block for Taiko poses no pressure at all.

To make an inappropriate analogy, if we compare ETH and L2 to the relationship between a province and a city, the idea behind Based Rollup is: let the mayor (L2 builder) also serve as the deputy provincial governor (L1 searcher), thus utilizing L1's resources to safeguard L2's security.

It has been exactly a year since Taiko's TGE, and Token Unlock is about to start, so Taiko has also been brewing a new idea over the past year, called Based Booster Rollup/BBR.

Booster Rollup can also serve as a mirror for L1, and that idea is quite interesting. However, due to limited space, the analysis of Booster Rollup will be expanded in the next article.