Author: Todd Source: X, @0x_Todd
From the current results, after the gas fee of Ethereum L1 mainnet dropped to the lowest level in 5 years, many projects feel that it is not impossible to deploy on L1, so many people will ask, what core problems are L2 solving now?

There is an old topic called the impossible triangle of blockchain. According to Vitalik's explanation, you can only choose two among [security], [decentralization] and [scalability].
Back to the essence of technology, this is the problem that L2 should solve:
First, the state summary is placed on L1 and maintained by the main network [security];
Second, work hard on the sorter to keep [decentralization] as much as possible;
Finally, [scalability] is implemented as cleverly as possible by L2 off-chain.

Different L2 solutions have their own advantages. Everyone is familiar with OP Rollup and ZK Rollup. Today I want to talk about something different, such as Based-Rollup.
Based L2 solution was also first proposed by V God, and L2 such as Taiko has been pushing 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 sorter has great power. It can decide whose transaction comes first and whose transaction comes later, and even if it does not do evil, it can profit from MEV. This is why, for example, Metis proposed to build a decentralized sorter.
Different L2s have different solutions for MEV: for example, Arb advocates fair treatment of MEV (strictly first come, first served), while OP is more encouraging, believing that MEV is a free market behavior, so it imposes taxes on MEV. But no matter what, L2 sorters have a prominent position.
So Based-Rollup chose to wield the knife towards the sorter - its idea is to let ETH L1 do the sorting directly, so as to limit the power of the L2 sorter.
Quote a picture in the document by @taikoxyz:

You can see that it is a three-step process:
In the first step, L2 searchers package L2 transactions and send them to L2 block Builder;
In the second step, L2 block Builder builds blocks;
In the third step, L1 searchers include L2 blocks in the blocks they built on L1.
The L1 searcher and L2 builder here can be the same person.
This is another clever idea of "doing two jobs". In fact, the performance of the L1 searcher's equipment is redundant, and there is no pressure to do an extra Taiko L2 block construction.
To make an inappropriate analogy, if ETH and L2 are compared to the relationship between a province and a city, then the idea of Based Rollup is: let the mayor (L2 builder) serve as the deputy governor (L1 searcher), so that the resources of L1 are actually used to protect the security of L2.
It has been exactly one year since Taiko TGE, and Token Unlock will start soon, so Taiko has also brewed a new idea in the past year, called Based Booster Rollup/BBR.

Booster Rollup can also be used as a mirror of L1. That idea is also very interesting. However, due to limited space, the analysis of Booster Rollup will be expanded in the next article.