Ethereum Foundation Blog: The last testnet is about to be merged. What do we need to do?

After several years of hard work bringing Proof of Stake to Ethereum, we have now entered the final testing phase: testnet deployment!

As the last testnet to make the transition to proof-of-stake, Goerli will merge with Prater. The Goerli/Prater merged network will retain the Goerli name.

The Bellatrix upgrade to prepare for the Prater testnet merge will be activated at epoch 112260, estimated time is 12:24PM UTC on August 4, 2022

After the Bellatrix upgrade is activated, the Goerli/Prater merger will occur when Goerli reaches a total difficulty value of 10,790,000, which is expected to occur between August 6-12, 2022.

After the merger, Goerli’s validator set will remain open to individual stakers running testnet validators. Staking vehicles looking to start a Goerli/Prater validator can head to the Prater Launchpad.

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After several years of hard work bringing Proof of Stake to Ethereum, we have now entered the final testing phase: testnet deployment!

After several development testnets, shadow forks, and abandoned testnets, Sepolia recently transitioned to proof-of-stake. Now, there is only one testnet left: Goerli and its matching beacon chain, Prater.

The merge differs from previous Ethereum upgrades in two ways. First, node operators need to upgrade both their consensus layer (CL) and execution layer (EL) clients, instead of just one of the two. Then, the upgrade is activated in two phases: the first phase is the Bellatrix upgrade, which is activated at a public epoch height on the beacon chain, and the second is the Paris upgrade, which is activated when a Total Difficulty value is reached on the execution layer.

Upgrade information

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The merger is a two-step process. It starts with the Bellatrix network upgrade on the consensus layer, triggered by an epoch height. Next comes the Paris upgrade on the execution layer, which transitions from proof-of-work to proof-of-stake, triggered by a specific Total Difficulty threshold, called Terminal Total Difficulty (TTD).

The Bellatrix upgrade is scheduled to activate on epoch 112260 of the Prater beacon chain, expected at 12:24PM UTC on August 4, 2022. The Paris portion of the execution layer will be triggered when the Terminal Total Difficulty (TTD) on the Goerli testnet reaches 10790000, expected between August 6-12, 2022.

Once the execution layer exceeds the TTD, the next block will be produced entirely by beacon chain validators. Once the beacon chain finalizes the block, we consider the merge to be complete. Assuming normal network conditions, this should be completed 2 epochs after the first block after the TTD, which is about 13 minutes!

There is a new JSON-RPC block tag finalized, which returns the latest finalized block, or an error if no such merged block exists. This tag can be used by applications to check if a merge has completed. Similarly, smart contracts can query the DIFFICULTY opcode (0x44), which has been renamed PREVRANDAO after the merge, to determine if the merge has occurred. We recommend that infrastructure providers monitor the stability of the entire network in addition to the finalization status.

Client version

The following client versions support the merge of the Goerli and Prater testnets. Node operators must run an Execution Layer (EL) client and a Consensus Layer (CL) client to stay on the network during and after the merge.

When choosing which client to run, validators should be especially aware of the risks of running majority clients on EL and CL. These risks and their consequences can be explained in this article. An estimate of the current distribution of EL and CL clients and a guide to switching from one client to another can be found in this article.

Consensus Layer

• Lighthouse Geardude Clockberg (v2.4.0)

• Lodestar v0.41.0

• Prysm v2.1.4-rc.0

• Nimbus v22.7.0

• Teku 22.7.0

Execution Layer

• Besu 22.7.0-RC3

• Erigon 2022.07.03-alpha

• go-ethereum (geth) v1.10.21

• Nethermind 1.13.5

Upgrade Specifications

The consensus-critical changes that were merged are detailed in two places:

Changes to the consensus layer, in the bellatrix directory of the consensus specification repository

Changes to the execution layer, in the Paris spec of the execution specification repository

Additionally, two other specifications cover how consensus and execution layer clients interact:

The Engine API is described in the execution-apis repository and is used for communication between the consensus layer and the execution layer.

Optimistic Sync is described in the sync folder of the consensus specification repository. It is used by the consensus layer to import blocks when syncing with the execution layer, and to provide the execution layer with a partial view of the consensus layer chain head.

FAQ

What should I do as a node operator?

After the merger, an Ethereum full node will combine a consensus layer client (running the PoS beacon chain) and an execution layer client (managing user state and running transaction-related calculations). They communicate through an authenticated port (using a new set of JSON RPC methods, called the Engine API). The execution layer client and the consensus layer client use an encrypted JWT to verify each other. Node operators need to refer to their client documentation to learn how to generate and configure this information.

In other words, if you already run a node on the beacon chain, you now also need to run an execution layer client. Likewise, if you are running a node on the current PoW network, you will need to run a consensus layer client. In order for them to communicate securely, a JWT token must be passed to each client. A brief description of running a node on the Goerli/Prater network can be found here.

It is worth emphasizing that while both the beacon chain node and the validator client are part of the consensus layer client, running a beacon chain node is not the same as running a validator client. Validators must run both, while node operators only need to run the beacon chain node. This article explains the difference between the two components in more detail: https://docs.ethhub.io/ethereum-roadmap/ethereum-2.0/eth-2.0-client-architecture/

Also, please note that both the consensus and execution layers will maintain an independent set of peers and expose its own API. Both the Beacon and JSON RPC APIs will continue to work as expected.

What do I need to do as a staker?

The Goerli/Prater merge is the last chance for everyone to ensure their validators are configured correctly before the mainnet transition. We strongly recommend participating in this merge to avoid any unexpected issues on mainnet.

As mentioned above, after the merge, validators on the beacon chain will need to run an execution layer client in addition to their consensus layer client. We strongly recommend doing this before the merge, but validators can outsource these functions to a third-party provider. This is possible because the only data the execution layer needs is updates to the deposit contract.

After the merger, validators need to ensure that the transactions in the blocks they create and attest to are valid. In order to do this, each beacon node must be paired with an execution layer client. Note that multiple validators can still be paired with a beacon node and execution layer client combination. While this increases the responsibility of validators, it also entitles the validator who proposed the block to receive the priority fee for its associated transactions (currently this fee is captured by miners).

While validators’ rewards accumulate on the beacon chain and are not available until a subsequent network upgrade, transaction fees will continue to be paid, burned, and distributed at the execution layer. Validators can specify any Ethereum address as the recipient of transaction fees.

After updating your consensus layer client, make sure to set the fee recipient when setting up your validator client to ensure that transaction fees are sent to an address you control. If you choose a third-party provider to stake, it is up to the provider you choose to specify how these fees are distributed.

The Prater Staking Launchpad has a merge preparation checklist that validators can use to ensure they have completed each step of the process. The EthStaker team will also be hosting a merge validator preparation workshop on July 29th.

Why is the estimated time span for Terminal Total Difficulty so long?

The increased difficulty fluctuations with each block make estimates of TTD more difficult than block or epoch heights, so a wider range is expected. Users should note that this will also occur during the transition period of the mainnet due to changes in the proof-of-work hash rate.

As an app or tool developer, what should I do?

The Goerli testnet is preparing for the merge, and now is your last chance to ensure that your products have successfully made the PoS transition and are running as expected in the merged environment. As mentioned in the previous blog post, the merge will only have a very subtle impact on a subset of contracts deployed on Ethereum and should not break any contracts. In addition, most user application program interface (API) endpoints will remain stable (unless using proof-of-work specific methods such as eth_getWork).

Still, most applications on Ethereum involve much more than on-chain contracts. Now it's up to you to make sure your frontend code, tooling, deployment pipelines, and other off-chain components work as expected. We strongly encourage developers to perform a full test and deploy cycle on Ropsten (or Kiln) and report any issues with tools or dependencies to the maintainers of those projects. If you're not sure where to create an issue, use this repository.

In addition, you should note that all testnets except Sepolia and Goerli will be shut down after the merger. If you are a user of Ropsten, Rinkeby or Kiln testnets, you should plan to migrate to Goerli or Sepolia testnets. For more detailed information, please read the article "Ropsten, Rinkeby and Kiln Testnet Deprecation Announcement".

As an Ethereum user or ETH holder, what do I need to do?

No. The Ethereum mainnet is not affected by this testnet. We will make a follow-up announcement in this blog before the mainnet transition.

What do I need to do as a miner?

No. If you are mining on the Ethereum mainnet or Sepolia testnet, you should be aware that after the merger each network will run entirely under the PoS consensus. At that time, mining will no longer be possible on that network.

As a validator, can I withdraw my staked assets?

No. The merge is the most complex upgrade to Ethereum to date. To minimize the risk of network disruption, we took a minimum viable approach, which meant that we put aside all changes not related to the PoW->PoS transition for this upgrade.

The ability to withdraw funds from the beacon chain may be introduced in the first upgrade after the merger. The consensus layer and execution layer specifications are being promoted.

I have more questions, where can I ask?

The EthStaker community has set up a discord channel to answer questions from stakers and node operators. You can join their discord and ask for help in #goerli-prater. As mentioned above, EthStaker will also host a merged validator preparation workshop on July 29th.

Additionally, a merged community call is scheduled for August 12th at 14:00 UTC. Client developers and researchers will answer questions from node operators, stakers, infrastructure & tooling providers, and community members. Please note that this community call is expected to take place after the Goerli/Prater merge.

When will the merger take place?

As of this posting, there is no date for the Ethereum mainnet merge. Any talk of a merge date is likely a scam. Updates will be posted on the Ethereum Foundation blog, don’t be fooled!

Assuming the Goerli/Prater merge does not reveal any issues, when the client releases a feature-complete version, we will select the slot height to activate the Bellatrix upgrade on the mainnet beacon chain, as well as set the total difficulty value to trigger the mainnet transition. The client will release a version for the mainnet merge. We will announce the news on this blog and other community platforms.

This assumes that no issues are found. If at any point in the process issues are found, or testing coverage is judged to be incomplete, we will resolve those issues before moving forward with deployment.

Only then will it be possible to estimate the exact date of the merger.

That means soon.

Original link: https://blog.ethereum.org/2022/07/27/goerli-prater-merge-announcement/