Schlesi Testnet Is Latest Step in Long Road Toward Eth 2.0

Ethereum clients are beginning to sync and validate a new Eth 2.0 testnet, Schlesi, ahead of the network's prospective launch in July.

AccessTimeIconMay 7, 2020 at 4:47 p.m. UTC
Updated Sep 14, 2021 at 8:38 a.m. UTC

Another Eth 2.0 testnet, Schlesi, is live in what amounts to one more step in the trek toward the Proof-of-Stake (PoS) Eth 2.0, the next iteration of the Ethereum blockchain.

Named after a rail line stop in Berlin, Schlesi is a multi-client testnet laying the foundation for Eth 2.0’s backbone, the beacon chain. As of April 27, two teams – the Lighthouse client from developer Sigma Prime and Prysm from Prysmatic Labs – have synced and are actively validating the network, according to a tweet from testnet coordinator Afri Schoedon. 

Nimbus, a mobile client version of Eth 2.0 for use in small hardware devices, and PegaSys’s Teku have also successfully synced with the network, according to a pair of recent tweets from the teams. Nimbus expects to officially join the testnet with the other clients in the coming days, according to a team blog post on May 1.

Schlesi is the first multi-client testnet for Eth 2.0’s beacon chain with the intention to show that “clients are ready to support a potential beacon-chain mainnet,” according to the Schlesi GitHub. The launch of the beacon chain is the first tangible application of Eth 2.0 under the title “Phase 0.”

Road to Eth 2.0

To overgeneralize, Lighthouse, Prysm and Nimbus are experimenting with the spinal cord of Eth 2.0, the beacon chain. Eight teams are currently working on Eth 2.0 clients with three teams currently participating in this testnet. 

Originally, Ethereum was built with the intention of a future switch from a Proof-of-Work (PoW) consensus algorithm to a PoS algorithm. These algorithms decide how transactions are processed over blockchains given that every movement is recorded by all the computers partaking in the network’s activities. PoS has been viewed as a possible alternative to PoW given the high costs of running a PoW blockchain for both environmental and financial reasons.

Moving a running network from one algorithm to the next is not a humble operation, however.

“The transition is risky, highly complex and will take a considerable amount of time,” a report published by BitMEX Research this week found.

From a developer’s perspective, the new chain will be created in two parts: groupings of ether (ETH) investors who deposit ETH into the network to act as transaction validators and the beacon chain, which coordinates the validators.

Those validators are further organized into 64 “shards,” akin to ribs connected to the Beacon chain spinal cord. These shards will settle accounts and balance on the new Ethereum network as coordinated by the beacon chain, the spine of Eth 2.0. 

Testing, testing, 1, 2, 3

The recent testnets themselves show the redundancies necessary to make this transition possible, Schoedon told CoinDesk. 

“There will not be ‘the multi-client testnet,’ rather there will be many testnets with different life expectations and different testing scopes,” Schoedon said.

Indeed, Schlesi was preceded by the Goerli testnet over a year ago and numerous individual testnets run by the various Schlesi clients.

As CoinDesk reported in January 2019, Prysmatic Labs experimented with moving ETH onto the community-run Goerli testnet by depositing tokens representing ETH into a smart contract to be redeemed on Eth 2.0.

Goerli testnet schematic.
Goerli testnet schematic.

Now that Schlesi is live, attention will eventually turn to private testnets for practicing validation across different clients followed by public multi-client testnets that ETH holders will be encouraged to stress-test by joining, Schoedon said. 

Stretches before sprints

“Like all our testnets, this one was created to push the boundaries of technology and see how far we can go,” Nimbus research and development lead Jacek Seika said in an email to CoinDesk.

Seika said the Nimbus team had been running various testnets since March. Its Eth 2.0 lite client specification should be able to run on small devices such as a cellphone with the intention of democratizing access to participating in the network. The concept was a key reason Ethereum researchers gravitated toward staking as opposed to PoW mining.

“The goal is to lower the barrier of entry allowing a wider audience to participate,” Seika said.

Of course, the road ahead is still long. 

An official multi-client testnet run by the Ethereum Foundation is expected before the launch of Eth 2.0’s Phase 0, planned for as early as July, according to Eth 2.0 researcher Justin Drake (Dates still vary, however: Schoedon said the launch could be as late as 2021.)

Either way, it’s clear Eth 2.0 is making advancements. Sigma Prime co-founder Paul Hauner said the smaller testnets like Goerli or Schlesi would be considered successful if various clients could sync up together, as they did. For larger testnets, the bar will be higher.

“A coordinated, long-lived testnet I think will be successful once it’s been running for a couple of months, withstanding use from the public and co-ordinated attacks from security firms like Sigma Prime,” Hauner said.


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