# Ethereum EL Discovery Update Traditionally, Ethereum Execution Layer used the **Discovery v4** protocol to find new peers. **Discovery v5** was also introduced in some clients, but it was not mandated. While the two protocols can be supported in parallel, we intend to **make v5 mandatory**, changing v4 to be optional, allowing clients to eventually **sunset v4 support**. For rationale, see [this document](https://github.com/ethereum/devp2p/blob/master/discv5/discv5-rationale.md). ## Tracker The following table tracks implementation status in EL clients, with proposed deadlines. | | EL Client | discv5 support | Discv5 current default | Discv4 current default | Discv4 off flag | Discv4 planned off | |-| -------- | -------- | -------- | -------- | -------- | -------- | | deadlines || by Jan 15, 2026 | **on** by Jan 31, 2026 | | | **off** by Glamsterdam | || **Geth** | supported ✓ | on [(v1.14.9+)](https://github.com/ethereum/go-ethereum/pull/30327) ✓ | on | \--discovery.v4=false || || **Nimbus** | supported ✓ | on ✓ | on ||| || **Besu** | [supported](https://github.com/hyperledger/besu/issues/4089) | off (\--Xv5-discovery-enabled) | on ||| || **Nethermind** | supported ✓ | off | on ||| || **Erigon** | [supported](https://github.com/erigontech/erigon/issues/18195) ✓ | on [(v.3.3.3+)](https://github.com/erigontech/erigon/issues/18195#issuecomment-3782497286) ✓ | on (off on unreleased main) ||| || **Reth** | supported ✓ | off (on [on main](https://github.com/paradigmxyz/reth/pull/23686 )) | on ||| || **Ethrex** | supported | on | on ||| Notes: Since Geth already has v5 on by default, we expect any client that turns on v5 support to find enough peers even if their v4 would be off. However, to keep the network well connected, also considering the time needed to roll out new versions, we need to leave a longer time window while both are supported. We can deprecate v4 during a hard-fork, where node operators are forced to update.