Deployment of the NU6.1 Network Upgrade

Preamble

ZIP

255

Title

Deployment of the NU6.1 Network Upgrade

Owners

Daira-Emma Hopwood

Credits

Arya

Status

Final

Category

Consensus / Network

Created

2025-05-06

License

MIT

Discussions-To

https://github.com/zcash/zips/issues/1011

Terminology

The key word "MUST" in this document is to be interpreted as described in BCP 14 ¹ when, and only when, it appears in all capitals.

The term "network upgrade" in this document is to be interpreted as described in ZIP 200. ²

The character § is used when referring to sections of the Zcash Protocol Specification. ³

The terms "Mainnet" and "Testnet" are to be interpreted as described in § 3.12 ‘Mainnet and Testnet’. ⁴

Abstract

This proposal defines the deployment of the NU6.1 network upgrade.

Specification

NU6.1 deployment

The primary sources of information about NU6.1 consensus protocol changes are:

• The Zcash Protocol Specification ³.
• ZIP 200: Network Upgrade Mechanism ².
• ZIP 271: Deferred Dev Fund Lockbox Disbursement ⁵.
• ZIP 1016: Community And Coinholder Funding Model ⁶.

The network handshake and peer management mechanisms defined in ZIP 201 ⁷ also apply to this upgrade.

The following network upgrade constants ² are defined for the NU6.1 upgrade:

CONSENSUS_BRANCH_ID : 0x4DEC4DF0

ACTIVATION_HEIGHT (NU6.1) : Testnet: 3536500 : Mainnet: 3146400

MIN_NETWORK_PROTOCOL_VERSION (NU6.1) : Testnet: 170130 : Mainnet: 170140

For each network (Testnet and Mainnet), nodes compatible with NU6.1 activation on that network MUST advertise a network protocol version that is greater than or equal to the MIN_NETWORK_PROTOCOL_VERSION (NU6.1) for that activation.

Backward compatibility

Prior to the network upgrade activating on each network, NU6.1 and pre-NU6.1 nodes are compatible and can connect to each other. However, NU6.1 nodes will have a preference for connecting to other NU6.1 nodes, so pre-NU6.1 nodes will gradually be disconnected in the run up to activation.

Once the network upgrades, even though pre-NU6.1 nodes can still accept the numerically larger protocol version used by NU6.1 as being valid, NU6.1 nodes will always disconnect peers using lower protocol versions.

References

Footnotes

1. Information on BCP 14 — "RFC 2119: Key words for use in RFCs to Indicate Requirement Levels" and "RFC 8174: Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words" ↩

2. ZIP 200: Network Upgrade Mechanism ↩ ↩² ↩³

3. Zcash Protocol Specification, Version 2025.6.0 or later ↩ ↩²

4. Zcash Protocol Specification, Version 2025.6.0 [NU6.1 proposal]. Section 3.12: Mainnet and Testnet ↩

5. ZIP 271: Deferred Dev Fund Lockbox Disbursement ↩

6. ZIP 1016: Community and Coinholder Funding Model ↩

7. ZIP 201: Network Peer Management for Overwinter ↩