ZIP: 253
Title: Deployment of the NU6 Network Upgrade
Owners: Arya <arya@zfnd.org>
Status: Implemented (zcashd and zebrad)
Category: Consensus / Network
Created: 2024-07-17
License: MIT
Discussions-To: <https://github.com/zcash/zips/issues/806>

Terminology

The key word “MUST” in this document are to be interpreted as described in BCP 14 ¹ when, and only when, they appear in all capitals.

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

The terms “Testnet” and “Mainnet” are to be interpreted as described in section 3.12 of the Zcash Protocol Specification ³.

Abstract

This proposal defines the deployment of the NU6 network upgrade.

Specification

NU6 deployment

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

• The Zcash Protocol Specification ⁴.
• ZIP 200: Network Upgrade Mechanism ².
• ZIP 236: Blocks should balance exactly ⁵.
• ZIP 1015: Block Reward Allocation for Non-Direct Development Funding ⁶.
• ZIP 2001: Lockbox Funding Streams ⁷.

The network handshake and peer management mechanisms defined in ZIP 201 ⁸ also apply to this upgrade.

The following ZIPs have been updated in varying degrees to take into account NU6:

• ZIP 207: Funding Streams ⁹.
• ZIP 214: Consensus rules for a Zcash Development Fund ¹⁰.

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

CONSENSUS_BRANCH_ID

0xC8E71055

ACTIVATION_HEIGHT (NU6)

Testnet: 2976000

Mainnet: 2726400

MIN_NETWORK_PROTOCOL_VERSION (NU6)

Testnet: 170110

Mainnet: 170120

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

Backward compatibility

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

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

NU6 does not define a new transaction version or impose a new minimum transaction version. NU6 transactions are therefore in the same v4 or v5 formats as NU5 transactions. This does not imply that transactions are valid across the NU6 activation, since signatures MUST use the appropriate consensus branch ID.

References