mirror of https://github.com/zcash/zips.git
140 lines
5.1 KiB
ReStructuredText
140 lines
5.1 KiB
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ZIP: 251
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Title: Deployment of the ${NU4} Network Upgrade
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Owners: Daira Hopwood <daira@electriccoin.co>
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Status: Draft
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Category: Consensus
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Created: 2020-02-28
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License: MIT
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Terminology
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===========
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The key words "MUST", "MUST NOT", "SHOULD", and "MAY" in this document are to be
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interpreted as described in RFC 2119. [#RFC2119]_
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The term "network upgrade" in this document is to be interpreted as described in
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ZIP 200. [#zip-0200]_
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The terms below are to be interpreted as follows:
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${NU4}
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Code-name for the fifth Zcash network upgrade, also known as Network Upgrade 4.
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Testnet
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The Zcash test network, as defined in [#protocol]_.
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Mainnet
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The Zcash production network, as defined in [#protocol]_.
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Abstract
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========
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This proposal defines the deployment of the ${NU4} network upgrade.
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Specification
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=============
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${NU4} deployment
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-----------------
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The primary sources of information about ${NU4} consensus protocol changes are:
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- The Zcash Protocol Specification [#protocol]_
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- ZIP 200: Network Upgrade Mechanism [#zip-0200]_
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- ZIP 207: Funding Streams [#zip-0207]_
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- ZIP 214: Consensus rules for a Zcash Development Fund [#zip-0214]_
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- ZIP 1014: Establishing a Dev Fund for ECC, ZF, and Major Grants [#zip-1014]_
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- TODO: other ZIPs
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The network handshake and peer management mechanisms defined in ZIP 201 [#zip-0201]_
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also apply to this upgrade.
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The following network upgrade constants [#zip-0200]_ are defined for the ${NU4}
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upgrade:
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CONSENSUS_BRANCH_ID
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``0xTODO``
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ACTIVATION_HEIGHT (${NU4})
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Testnet: TODO
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Mainnet: 1046400
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Nodes compatible with ${NU4} activation on testnet MUST advertise protocol version
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TODO or later. Nodes compatible with ${NU4} activation on mainnet MUST advertise
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protocol version TODO or later. The minimum peer protocol version that
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${NU4}-compatible nodes will connect to is 170002.
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Pre-${NU4} testnet nodes are defined as nodes on testnet advertising a protocol
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version less than TODO. Pre-${NU4} mainnet nodes are defined as nodes on mainnet
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advertising a protocol version less than TODO.
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For each network (testnet and mainnet), approximately 1.5 days (defined in terms of
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block height) before the corresponding ${NU4} activation height, nodes compatible
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with ${NU4} activation on that network will change the behaviour of their peer
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connection logic in order to prefer pre-${NU4} peers on that network for eviction
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from the set of peer connections::
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/**
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* The period before a network upgrade activates, where connections to upgrading peers are preferred (in blocks).
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* This was three days for upgrades up to and including Blossom, and is 1.5 days from Heartwood onward.
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*/
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static const int NETWORK_UPGRADE_PEER_PREFERENCE_BLOCK_PERIOD = 1728;
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The implementation is similar to that for Overwinter which was described in
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[#zip-0201]_.
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Once ${NU4} activates on testnet or mainnet, ${NU4} nodes SHOULD take steps to:
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- reject new connections from pre-${NU4} nodes on that network;
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- disconnect any existing connections to pre-${NU4} nodes on that network.
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Backward compatibility
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======================
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Prior to the network upgrade activating on each network, ${NU4} and pre-${NU4}
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nodes are compatible and can connect to each other. However, ${NU4} nodes will
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have a preference for connecting to other ${NU4} nodes, so pre-${NU4} nodes will
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gradually be disconnected in the run up to activation.
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Once the network upgrades, even though pre-${NU4} nodes can still accept the
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numerically larger protocol version used by ${NU4} as being valid, ${NU4} nodes
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will always disconnect peers using lower protocol versions.
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TODO: delete if inapplicable.
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Unlike Overwinter and Sapling, and like Blossom and Heartwood, ${NU4} does not
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define a new transaction version. ${NU4} transactions are therefore in the same
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v4 format as Sapling transactions; use the same version group ID, i.e. 0x892F2085
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as defined in [#protocol]_ section 7.1; and use the same transaction digest
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algorithm as defined in [#zip-0243]_. This does not imply that transactions are
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valid across the ${NU4} activation, since signatures MUST use the appropriate
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consensus branch ID. [#zip-0243]_
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Support in zcashd
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=================
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Support for ${NU4} on testnet will be implemented in ``zcashd`` version 3.1.0, which
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will advertise protocol version TODO. Support for ${NU4} on mainnet will be implemented
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in ``zcashd`` version 4.0.0, which will advertise protocol version TODO.
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References
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==========
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.. [#RFC2119] `Key words for use in RFCs to Indicate Requirement Levels <https://tools.ietf.org/html/rfc2119>`_
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.. [#protocol] `Zcash Protocol Specification, Version 2020.1.1 or later <protocol/protocol.pdf>`_
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.. [#zip-0200] `ZIP 200: Network Upgrade Activation Mechanism <zip-0200.rst>`_
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.. [#zip-0201] `ZIP 201: Network Peer Management for Overwinter <zip-0201.rst>`_
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.. [#zip-0207] `ZIP 208: Shorter Block Target Spacing <zip-0208.rst>`_
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.. [#zip-0214] `ZIP 214: Consensus rules for a Zcash Development Fund <zip-0214.rst>`_
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.. [#zip-0243] `ZIP 243: Transaction Signature Verification for Sapling <zip-0243.rst>`_
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.. [#zip-1014] `ZIP 1014: Establishing a Dev Fund for ECC, ZF, and Major Grants <zip-1014.rst>`_
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