Summary
This TIP describes the global protocol parameters for the IOTA protocol.
Motivation
Various other protocol TIPs rely on certain constants that need to be defined for an actual implementations of nodes or other applications using the protocol. This TIP serves as a single document to provide these parameters. It also serves as a historical record of protocol parameter changes.
Detailed design
| Name | Value | Description |
|---|---|---|
| Network Name | "iota-mainnet" | Identifier string of the network. Its hash it used for the Network ID field in transactions. |
| Protocol Version | 2 | Protocol version currently used by the network |
| Max Block Length | 32768 | Maximum length of a block in bytes. Limits Tangle storage size and communication costs. |
| Max Parents Count | 8 | Maximum number of parents of a block. |
| Min PoW Score | 1500.0 | Minimum PoW score for blocks to pass syntactic validation. |
| First Milestone Index | 1 | First valid milestone index. |
| Max IOTA Supply | 4600000000000000 | Total amount of IOTA coins in circulation. |
| Max Inputs Count | 128 | Maximum number of inputs in a transaction payload. |
| Max Outputs Count | 128 | Maximum number of outputs in a transaction payload. |
| Max Native Token Count | 64 | Maximum number of different native tokens that can be referenced in one transaction. |
| Max Tag Length | 64 | Maximum length of a Tag field in bytes. |
| Max Metadata Length | 8192 | Maximum length of a Metadata field in bytes. |
| VByte Cost | 250 | Minimum amount of IOTA that need to be deposited per vbyte of an output. |
| SLIP-44 Coin Type (decimal) | 4218 | Registered coin type (decimal) for usage in level 2 of BIP44 described in chapter "Coin type". |
SLIP-44 Path Component (coin_type') | 0x8000107a | Registered path component for usage in level 2 of BIP44 described in chapter "Coin type". |
| Bech32 Human-Readable Part | iota | HRP prefix to use for Bech32 encoded IOTA addresses. (e.g. iota1zzy3drvj6zugek60srqwhqctkjldx3qle5yuvapj) |
| Bech32 Human-Readable Part (Test) | atoi | HRP prefix to use for Bech32 encoded IOTA addresses on test- or development networks. (e.g. atoi1zzy3drvj6zugek60srqwhqctkjldx3qle5fhvhm6) |
Rationale for parameter choices
Transaction and block limits
The block parameter Max Block Length and Max Parent Count, as well as the transaction parameters Max Inputs Count, Max Outputs Count, Max Native Token Count, Max Tag Length and Max Metadata Length govern the block and transaction validity. Their values have been chosen to ensure functionality of the protocol within constrained resource restrictions. Furthermore, choosing more conservatives values here is preferable as increasing such limits can always been done preserving backward compatibility.
Dust protection
The VByte Cost is the core parameter of the dust protection. The reasoning behind its value is explained in TIP-19 Dust Protection.
Copyright
Copyright and related rights waived via CC0.