MENU

What is constantinoplefixblock?

November 25, 2019
0
199
0

If you have ever looked inside a blockchain genesis file, typically called genesis.json or in the case of a private network, privateNetworkGenesis.json, you will have seen lots of configuration parameters. Some are obvious but others a little more mysterious.

Take for example this genesis file for a private network:

{
  "config": {
      "constantinoplefixblock": 0,
      "ethash": {
        "fixeddifficulty": 1000
      },
       "chainID": 1981
   },
  "nonce": "0x42",
  "gasLimit": "0x1000000",
  "difficulty": "0x10000",
  "alloc": {
    "fe3b557e8fb62b89f4916b721be55ceb828dbd73": {
      "privateKey": "8f2a55949038a9610f50fb23b5883af3b4ecb3c3bb792cbcefbd1542c692be63",
      "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
      "balance": "0xad78ebc5ac6200000"
    },
    "f17f52151EbEF6C7334FAD080c5704D77216b732": {
      "privateKey": "ae6ae8e5ccbfb04590405997ee2d52d2b330726137b875053c36d94e974d162f",
      "comment": "private key and this comment are ignored.  In a real chain, the private key should NOT be stored",
      "balance": "90000000000000000000000"
    }
  }
}

Have you ever wondered what constantinoplefixblock is? It turns out that these are called “Milestone Blocks”. In a public network, these specifies the block at which the network changed protocols. For example,

"homesteadBlock": 1150000,
    "daoForkBlock": 1920000,
    "daoForkSupport": true,
    "eip150Block": 2463000,
    "eip150Hash": "0x2086799aeebeae135c246c65021c82b4e15a2c451340993aacfd2751886514f0",
    "eip155Block": 2675000,
    "eip158Block": 2675000,
    "byzantiumBlock": 4370000,
    "constantinopleBlock": 7280000,
    "constantinopleFixBlock": 7280000,
https://amberdata.io/blocks/7280000

In a private network though, the milestone block defines the protocol version for the network  so it is normally set to 0 (zero) meaning version 0 of the Constantinople protocol.

In other words, your chain won’t be hard-forking for these changes, so leave as 0 (zero).

Another interesting note in the private genesis file is fixeddifficulty which is used to specify a fixed difficulty in private networks using Ethash which overrides the difficulty field.

Leave a Comment!

Your email address will not be published. Required fields are marked *