Updated 2019-11-25

Network ID and Chain ID

Ethereum networks have a network ID and a chain ID. The network ID defaults to the chain ID specified in the genesis file.

Chain ID in Genesis File

{
  "config": {
    "ethash": {
    },
     "chainID": 1981
  },
  ...
}

For most networks including MainNet and the public testnets, the network ID and the chain ID are the same and are specified in the genesis file.

The network ID and chain ID are automatically defined by Besu when connecting to networks specified using the --network option:

Network Chain Chain ID Network ID Type
mainnet ETH 1 1 Production
ropsten ETH 3 3 Test
rinkeby ETH 4 4 Test
goerli ETH 5 5 Test
dev ETH 2018 2018 Development
classic ETC 61 1 Production
mordor ETC 63 7 Test
kotti ETC 6 6 Test

When using the --network=dev or --genesis-file options, you can override the network ID using the --network-id option.