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.