Building an Ethereum Consortium Chain: A Step-by-Step Guide

Introduction to Proof-of-Authority (PoA) Chains

When should you create your own PoA test chain?

For corporate intranets or isolated networks where blockchain synchronization is impossible
To reduce block confirmation times during testing
To avoid compatibility issues with test networks like testrpc

Key characteristics of PoA chains:

Unlike Proof-of-Work (PoW) that requires computational puzzles, PoA relies on pre-approved Authority nodes to generate blocks
Flexible configuration of Authority node quantities
Customizable block generation intervals (e.g., 5 seconds after transaction receipt)
Compatible with standard Ethereum nodes for transactions and smart contracts

Getting Started with Parity Wallet

Installation Guide

Download Parity Ethereum Client:
Official website: Parity Ethereum
Latest release: GitHub v2.2.9

Ubuntu Installation:

# Install Linuxbrew
ruby -e "$(wget -O- https://raw.github.com/Homebrew/linuxbrew/go/install)"
apt install linuxbrew-wrapper

# Add Parity repository
brew tap paritytech/paritytech

# Install latest stable version
brew install parity --stable

Configuring Your Consortium Chain

Genesis Block Specification

Create demo-spec.json with this template:

{
  "name": "DemoPoA",
  "engine": {
    "authorityRound": {
      "params": {
        "stepDuration": "5",
        "validators": {
          "list": []
        }
      }
    }
  },
  "params": {
    "gasLimitBoundDivisor": "0x0400",
    "networkID": "0x2323"
  },
  "genesis": {
    "difficulty": "0x20000",
    "gasLimit": "0x5B8D80"
  }
}

Key parameters:

stepDuration: 5-second block intervals
validators: Initially empty (to be populated later)

Node Configuration Files

Node 0 (node0.toml):

[parity]
chain = "demo-spec.json"
base_path = "parity0"
[network]
port = 30300
[rpc]
port = 8540
apis = ["web3", "eth", "net", "personal", "parity"]

Node 1 (node1.toml):

[parity]
chain = "demo-spec.json"
base_path = "parity1"
[network]
port = 30301
[rpc]
port = 8541
apis = ["web3", "eth", "net", "personal", "parity"]

👉 Explore advanced node configuration options

Account Setup and Network Deployment

Creating Authority Accounts

Initialize accounts through Parity UI:
- Access Node 0 at http://localhost:8180
- Create Authority account with passphrase "node0"
- Create user account with initial balance

Update demo-spec.json:

"validators": {
  "list": [
    "0x00Bd138...77C9e",
    "0x00F9B30...b180"
  ]
},
"accounts": {
  "0x0064B09...3EcC": {
    "balance": "10000000000000000000000"
  }
}

Launching Authority Nodes

Add mining configuration to TOML files:

[account]
password = ["node.pwds"]
[mining]
engine_signer = "0x00Bd138...77C9e" # Authority address
reseal_on_txs = "none"

Start nodes with:

parity --config node0.toml
parity --config node1.toml

Network Operations and Transactions

Connecting Nodes

Retrieve Node 0's enode:
```
{"method":"parity_enode","params":[]}
```

Connect from Node 1:

{"method":"parity_addReservedPeer","params":["enode://...@IP:30300"]}

Sending Test Transactions

Use the user account (funded with 10,000 ETH) to:

Transfer between accounts
Deploy test contracts
Verify block generation timing

👉 Learn about consortium chain use cases

FAQ Section

Q1: What's the difference between PoA and private chains?
A: PoA chains use designated validators instead of mining, offering faster block times and deterministic finality.

Q2: How many Authority nodes are recommended?
A: For testing, 2-3 nodes suffice. Production environments typically use 7-15 for fault tolerance.

Q3: Can I connect MetaMask to my PoA chain?
A: Yes, configure MetaMask with your node's RPC endpoint (e.g., http://localhost:8540).

Q4: How do I add more nodes later?
A: Update the validators list in demo-spec.json and restart all nodes with the new configuration.

Q5: What's the gas price on PoA chains?
A: Typically set to 0 or minimal values since there's no mining competition.

Q6: How do I monitor node performance?
A: Use Parity's built-in UI or tools like Grafana with the trace API enabled.