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Last update: December 1, 2021

Adding nodes to the network

Adding new nodes to an existing network can range from a common occurrence to never happening. In public blockchains such as Ethereum Mainnet, new nodes continuously join and talk to the existing network. In permissioned blockchains, this may not happen as often, but it’s still an important task to achieve as your network evolves.

When adding new nodes to the network, it’s important to understand that the GoQuorum network and Tessera network are distinct and do not overlap in any way. Therefore, options applicable to one are not applicable to the other. In some cases, they may have their own options to achieve similar tasks, but must be specified separately.

Prerequisites

Adding GoQuorum nodes

Raft

Use the following API methods on an existing node to add, remove, and promote nodes in a Raft network:

If you are using permissioning or peer-to-peer discovery, see the extra options.

After addPeer or addLearner:

  1. Initialize the new node with the network’s genesis configuration:

    geth --datadir <NEW-NODE-DATA-DIRECTORY> init <GENESIS-FILE>
    

    Note

    Where you get the genesis file is dependent on the network. You may get it from an existing peer, a network operator, or somewhere else.

  2. Start the new GoQuorum node with the --raftjoinexisting and --raft command line options. Use the Raft ID returned by addPeer or addLearner as the argument for --raftjoinexisting.

    Example

     PRIVATE_CONFIG=ignore geth --datadir qdata/dd7 ... OTHER ARGS ... --raft --raftport 50407 --http.port 22006 --port 21006 --raftjoinexisting 7
    

    The new node is now up and running, and will start syncing the blockchain from existing peers. Once this has completed, it can send new transactions just as any other peer.

Important

For a Raft network to work, 51% of the peers must be up and running. We recommend having an odd number of at least 3 peers in a network.

IBFT, QBFT, and Clique

Adding a non-validator node to an IBFT, QBFT, or Clique network is simpler than adding a node to a Raft network, as it only needs to configure itself rather than be pre-allocated on the network (permissioning aside).

  1. Initialize the new node with the network’s genesis configuration:

    geth --datadir <NEW-NODE-DATA-DIRECTORY> init <GENESIS-FILE>
    

    Note

    Where you get the genesis file is dependent on the network. You may get it from an existing peer, a network operator, or somewhere else.

  2. If you are using permissioning or peer-to-peer discovery, see the extra options.

  3. Start the new node, pointing either to a bootnode or listing an existing peer in the static-nodes.json file. Once a connection is established, the node will start syncing the blockchain, after which transactions can be sent.

Adding a validator to an IBFT or QBFT network requires using the consensus APIs outlined in the IBFT tutorial and the QBFT tutorial.

Info

Validator nodes require the --mine command line option on startup, which enables mining, while non-validator nodes do not.

Extra options

Some options take effect regardless of the consensus mechanism used.

Permissioned nodes

If you have permissioning configured using the permissioned-nodes.json file, make sure this file is updated on all nodes before the new node is able to communicate with existing nodes.

You don’t need to restart any nodes for the changes to take effect.

Static node connections

If not using peer-to-peer node discovery (for example, you specify --nodiscover), then the node only makes connections to peers defined in the static-nodes.json file.

When adding a new node, configure static peers in its static-nodes.json file.

The more peers defined here, the better the network connectivity and fault tolerance.

Note

  • You don’t need to update the existing peers’ static nodes for the connection to be established, although it is good practice to do so.
  • You don’t need to specify every peer in your static nodes file if you do not wish to connect to every peer directly.

Peer-to-peer discovery

If using discovery, more options in addition to static nodes become available.

  • Any nodes connected to your peers, which at the start are your static peers, are discoverable by you; you connect to these nodes automatically.

  • You may specify bootnodes using the --bootnodes parameter. This takes a comma-separated list of enode URLs, similar to the static-nodes.json file. These act in the same way as static nodes, letting you connect to them and find out about other peers, who you then connect to.

Note

If you have discovery disabled, you won’t try to find other nodes to connect to, but others can still find and connect to you.

Adding Tessera nodes

Add a new Tessera node by ensuring you have one of the existing nodes listed in your Tessera peer list.

Peer configuration example

{
  "peers": [
    {
      "url": "http://existingpeer1.com:8080"
    }
  ]
}

From there, Tessera connects to that peer and discovers and connects to all the other Tessera nodes in the network.

Note

You may want to include multiple peers in the peer list in case any of them are offline/unreachable.

IP allowlisting

Tessera IP allowlisting (whitelisting) restricts connections in a way similar to using permissioned-nodes.json in GoQuorum.

If allowlisting is configured, only IP addresses/hostnames in your Tessera peer list can connect to you.

To add a new Tessera node with allowlisting enabled:

  1. Add the new peer to each of the existing nodes. You can run the following command without restarting an already running node:

    java -jar tessera.jar admin -configfile /path/to/existing-node-config.json -addpeer http://newpeer.com:8080
    
  2. Start the new peer, setting the peers configuration to mirror the existing network.

    Peers configuration example

    {
      "peers": [
        {
          "url": "http://existingpeer1.com:8080"
        },
        {
          "url": "http://existingpeer2.com:8080"
        },
        {
          "url": "http://existingpeer3.com:8080"
        }
      ]
    }
    

    The new node now allows incoming connections from the existing peers, and existing peers allow incoming connections from the new peer.

Discovery

You can disable Tessera discovery to have Tessera only allow keys that are owned by a node in its peer list to be available to the users.

This means that if Tessera finds any keys owned by a node not in its peer list, those keys are discarded and private transactions cannot be sent to that public key.

Notes

  • This does not affect incoming transactions. Someone not in your peer list can still send transactions to your node, unless you also enable the IP allowlist option.
  • IP allowlisting blocks communications between nodes, whereas disabling discovery only affects which public keys Tessera keeps track of.

To add a new Tessera node with discovery disabled:

  1. Add the new peer to each of the existing nodes. You can run the following command without restarting an already running node:

    java -jar tessera.jar admin -configfile /path/to/existing-node-config.json -addpeer http://newpeer.com:8080
    
  2. Start the new peer, setting the peers configuration to mirror the existing network.

    Peers configuration example

    {
      "peers": [
        {
          "url": "http://existingpeer1.com:8080"
        },
        {
          "url": "http://existingpeer2.com:8080"
        },
        {
          "url": "http://existingpeer3.com:8080"
        }
      ]
    }
    

    The new node now records public keys belonging to the existing peers, and existing peers record public keys belonging to the new peer. This allows private transactions to be sent both directions.

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