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The hearbeat protocol's main purpose is to notify to other peers that the node is still active and running. This information may be relevant for managing a list of active peers.

The heartbeat protocol is defined by using Ping and Pong messages and it allows to implement different strategies to react to peer inactivity.

For example:

  • If during a period of time (e.g. 30 minutes) a peer has not transmitted any messages, it will send a heartbeat as Ping message.
  • If during a period of time (e.g. 90 minutes) no message has been received by a remote peer, the local node will assume that the connection has been closed.
         NodeA                          NodeB
           +                              +
           |             PING             |
           |             PONG             |
           |                              |
           +                              +

Ping and Pong messages

The Ping message confirms that the connection is still valid. The Pong message is sent in response to a Ping message. Both contain only 1 field:

Field Type Description
nonce fixed64 A random number