Node discovery, channel discovery, and channel updates are broadcasted through gossip messages on the Lightning network. Rather than relying on a third-party to distribute information, Lightning relies on announcements containing information with network updates.
To support channel discovery, three gossip messages are supported. Peers in the network exchange channel_announcement
messages containing information regarding new channels between the two nodes. They can also exchange channel_update
messages, which update information about a channel. There can only be one valid channel_announcement
for any channel, but at least two channel_update
messages are expected.
To support node discovery, peers exchange node_announcement
messages, which supply additional information about the nodes. There may be multiple node_announcement
messages, in order to update the node information.
BOLT #7
[1] https://github.com/lightningnetwork/lightning-rfc/blob/master/07-routing-gossip.md