Chapter overview: * explains the channel graph, and how it’s modified+verified
Relevant questions to answer: * Gossip announcements: * How does a peer announce a new channel to the network? * How do nodes verify a channel announcement? Why should they verify one in the first place? * How does a node control how a payment is routed through its channel? * What knobs exist for a node to set in their channel updates? * How often are channel updates sent? * How does a node update its node in the channel graph? Do we we need to verify this? * How quickly does an update propagate? * What are "zombie" channels? Why do they matter? * Channel graph syncing: * What are the various ways a node can sync the channel graph? * Which is the most efficient? * What is the "gossip query" system? * Does a node need to keep up with all gossip updates? Does this change if they’re a routing node or mobile client? * Protocol Extensions via Feature Bits and TLV: * How can the channel graph be upgraded using feature bits and TLV fields? * How does a receiver signal that they can accept MPP/AMP payments?