Routing Table Exchange Algorithm

Routing table exchange algorithm

Every node on the network stores its own copy of the Routing Graph . nearcore exchanges this graph in two steps. When a connection is set up, the two nodes do a full sync. After that, they send only incremental updates.

After a handshake on a TIER2 connection completes, each node sends one SyncRoutingTable message to the other node. The message holds a RoutingTableUpdate with all edges that the node knows. After that, a node broadcasts only edges that it has not seen before, also in SyncRoutingTable messages. Up to nearcore 2.14.0, these messages also carry account announcements. TIER1 and TIER3 connections do not exchange the routing table. See the Synchronization section of the network specification and the PeerMessage listing.

Removed proposal

An earlier proposal described a partial exchange that sends only the difference between two routing tables. It used Inverse Bloom Filters and a RoutingSyncV2 message. nearcore had a prototype of it behind a nightly-only build feature. nearcore 1.28.0 removed the prototype, and it was never active on mainnet or testnet. The RoutingSyncV2 message does not exist on the network.