BGP (Border Gateway Protocol) handles route callback messages through the mechanism of Route Refresh. When a BGP speaker receives a route refresh request from a peer, it initiates a Route Refresh message. This message contains a request for the peer to send all of its BGP routing updates again, so that the local routing table can be synchronized with the peer’s routing table.
The Route Refresh message contains a set of parameters, including the address family, the requestor’s AS number, and a set of flags that control the behavior of the Route Refresh operation. When the peer receives the Route Refresh message, it sends all of its BGP routing updates again, using the same mechanism it would normally use to send updates to the local routing table.
The BGP speaker then updates its local routing table based on the updated routing information received in the Route Refresh message. This process allows the BGP speaker to correct any discrepancies that may have arisen as a result of stale or incomplete routing information.
Overall, the Route Refresh mechanism allows BGP speakers to efficiently update their routing tables with the latest routing information from their peers, without having to perform a full table redraw. This reduces the amount of network traffic and overhead required to maintain BGP routing tables, improving performance and stability of the network.
