BGP (Border Gateway Protocol) uses the longest prefix match algorithm to determine the most specific route to a destination network. When a BGP speaker receives an update from a peer advertising a new prefix, it will first check its own routing table to see if it already has a more specific route for that prefix. If it does, it will discard the advertisement from the peer.
If the BGP speaker does not have a more specific route, it will add the prefix to its routing table and advertise it to other BGP peers. Other BGP speakers will perform the same check to see if they have a more specific route and either discard the advertisement or add it to their routing table.
BGP also has the ability to perform route aggregation, which allows multiple prefixes to be combined into a single larger prefix. This helps to reduce the amount of routing information that needs to be exchanged between BGP speakers and can improve network performance. However, care must be taken to ensure that aggregation does not result in the loss of important routing information.
