What does the term 'route reflector' mean in BGP?

The term 'route reflector' in BGP refers to a device that reflects BGP routes within the same Autonomous System (AS). Route reflectors are used to reduce the number of BGP peer connections needed in large networks, thus simplifying the BGP topology while maintaining efficiency.

In a typical BGP setup without route reflectors, all routers within the same AS need to establish peer connections with every other router (full mesh). This can become impractical as the number of routers increases. By using a route reflector, a router can receive route information from its clients and then reflect that information to other clients. This hierarchical arrangement allows for a more scalable design, as not every router needs to connect to every other router directly.

The other options deal with different BGP concepts. Optimizing path selection involves various attributes and policies but is not what a route reflector specifically does. Route aggregation is a method used to combine routes but does not define route reflectors. Additionally, the term does not refer to a type of BGP state; rather, it is a functional role within the BGP architecture. This distinction clarifies the specific function of a route reflector in facilitating efficient routing information exchange within an Autonomous System.