RouteReflectoren

RouteReflectoren, in English known as route reflectors, are a mechanism within the Border Gateway Protocol (BGP) used to simplify iBGP full-mesh peering inside a single autonomous system. Their main purpose is to reduce the number of iBGP sessions required between routers while ensuring all routers learn the same routes.

A route reflector designates certain routers as route reflectors and others as clients. iBGP routes learned from a client are reflected by the route reflector to other clients, enabling reachability across the network without every router peering with every other router. Routes learned from non-clients or from another route reflector may also be propagated to clients according to configured policies. The next-hop handling is configurable; a common setting is to preserve the original next-hop, while a route reflector may be configured to rewrite next-hops (for example, using next-hop-self) to improve reachability.

Deployment patterns include single route reflectors for small to medium networks, and multi-reflector clusters for larger environments to provide redundancy and scalability. In large networks, route reflectors are often organized into hierarchical or clustered designs, sometimes combined with BGP confederations to limit scope and policy complexity. Operators typically apply filtering and route-map policies to control which routes are reflected and to manage routing policies consistently across the cluster.

Key considerations include avoiding suboptimal routing and potential routing loops, ensuring redundancy to prevent a single point of failure, and managing policy consistency across reflectors. Route reflectors are commonly used in enterprise networks, Internet service providers, and at Internet exchange points in conjunction with or as an alternative to traditional full-mesh iBGP peering.