Route reflector

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A route reflector is a technique for interconnecting Border Gateway Protocol (BGP) routers, inside an autonomous system, to improve scalability.[1] Route reflection improves iBGP scalability by removing the need to have a full mesh of BGP sessions among all routers in the AS; it allows the creation of hierarchies of routers, with full mesh only on the "route servers" in each "cluster" of BGP speakers.

Basic cluster structure

Fault tolerance

Hierarchies of clusters

Pathologies of route reflection

[2]

Route reflectors and confederations

While both techniques allow increased iBGP scalability, they do it in different ways, and indeed the two techniques may be used in the same AS. Confederations give more policy control than do route reflectors, but with greater complexity.

References

  1. BGP Route Reflection: An Alternative to Full Mesh Internal BGP (IBGP) (RFC 4456)
  2. Border Gateway Protocol (BGP) Persistent Route Oscillation Condition (RFC 3345)