Multicast BGP with SDN control plane

Intra-domain Border Gateway Protocol (BGP) scalability has been tackled by introducing Route Reflectors, which have been universally adopted, but creating a new set of challanges: lack of route diversity, potential correctness failures both at the control and data plane (i.e. routing loops), and iBGP messaging duplication. The problem is exacerbated by popular enterprise services such as L2 and L3 Virtual Private Networks, for which Multiprotocol BGP is a major building block. The stress imposed on backbone routers by the diversity and scale of services is one of the reasons for the emergence of the Software Defined Networking (SDN) paradigm, seeking to liberate routing hardware from the burden of service implementation, transferring the complexity to controller software. In this article we examine a new approach for iBGP information dissemination, which i) is equivalent to full-mesh, maintaining correctness and route diversity, and ii) also scales in terms of session management. The former objective is accomplished by substitution of route reflection by per-ASBR (Autonomous System Border Router) BGP message multicasting, while the latter is assured by delegation of multicast tree maintenance complexity to SDN.