Hub and Spoke BGP: Leveraging multicast to improve wireless inter-domain routing

Satellite payloads and wireless cell/broadband towers are being designed and deployed to simultaneously provide backbone network connectivity for hundreds to thousands of end-user networks. Hence, large wireless "hub and spoke" networks are created. In order to allow user-networks to utilize their own IP address space, hub nodes must distribute user routes throughout the hub and spoke network utilizing a common network routing protocol such as Border Gateway Protocol (BGP). RFC 4271 compliant BGP, also known as BGPv4, is not optimized to take advantage of the multicast capabilities of a wireless channel. In this paper we show that given a wireless hub and spoke network running BGP with N spokes, system wide bandwidth savings from O(N²) to O(N) can be gained through multicasting the BGP routing messages. We will first present an analytical model with equations that explain our hypothesis, and then introduce a multicast version of BGP called Hub and Spoke BGP. We present a comparison study of large scale hub and spoke emulations utilizing both standard BGP and our multicast-capable version, validating the bandwidth savings.