Abstracting network state in Software Defined Networks (SDN) for rendezvous services

The Software Defined Network (SDN) model depends on abstractions to separate the control plane from the packet forwarding plane. Applications can interact with the control plane to receive a global network view, upon which they can operate. By having access to network topology information, applications can optimize decisions related to service rendezvous, service fulfillment, service placement and service removal. The network is in the best position to provide guidance to a broad class of applications, including peer-to-peer systems, Content Distribution Network (CDN), and datacenter applications. In all these use cases proximity matters as peers need to rendezvous with other peers and users need to rendezvous with the best cloud application or best CDN server. We maintain that a solution for such a rendezvous problem should be an intrinsic component of the emerging SDN model. A specific instance of a protocol that abstracts network topology is the Application Layer Traffic Optimization (ALTO) protocol. ALTO provides applications an abstract view of the network and thus enables applications to leverage a network without exposing the network provider's internal details or policies. We argue that ALTO provides a clean, mature, standards-based and powerful abstraction, which can be used by SDNs today to obtain network information for solving the rendezvous problem.