Cloud Atlas: A Software Defined Networking Abstraction for Cloud to WAN Virtual Networking

One of the primary principles of Software Defined Networking (SDN) is that representing networks as a collection of simple abstractions implemented as an API - rather than as a collection of standardized and proprietary protocols and command line interfaces - will lead to networks that are easier to build and manage. Application of this principle has advanced furthest in cloud computing, where the OpenStack Quantum network service provides tenants in a data center with an abstraction of an enterprise LAN. The Quantum API implements a virtual network through a plug-in, which might in fact require protocols and command line interfaces to drive the physical hardware. However, existing OpenStack support for wide area connectivity is restricted to L3 IPsec and SSL VPNs which do not in general support quality of service (QoS). In this paper, we present Cloud Atlas, a SDN abstraction and API extending the Quantum virtual network into the WAN. Cloud Atlas is built on top of existing WAN network services (L1-, L2-, and L3VPNs) that do support QoS. Cloud Atlas makes these services available to OpenStack through a tight integration with Quantum. We discuss two prototypes we have built of Cloud Atlas, one based on command line scripts and one based on a network management system. We conclude the paper with some observations on applying the cloud service model to networking and the value of SDN abstractions in supporting such a service model.