Abstract

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In a number of environments, a component external to a network is called upon to perform computations based on the network topology and current state of the connections within the network, including Traffic Engineering (TE) information. This is information typically distributed by IGP routing protocols within the network.This document describes a mechanism by which link-state and TE information can be collected from networks and shared with external components using the BGP routing protocol. This is achieved using a new BGP Network Layer Reachability Information (NLRI) encoding format. The mechanism is applicable to physical and virtual IGP links. The mechanism described is subject to policy control.

The threat of commoditization poses a real challenge for service providers. While the end-to-end principle is often paraphrased as "dumb network, smart end-systems", the original paper makes a more subtle argument about appropriate distribution of functionality among endpoints and intermediate systems. Functions may be implemented in the network for performance reasons, and when they offer value to a wide range of applications without inhibiting the correct operation of applications that do not need these functions. In this context, we describe a prototype platform for experimentation with novel, useful functions "inside" the network. This programmable platform allows service providers to innovate quickly and to deploy new functions within the network when it makes sense. By implementing the platform as an overlay, service providers can assist those applications that benefit from added functions such as caching and streaming support, without interfering with the correct and efficient operation of other applications that do not need them. Service providers can also leverage their detailed topological knowledge and ability to control network resources, features that would be difficult for conventional overlays. Programmability of the platform enables features to be extended or composed with other pieces of software, by either the service providers or third parties.