A Fast Compiler for NetKAT

In the past few years, high-level programming languages have played a key role in several networking platforms, by providing abstractions that streamline application development. Unfortunately, current compilers can take tens of minutes to generate forwarding state for even relatively small networks. This forces programmers to either work around performance issues or revert to using lower-level APIs.

In this talk, we first present a new compiler for NetKAT (a network programming language) that is two orders of magnitude faster than existing systems. Our key insight is a new intermediate representation based on a variant of binary decision diagrams that can represent network programs compactly and supports fast, algebraic manipulation. We argue that our compiler scales to large networks using a diverse set of benchmarks.

In addition to speed, our new intermediate representation lets us build a powerful new abstraction for network programming. Existing languages provide constructs for programming individual switches, which forces programmers to specify whole-network behavior on a switch-by-switch basis. For the first time, we can compile programs that syntactically represent sets of end-to-end paths through the network.  To do so, our compiler automatically inserts stateful operations (e.g., VLAN tagging) to distinguish overlapping paths from each other.

Finally, we present a very general implementation of network virtualization that leverages our ability to compile end-to-end paths.  The key insight is to give packets two locations--physical and virtual--and synthesize a program that moves packets along physical paths to account for hops in the virtual network. We show that different synthesis strategies can be used to implement global requirements, such as shortest paths, load-balancing, and so on.

Arjun Guha is an assistant professor of Computer Science at UMass Amherst. He enjoys tackling problems in systems using the tools and principles of programming languages. Apart from network programming, he has worked on Web security and system configuration languages. He received a PhD in Computer Science from Brown University in 2012 and a BA in Computer Science from Grinnell College in 2006.