A fast compiler for NetKAT

Abstract

High-level programming languages play a key role in a growing number of networking platforms, streamlining application development and enabling precise formal reasoning about network behavior. Unfortunately, current compilers only handle "local" programs that specify behavior in terms of hop-by-hop forwarding behavior, or modest extensions such as simple paths. To encode richer "global" behaviors, programmers must add extra state-something that is tricky to get right and makes programs harder to write and maintain. Making matters worse, existing compilers can take tens of minutes to generate the forwarding state for the network, even on relatively small inputs. This forces programmers to waste time working around performance issues or even revert to using hardware-level APIs. This paper presents a new compiler for the NetKAT language that handles rich features including regular paths and virtual networks, and yet is several orders of magnitude faster than previous compilers. The compiler uses symbolic automata to calculate the extra state needed to implement "global" programs, and an intermediate representation based on binary decision diagrams to dramatically improve performance. We describe the design and implementation of three essential compiler stages: from virtual programs (which specify behavior in terms of virtual topologies) to global programs (which specify network-wide behavior in terms of physical topologies), from global programs to local programs (which specify behavior in terms of single-switch behavior), and from local programs to hardware-level forwarding tables. We present results from experiments on real-world benchmarks that quantify performance in terms of compilation time and forwarding table size.

Scalable verification of probabilistic networks

“…model checking to represent large state spaces compactly. A variant called Forwarding Decision Diagrams (FDDs) [45] was previously developed specifically for the networking domain, but only supported deterministic behavior. In this work, we extended FDDs to probabilistic FDDs.…”

Cantor meets Scott: semantic foundations for probabilistic networks

“…While loops are useful for implementing higher level abstractions such as network virtualization in NetKAT (Smolka et al 2015).…”

Event-driven network programming

“…The functionality described above is also provided by standard NetKAT [35]. The key distinguishing feature of our Stateful NetKAT is a special global vector-valued variable called state, which allows the programmer to represent a collection of NetKAT programs.…”

“…The function shown in Figure 5 gives the standard NetKAT program p k corresponding to each value k of the state vector (for conciseness, we only show the non-trivial cases). We can use the NetKAT compiler [35] to generate forwarding tables (i.e. configurations) corresponding to these, which we denote C( p k ).…”

“…The Frenetic project [10] [27] [11] allows higher-level specification of network policies. Other related projects like Merlin [36] and NetKAT [35] [4] provide high-level languages/tools to compile such programs to network configurations. Works such as Maple [37] and FlowLog [31] seek to address the dynamic aspect of network programming.…”