Important Network Functions Virtualization (NFV) scenarios such as ensuring middlebox fault tolerance or elasticity require redistribution of internal middlebox state. While many useful frameworks exist today for migrating/ cloning internal state, they require modifications to middlebox code to identify needed state. is process is tedious and manual, hindering the adoption of such frameworks. We present a framework-independent system, StateAlyzr, that embodies novel algorithms adapted from program analysis to provably and automatically identify all state that must be migrated/cloned to ensure consistent middlebox output in the face of redistribution. We find that StateAlyzr reducesman-hours required for code modification by nearly 20×. We apply State-Alyzr to four open source middleboxes and find its algorithms to be highly precise. We find that a large amount of, but not all, live state matters toward packet processing in these middleboxes. StateAlyzr's algorithms can reduce the amount of state that needs redistribution by 600- 8000× compared to naive schemes.
['Junaid Khalid', 'Aaron Gember-Jacobson', 'Roney Michael', 'Anubhavnidhi Abhashkumar', 'Aditya Akella']
Paving the way for NFV: simplifying middlebox modifications using StateAlyzr