220 likes | 338 Views
A Difference Resolution Approach to Compressing Access Control Lists. James Daly, Alex Liu, Eric Torng Michigan State University INFOCOM 2013. Motivation. Classifiers used for many applications Packet Forwarding Firewalls Quality of Service Classifiers are growing New threats
E N D
A Difference Resolution Approach to Compressing Access Control Lists James Daly, Alex Liu, Eric Torng Michigan State University INFOCOM 2013
Motivation • Classifiers used for many applications • Packet Forwarding • Firewalls • Quality of Service • Classifiers are growing • New threats • New services
Motivation • Classifier compression is an important problem • Device imposed rule limits • NetScreen-100 allows only 733 rules • Simplifies rule management • DIFANE [Yu et al. SIGCOMM 2010]
Background Packet: [2, 4]
Classifier Definition • Classifier : list of rules • Tupleof d intervals over finite, discrete fields • Decision (accept, deny, physical port number, etc.) • Only first matching rule applies • Classifiers equivalent if they give the same result for all inputs
Problem Definition • Problem • Input: classifier • Output: smallest equivalent classifier • NP-Hard 6
Prior Work • Redundancy Removal [eg. Liu and Gouda. DBSec 2005] • Iterated Strip Rule [Applegate et al. SODA 2007] • Only two dimensions • Approximation guarantee: O(min(n1/3, Opt1/2)) • Firewall Compressor [Liu et al. INFOCOM 2008] • Optimal weighted 1-D case • Works on higher dimensions
Diplomat • Three parts • Base solver for the last row • Firewall Compressor for 1D case • Diplomat otherwise • Resolver • Given two rows identify and resolve differences • Merge rows together into one • Scheduler • Find best order to resolve rows
Scheduling • Multi-row resolver: greedy schedule • Single-row resolver: dynamic programming schedule
Dynamic Schedule Upper Bound Remaining Row Source Row Lower Bound
Results • Comparison of Firewall Compressor and Diplomat on 40 real-life classifiers • Divided into sets based on size • Diplomat requires 30% fewer rules on largest sets • 2-D bounds: O(min(n1/3, Opt1/2)) Mean Compression Ratio
Conclusion • Diplomat offers significant improvements over Firewall Compressor because it focuses on the differences between rows • Results are most pronounced on larger classifiers • Can guarantee approximation bound for 2-D classifiers