 the fundamental constraints in the formulation of the efficient insertion/deletion problem is TCAM's Prefix Length Ordering (PLO) constraint. The PLO constraint in a TCAM has nothing to do with policies toward Middle East issues. It is just an easy-to-remember abbreviation. PLO is a mathematical problem formulation of how to best structure the CAM in such a way that pre- fix sorting remains invariant. The PLO concept is based on the observation that prefixes of the same length can be stored in any order inside their correct block. Among the many algorithms proposed to tackle the reorganization of the TCAM-based lookup and forwarding table, the most preeminent are the PLO_OPT, CAO_OPT, and L-Solution algorithms. L is the number of possible prefix lengths; for IPv4 addresses, it is equal to 32. These algorithms are discussed in detail and analyzed in the article "Fast Update on Ternary-CAMs for Packet Lookups and Classification" written by Devavrat Shah and Pankaj Gupta. 5. Devavrat Shah and Pankaj Gupta, "Fast Updates on Ternary-CAMs for Packet Lookups and Classification," IEEE Micro 21, no. 1 (January-February 2001). Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. CLASSIFICATION PROCESSORS CLASSIFICATION PROCESSORS 245 In order to empty one space inside the memory bank, the L-Solution algorithm takes no more than L memory shifts, whereas the PLO constraint applied to the same problem reduces that requirement by half to almost L/2 memory shifts per table-entry update. CAO stands for Chain Ancestor Ordering constraint. This is a means of relaxing the exact storage constraints applied to some types of maximal-length chains. It has very important effects on the over- all classification performance of the algorithm. We will just mention that the ratio of updating per- formance between both the worst-case and the typical (mean) number of memory w