 ports configurations that have access to multiple logical tables using 32- to 512-bit-wide keys, support Best Match searches, and even possess a patented feature called weight array that allows easier table management and, more specifically, the handling of low-cost insertions. The policy engine can be used to implement layer 4 switching, such as packet prioritization based on some layer 4 information. It allows functionality as dynamic port assignment in applications such as voice over IP (VoIP). It can also be used to expedite the mainline network-processor packet examination and classification code. The coprocessor interconnection bus can be extended off-chip, thereby facilitating a broader spectrum of products with potentially different search requirements such as web switching via Uniform Resource Locator (URL) matching or Internet core routing. The AMCC approach involves two other important characteristics: the single programming image that the architecture provides to the designer and the company's ability to offer ancillary chips such as traffic managers, switch fabrics, and SO on, which create an almost complete design of a whole sys- tem with minimal hardware effort. We discuss the single programming image in the section "Developing Software for the nP Family of Network Processors." We cover the topic of the company's ability to offer ancillary chips in a sep- arate section, "Systems Considerations When Designing with AMCC nP Family NPUs." 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. AMCC nPTM FAMILY OF NETWORK PROCESSORS 96 NETWORK PROCESSORS DEVELOPING SOFTWARE FOR THE NP FAMILY OF NETWORK PROCESSORS Figure 6.3 shows the cleanly layered structure of nPsoftTM Services, which is essentially a software services architecture. The company's approach has the advantage of only requiring the addition parts necessary for the overall d