 that offer a powerful programmability similar to traditional off-the-shelf CPUs but with a performance level that approaches that of ASICs for packet- processing applications. By adopting network processors in their designs, network equipment manu- facturers can obtain the sought-after high performance, while retaining their system flexibility and decreasing their development cycle. So how do network processors do this? As we will find out when we examine various representa- tive architectures later in the book, network processors provide specialized circuitry and appropriate architectural structures coupled with fine-tuned low-level instruction sets that coordinate a highly opti- mized performance for packet-processing functions compared to that expected from off-the-shelf CPUs. Network processors contain microengines that are wired to perform all the generic packet- processing functions exceedingly well at wire speed. In addition, they also usually embed a major pro- grammable module, usually a tailor-made RISC CPUs (and sometimes more than just one) that allows the execution of real-time operating systems, handshake communications with other parts of a larger network device, and SO on. THE VALUE PROPOSITION OF NETWORK PROCESSORS Based on what we have said, the benefits of adopting network processors in the new designs are as follows: Shorter time to market Instead of the 18 months it takes to design an ASIC, a vendor using a network processor platform can realistically expect to complete the development cycle of the packet-processing part of a major network device product within 6 months. Of course, a whole sys- tem development project will need more than 6 months to be developed. The actual length of time depends on the nature of the system and the engineering resources invested in tackling it. The net- work-processor-based product's performance will most likely be almost as fast as that of an ASIC- based one, while the programmability of the network processor will allow the flexibility of offering new featu