Communications designers are faced with designing higher speed communications equipment that can accommodate a wide variety of real-time and non-real time information delivery. Increasing complexity, high availability, and time to market pressures require new technologies that address these issues. Network processors are a hot technology that promises wire speed performance, increased capacity and shorter development efforts. This lecture investigates the impact network processor technology has on the existing communications software baseline and looks at key software technologies to make optimal use of a network processor in a design. The lecture will provide an overview of what a network processor is and look in slightly more detail on the Intel IXP1200 network processor as an example. Then focus will shift to inherent properties of a real-time operating system that take advantage of network processor technology, and new development tool requirements. Finally, the key to network processors is the wire speed packet processing. The lecture will provide an overview of the microcode concept and discuss how the microcode provides a bridge between the network processor and operating system protocol stacks to enable wire speed performance. Finally, a network processor design for ethernet to ATM bridge router will be broken down and discussed how the software is impacted on a network processor design.