Chapter 1. Evolution of the Cisco IOS System Architecture

Cisco IOS is the original brand name for Cisco's routing software. As Cisco's technology offerings expanded, IOS diversified and became a series of tightly linked internetworking software products. Although its brand name might still equate to routing software, the continuing evolution of IOS has seen the software migrate to support LAN, ATM, xDSL, and WAN switches as well as provide important functionality for network applications such as network security, network management, DHCP, and web scaling services. This chapter defines Cisco IOS, the evolution of its architecture, and the goals and benefits of this architecture. This background information helps explain the formation and evolution of the various Cisco IOS software releases described in this book.