By Russ White
This chapter will appear in the forthcoming Cisco Press title, Inside Cisco IOS.
A multiprotocol router's primary purpose is, of course, to switch packets from one network segment to another. If the scheduler and memory manager are the router's software infrastructure, then the IOS switching architecture is the router's very foundation. The switching methods and structures that IOS employs essentially dictate how the router performs its primary task. So, as you can imagine, a great deal of effort has been put into designing and refining this important part of IOS.
In spite of all the fanfare, the packet-switching operation itself is fairly straightforward: A packet comes in, and then its destination ...