IS-IS Network Design Solutions

Cisco Packet-Switching Mechanisms

At the beginning of this chapter, the distinction between IP forwarding and IP routing is discussed, and the separation between the forwarding plane and the control plane in modern routers is mentioned. As noted, the control plane is associated with the route processor, which runs the routing protocols. As illustrated in Figure 1-9, actual forwarding of packets is performed by dedicated hardware-based forwarding engines, which are mainly implemented in application-specific integrated circuits (ASICs). ASIC-based forwarding engines are necessary to achieve high forwarding rates. CPU-based forwarding is relatively slow; however, over the years, Cisco has developed various methods for speeding up the lookup process ...