Cisco Cisco IOS Software Release 12.0(2b) Guide De Dépannage

Introduction
 Prerequisites
      Requirements
      Components Used
      Conventions

What Is Cisco IOS Switching?
Verification Steps
 Understand CEF Punts
 Related Information

Cisco IOS® Software supports several mechanisms to facilitate the forwarding of traffic with minimal delay
and high throughput. This document explains how to determine which Cisco IOS switching or forwarding
path your packets take.

Note: This document discusses process switching, fast switching, and Cisco Express Forwarding (CEF) only.

Readers of this document should be knowledgeable of these topics:

Cisco IOS Software

• 

Cisco 1600, 2500, and 3600 Series platforms

• 

This document is not restricted to specific software and hardware versions.

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Cisco IOS switching defines the packet flow through the router. More specifically, it determines how quickly
the packet can be forwarded through the router, and also in which physical buffers the packets are stored.

During the history of Cisco IOS, multiple switching methods have been developed. Some methods are
supported only on particular platforms. CEF is the latest switching method. When CEF is enabled globally
(default behavior), the ip route−cache cef interface specific command is also enabled. This command ensures
CEF switching is done for packets that enter this interface. Occasionally, if needed to disable CEF on one