Cisco Catalyst 4500 Series Software Configuration Guide

36-5
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
Chapter 36 Configuring Cisco Express Forwarding
Catalyst 4500 Series Switch Implementation of CEF
Figure 36-2 Hardware and Software Switching Components
The Integrated Switching Engine performs inter-VLAN routing in hardware. The CPU subsystem
software supports Layer 3 interfaces to VLANs that use Subnetwork Access Protocol (SNAP)
encapsulation. The CPU subsystem software also supports generic routing encapsulation (GRE) tunnels.
Hardware Switching
• Hardware switching is the normal operation for switches with supervisor engines.
• Beginning in Cisco IOS XE Release 3.7.1E, GRE tunnels are supported on the hardware on
Catalyst 4500 series switches. When GRE is configured without tunnel options, packets are
hardware-switched. Otherwise, packets are switched in the software.
Software Switching
Software switching occurs when traffic cannot be processed in hardware. The following types of
exception packets are processed in software at a much slower rate:
• Packets that use IP header options
Note Packets that use TCP header options are switched in hardware because they do not affect the
forwarding decision.
• Packets that have an expiring IP time-to-live (TTL) counter
• Packets that are forwarded to a tunnel interface.
Note When GRE tunnels are configured without tunnel options, packets are hardware-switched.
• Packets that arrive with non-supported encapsulation types
• Packets that are routed to an interface with non-supported encapsulation types
Integrated Switching Engine
CPU Subsystem
GRE
tunnel
L3 physical
interface
Router
L3 interfaces
L2 switchports
68127
VLAN1
Gig 1/1
VLAN2
GRE
tunnel

Cisco Catalyst 4500 Series Specifications

General

Series	Catalyst 4500 Series
Category	Switch
Layer Support	Layer 2, Layer 3
Form Factor	Modular chassis
Stackable	No
Chassis Slots	3, 6, 7, 10
Power Supply Options	AC, DC
Redundancy	Power supply, Supervisor engine
Network Management	Cisco IOS Software CLI, SNMP, Cisco Prime Infrastructure
Features	Security, QoS
Port Density	Up to 384 ports per chassis
Security Features	802.1X, ACLs, DHCP Snooping, Dynamic ARP Inspection, IP Source Guard
Supervisor Engine	8-E