Chapter 23 Configuring Layer 3 Interfaces; Overview Of Layer 3 Interfaces - Cisco 4500M Software Manual

Configuring Layer 3 Interfaces
This chapter describes the Layer 3 interfaces on a Catalyst 4500 series switch. It also provides
guidelines, procedures, and configuration examples.
This chapter includes the following major sections:
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For complete syntax and usage information for the switch commands used in this chapter, refer to the
Note
Catalyst 4500 Series Switch Cisco IOS Command Reference and related publications at
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/index.htm.

Overview of Layer 3 Interfaces

This section contains the following subsections:
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The Catalyst 4500 series switch supports Layer 3 interfaces with the Cisco IOS IP and IP routing
protocols. Layer 3, the network layer, is primarily responsible for the routing of data in packets across
logical internetwork paths.
Layer 2, the data link layer, contains the protocols that control the physical layer (Layer 1) and how data
is framed before being transmitted on the medium. The Layer 2 function of filtering and forwarding data
in frames between two segments on a LAN is known as bridging.
The Catalyst 4500 series switch supports two types of Layer 3 interfaces. The logical Layer 3 VLAN
interfaces integrate the functions of routing and bridging. The physical Layer 3 interfaces allow the
Catalyst 4500 series switch to be configured like a traditional router.
OL-6696-01
Overview of Layer 3 Interfaces, page 23-1
Configuration Guidelines, page 23-3
Configuring Logical Layer 3 VLAN Interfaces, page 23-3
Configuring Physical Layer 3 Interfaces, page 23-4
Logical Layer 3 VLAN Interfaces, page 23-2
Physical Layer 3 Interfaces, page 23-2
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Software Configuration Guide—Release 12.2(25)EW
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