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Software Configuration Guide—Release 12.2(25)EW
OL-6696-01
Chapter 1 Product Overview
Layer 3 Software Features
Layer 3 Software Features
A Layer 3 switch is a high-performance switch that has been optimized for a campus LAN or an intranet,
and it provides both wirespeed Ethernet routing and switching services. Layer 3 switching improves
network performance with two software functions—route processing and intelligent network services.
Compared to conventional software-based switches, Layer 3 switches process more packets faster; they
do so by using application-specific integrated circuit (ASIC) hardware instead of microprocessor-based
engines.
The following subsections describe the key Layer 3 switching software features on the Catalyst 4500
series switch:
• CEF, page 1-6
• HSRP, page 1-6
• IP Routing Protocols, page 1-6
• Multicast Services, page 1-9
• Policy-Based Routing, page 1-10
• Unidirectional Link Routing, page 1-10
• VRF-lite, page 1-10
CEF
Cisco Express Forwarding (CEF) is an advanced Layer 3 IP-switching technology. CEF optimizes
network performance and scalability in networks with large and dynamic traffic patterns, such as the
Internet, and on networks that use intensive web-based applications or interactive sessions. Although
you can use CEF in any part of a network, it is designed for high-performance, highly resilient Layer 3
IP-backbone switching.
For information on configuring CEF, see Chapter 24, “Configuring Cisco Express Forwarding.”
HSRP
The Hot Standby Router Protocol (HSRP) provides high network availability by routing IP traffic from
hosts on Ethernet networks without relying on the availability of any single Layer 3 switch. This feature
is particularly useful for hosts that do not support a router discovery protocol and do not have the
functionality to switch to a new router when their selected router reloads or loses power.
For information on configuring HSRP, refer to the following URL:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/ip_c/ipcprt1/1cdip.htm
IP Routing Protocols
The following routing protocols are supported on the Catalyst 4500 series switch:
• RIP
• OSPF
• IS-IS
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