Configuring Unicast Reverse Path Forwarding - Cisco Catalyst 4500 series Administration Manual

Configuring Unicast Reverse Path Forwarding

This chapter describes the Unicast Reverse Path Forwarding (Unicast RPF) feature. The Unicast RPF
feature helps to mitigate problems that are caused by malformed or forged IP source addresses that are
passing through a switch.
For a complete description of the Unicast RPF commands in this chapter, refer to the chapter "Unicast
Reverse Path Forwarding Commands" of the Cisco IOS Security Command Reference. To locate
documentation of other commands that appear in this chapter, use the command reference master index
or search online.
To identify the hardware platform or software image information associated with a feature, use the
Feature Navigator on Cisco.com to search for information about the feature or refer to the software
release notes for a specific release. For more information, see the "Identifying Supported Platforms"
section in the chapter "Using Cisco IOS Software."
This chapter includes the following sections:
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Note For complete syntax and usage information for the switch commands used in this chapter, see the Cisco
Catalyst 4500 Series Switch Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/hw/switches/ps4324/index.html
If a command is not in the Catalyst 4500 Series Switch Command Reference, you can locate it in the
Cisco IOS library. See the Cisco IOS Command Reference and related publications at this location:
http://www.cisco.com/en/US/products/ps6350/index.html
About Unicast Reverse Path Forwarding
The Unicast RPF feature helps to mitigate problems that are caused by the introduction of malformed or
forged (spoofed) IP source addresses into a network by discarding IP packets that lack a verifiable IP
source address. For example, a number of common types of denial-of-service (DoS) attacks, including
Smurf and Tribal Flood Network (TFN), can take advantage of forged or rapidly changing source IP
OL_28731-01
About Unicast Reverse Path Forwarding, page 36-1
Unicast RPF Configuration Tasks, page 36-9
Monitoring and Maintaining Unicast RPF, page 36-11
Unicast RPF Configuration Example: Inbound and Outbound Filters, page 36-12
C H A P T E R
Software Configuration Guide—Release IOS XE 3.6.0E and IOS 15.2(2)E
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36-1