Cisco 10000 - Manual (Page 314)

13-12
Cisco 10000 Series Router Software Configuration Guide
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Chapter 13 Unicast Reverse Path Forwarding
Feature History for uRPF
Note Cisco 10000 series routers support both strict and loose mode uRPF for IPv4. However, for IPv6, the
router supports only strict uRPF.
The uRPF feature is described in the following topics:
• Feature History for uRPF, page 13-12
• Prerequisites for uRPF, page 13-12
• Restrictions for uRPF, page 13-12
• Configuring Unicast RPF, page 13-13
• Monitoring and Maintaining uRPF, page 13-14
• Configuration Examples of uRPF, page 13-16
Feature History for uRPF
Prerequisites for uRPF
Before you configure uRPF on a router, ensure that the interface supports IP addressing. For a broadband
interface, uRPF configurations must be added in the virtual template with all of the other
IP configurations.
Restrictions for uRPF
The uRPF feature in Cisco 10000 has the following restrictions:
• Clients should not be multihomed to the same router because multihoming defeats the purpose of
building a redundant service for the client.
• Customers must ensure that the packets flowing up the link (out to the Internet) match the route
advertised out the link. Otherwise, Unicast RPF filters those packets as malformed packets.
• Unicast RPF is available only for platform images that support CEF. Unicast RPF is supported in
Cisco IOS Releases 11.1(17)CC, 12.0, and later. It is not available in Cisco IOS Release 11.2 or
11.3.
• Unicast RPF is not supported by MPLS. It is supported only by IP traffic—IPv4 and IPv6. However,
IPv6 supports uRPF in strict mode only, with the allow-default option on.
• Unicast RPF does not support access control lists (ACLs).
• Unicast RPF requires Cisco express forwarding (CEF) to function properly on the router. For more
information about CEF, see the Cisco IOS Switching Services Configuration Guide.
Cisco IOS Release Description Required PRE
12.2(27)SBB This feature was introduced on the Cisco 10000 series
router with strict mode only. PRE2
12.2(33) SB This feature was integrated on Cisco 10000 with both strict
and loose modes for IPv4 traffic. PRE2, PRE3, and
PRE4