Cisco Cisco IOS Software Release 12.0(13)S7
Unicast Reverse Path Forwarding in Strict Mode on the Cisco 12000 Series Internet Router
Prerequisites for Unicast Reverse Path Forwarding in Strict Mode on the Cisco 12000 Series Internet Router
2
Unicast Reverse Path Forwarding in Strict Mode on the Cisco 12000 Series Internet Router
OL-15426-01
•
•
•
•
•
•
•
•
Prerequisites for Unicast Reverse Path Forwarding in Strict
Mode on the Cisco 12000 Series Internet Router
Mode on the Cisco 12000 Series Internet Router
Note the following perquisites when you configure the Unicast RPF in Strict Mode feature on the
Cisco 12000 series Internet router.
Cisco 12000 series Internet router.
Supported Line Cards
Cisco IOS Release 12.0(33)S introduces support for the Unicast RPF in Strict Mode feature on all
IP Services Engine (ISE/Engine 3) and Engine 5 line cards in the Cisco 12000 series Internet router. For
information about the ISE and Engine 5 service interface processors (SIPs) and shared port adapters
(SPAs) supported on the Cisco 12000 series Internet router, refer to the
IP Services Engine (ISE/Engine 3) and Engine 5 line cards in the Cisco 12000 series Internet router. For
information about the ISE and Engine 5 service interface processors (SIPs) and shared port adapters
(SPAs) supported on the Cisco 12000 series Internet router, refer to the
Note
ISE and Engine 5 line cards already support Unicast RPF in loose
On the Cisco 12000 series Internet router, Unicast RPF is supported on other Engine types as follows:
•
Engine 4 line cards do not support Unicast RPF.
•
Engine 4+ line cards support Unicast RPF only in loose mode, but only on main interfaces.
Subinterfaces are not supported.
Subinterfaces are not supported.
•
Engine 6 line cards support Unicast RPF only in loose mode.
For information on the differences between loose and strict checking modes, see
.
Cisco Express Forwarding
The Unicast RPF in Strict Mode feature requires Cisco express forwarding (CEF) to function properly.
CEF is enabled, by default, on the Cisco 12000 series Internet router.
CEF is enabled, by default, on the Cisco 12000 series Internet router.
It is not necessary to configure an input interface for CEF switching because Unicast RPF has been
implemented as a search through the Forwarding Information Base (FIB) using the source IP address.
As long as CEF is running on the router, individual interfaces can be configured with other switching
modes. Unicast RPF is an input-side function that is enabled on an interface or subinterface that supports
any type of encapsulation and operates on IPv4 packets received by the router. CEF must be enabled
globally in the router—Unicast RPF does not work without CEF.
implemented as a search through the Forwarding Information Base (FIB) using the source IP address.
As long as CEF is running on the router, individual interfaces can be configured with other switching
modes. Unicast RPF is an input-side function that is enabled on an interface or subinterface that supports
any type of encapsulation and operates on IPv4 packets received by the router. CEF must be enabled
globally in the router—Unicast RPF does not work without CEF.