Specifications

IP Switching Commands
ipv6 verify unicast reverse-path
ISW-81
Cisco IOS IP Switching Command Reference
May 2008
ipv6 verify unicast reverse-path
To enable Unicast Reverse Path Forwarding (Unicast RPF) for IPv6, use the ipv6 verify unicast
reverse-path command in interface configuration mode. To disable Unicast RPF, use the no form of this
command.
ipv6 verify unicast reverse-path [access-list name]
no ipv6 verify unicast reverse-path [access-list name]
Syntax Description
Command Default Unicast RPF is disabled.
Command Modes Interface configuration
Command History
Usage Guidelines The ipv6 verify unicast reverse-path command is used to enable Unicast RPF for IPv6 in strict
checking mode. The Unicast RPF for IPv6 feature requires that Cisco Express Forwarding for IPv6
(CEFv6) is enabled on the router.
Note Beginning in Cisco IOS Release 12.0(31)S, the Cisco 12000 series Internet router supports both the
ipv6
verify unicast reverse-path and ipv6 verify unicast source reachable-via rx commands to enable
Unicast RPF to be compatible with the Cisco IOS Release 12.3T and 12.2S software trains.
Use the ipv6 verify unicast reverse-path command to mitigate problems caused by malformed or
forged (spoofed) IP source addresses that pass through a router. Malformed or forged source addresses
can indicate denial-of-service (DoS) attacks based on source IP address spoofing.
When Unicast RPF is enabled on an interface, the router examines all packets received on that interface.
The router checks to make sure that the source IPv6 address appears in the routing table and that it is
reachable by a path through the interface on which the packet was received. Unicast RPF is an input
feature and is applied only on the input interface of a router at the upstream end of a connection.
access-list name (Optional) Specifies the name of the access list.
Note This keyword and argument are not supported on the Cisco 12000
series Internet router.
Release Modification
12.2(13)T This command was introduced.
12.2(14)S This command was integrated into Cisco IOS Release 12.2(14)S.
12.0(31)S This command was integrated into Cisco IOS Release 12.0(31)S and
introduced on the 10G Engine 5 SPA Interface Processor in the Cisco 12000
series Internet router.
12.2(28)SB This command was integrated into Cisco IOS Release 12.2(28)SB.