Dell N3200-ON EMC Networking N-Series Switches CLI Reference Guide version 6.7 - Page 1904

Unicast RPF strict mode may be used on interfaces for which all packets received on an interface are guaranteed to originate from the subnet assigned to the interface. For example, a subnet composed only of end stations fulfills this requirement. Likewise, an access layer network or a branch office where there is only one path into and out of the network meets the requirement. In general, uRPF should be deployed on the downstream interfaces, preferably at the edge of the network. The further downstream uRPF is deployed, the more granularity the operator will have in identifying spoofed addresses. Command History Command introduced in version 6.6 firmware. Example console#configure console(config)#system urpf enable Warning! Enabling the system uRPF mode toggles the global routing mode in all VRFs, disrupting the L3 forwarding plane and control plane for few seconds. Enabling this mode also reduces the Route Table capacity. ip verify unicast source Use the ip verify unicast source command to enable loose uRPF checks on an interface. Use the no form of the command to disable uRPF checks on the interface. Syntax ip verify unicast source reachable-via {any | rx} [allow-default] no ip verify unicast source reachable-via • any-The uRPF verification mode is set to loose. In any mode, a check is performed to see if the source address is reachable in the routing table and when found the packet is forwarded. • rx-The uRPF verification mode is set to strict. In rx mode, a check is performed to see if the source address is reachable in the routing table via the same interface as to where the packet was received and when both these conditions are met the packet is forwarded. • allow-default-Include IP addresses not specifically contained in the routing table. Layer 3 Routing Commands 1904