Dell N3200-ON Networking N-Series Switches CLI Reference Guide version 6.8.0 - Page 1918

Command Mode Global Configuration mode User Guidelines This command enables the uRPF feature in hardware. When the uRPF check is enabled, the route table is checked for source and destination IP match in parallel. For this reason, the route table capacity is reduced once this feature is enabled. A message to this effect is displayed to the user. This command enables the mode for both v4 and v6. This command also causes the IP routing to be disabled and re-enabled if it was enabled prior to issuing the command. uRPF supports two modes of source IP check: • Strict mode - The path to the source IP address must be through the SAME interface as that on which the packet arrived. • Loose mode - The path to the source IP address can be through any interface on the device. The allowed default option, when used in conjunction with loose mode, considers the default route (if present) in the routing table if the specified prefix is not found. The allowed default option, when used in conjunction with strict mode, passes the uRPF check only if the packet arrives on the interface(s) where the default route is learned. uRPF checks do not work for multicast packets or for link-local IPv6 addresses. uRPF checks are not performed on a BOOTP/DHCP packet (SIP is 0.0.0.0 and DIP is FF.FF.FF.FF). uRPF logs missed uRPF checks in the system log. Unicast RPF loose mode may be used on an uplink interface which has a default route associated with it. For example, a single-homed environment with symmetric routing meets this requirement. Layer 3 Routing Commands 1918