As we know that URPF have two work modes:
l Strict mode
l Loose mode
How can I choose the work mode?
Strict mode
In strict URPF mode, a data packet can pass the URPF check only when the forwarding table contains a matching entry and the outbound interface of the entry matches the inbound interface of the packet.
Loose mode
In loose URPF mode, a packet can pass the URPF check as long as there is a route with the destination address that is the source address of the packet, regardless of whether the outbound interface of the route and the inbound interface of the packet match.
we can configure the loose mode on the link which is connect between the backbone interface, because there one routing maybe have multi-link.
For the interface which connect the end user, if there only have single link, we can enable the strict mode.
