Hello Ajay
uRPF is a feature that checks the source address on a packet and compares it to the routing table. This means that by definition, uRPF will ONLY function on incoming packets. It can be enabled on any interface, but it will only operate on incoming packets on that interface. Packets that are exiting an interface have already gone through the routing table lookup and thus any uRPF operation cannot be applied to them.
Yes this is correct. According to Cisco:
An important consideration for deployment is that Cisco Express Forwarding switching must be enabled for Unicast RPF to function. This command has been enabled by default as of IOS version 12.2. If it is not enabled, administrators can enable it with the following global configuration command:
ip cef
CEF is enabled by default on most routers so it is not so much of a concern. However, you must confirm that CEF is enabled for uRPF to operate.
uRPF is not actually a routing operation. It essentially checks certain conditions and if those conditions are met, the packet can then be routed normally. It doesn’t come into play at all in load balancing or routing protocol path manipulation. In this sense, it functions more like an access list than a routing protocol. Once the conditions are met (either in loose or strict mode) the packet can then be routed normally using whatever routing protocol and whatever load balancing functionality has been configured. If they are not met, the packet is dropped before it even gets to the routing table lookup.
I hope this has been helpful!
Laz