Hello Johnson
The vrf forwarding command can only be used under the interface configuration. You may be referring to the ip vrf forwarding command which can also be implemented in global configuration mode.
Cisco explains the difference like so:
In earlier Cisco IOS releases, you created a VRF to be applied only to an IPv4 address family (single-protocol VRF) by entering the ip vrf command. To activate the single-protocol VRF on an interface, you entered the ip vrf forwarding (interface configuration) command.
You can now define multiple address families under the same VRF or configure separate VRFs for each IPv4 or IPv6 address family by entering the vrf definition command. To activate the multiprotocol VRF on an interface, you enter the vrf forwarding command. A given VRF, identified by its name and a set of policies, can apply to both an IPv4 VPN and an IPv6 VPN at the same time. This VRF can be activated on a given interface, even though the routing and forwarding tables are different for the IPv4 and IPv6 protocols.
This has been taken from the following Cisco documentation:
I hope this has been helpful!
Laz