VPP source of the tunnel interface should be configured, but we do not have this check
We cannot use sources that are not in the VPP

In this example, I used the wrong IP address, 192.0.2.222, when I should have used 192.0.2.1 as the source.

set interfaces ethernet eth1 address 192.0.2.1/24

set vpp settings interface eth1 driver 'dpdk'
set vpp interfaces gre gre2 remote '192.0.2.254'
set vpp interfaces gre gre2 source-address '192.0.2.222'

Additionally, source-address must not be equal to remote, and remote must not match the local interface address.

The same is true for the gre/ipip/vxlan