https://certificationsolution.com/mtu-has-been-configured-on-the-underlying-physical-topology-and-no-mtu-command-has-been-configured-on-the-tunnel-interfaces-what-happens-when-a-1500-byte-ipv4-packet-traverses-the-gre-tunnel-from-ho/
MTU has been configured on the underlying physical topology, and no MTU command has been configured on the tunnel interfaces.<br> What happens when a 1500-byte IPv4 packet traverses the GRE tunnel from host X to host Y, assuming the DF bit is cleared?