With the following GRE tunnel configuration, how many bytes of GRE overhead does encapsulation add to the original data packet?
interface Tunnel0
ip address 1.1.1.1 255.255.255.252
tunnel source Ethernet0/0
tunnel destination 2.2.2.2
tunnel key 1234
A.
32 bytes
B.
24 bytes
C.
28 bytes
D.
20 bytes