R1(config)# interface tunnel 0
R1(config-if)# description Tunnel to Branch B
R1(config-if)# ip address 172.16.0.1 255.255.255.0
R1(config-if)# ip mtu 1400
R1(config-if)# ip tcp adjust-mss 1360
R1(config-if)# ip ospf network broadcast
R1(config-if)# tunnel source 1.1.1.10
R1(config-if)# tunnel destination 2.2.2.10
R1(config-if)# tunnel protection ipsec profile Protect-GRE