Generic Routing Encapsulation (GRE) Tunnel Configuration

Router Branch
===========

Router>enable
Router#configure terminal
Router(config)#hostname Branch
Branch(config)#interface tunnel0
Branch(config-if)#tunnel mode gre ip
Branch(config-if)#ip address 192.168.1.101 255.255.255.224
Branch(config-if)#tunnel source 10.165.201.1
Branch(config-if)#tunnel destination 172.16.1.1
Branch(config-if)#exit
Branch(config)#exit
Branch#copy running-config startup-config

Router HQ
========

Router>enable
Router#configure terminal
Router(config)#hostname HQ
HQ(config)#interface tunnel0
HQ(config-if)#tunnel mode gre ip
HQ(config-if)#ip address 192.168.1.102 255.255.255.224
HQ(config-if)#tunnel source 172.16.1.1
HQ(config-if)#tunnel destination 10.165.201.1
HQ(config-if)#exit
HQ(config)#exit
HQ#copy running-config startup-config

Verifying a GRE Tunnel
==================
Router#show interface tunnel0
Router#show ip interface brief
Router#show ip interface brief | include tunnel
Router#show ip route