Site to Site VPN for Beginners. The two sites are able to access the internet and having static Public IP. the equation is the sites need to access each other resources securely over the web. A small example is as below: Router 1: Router1#sh running-config Building configuration... Current configuration : 1303 bytes ! version 12.4 no service timestamps log datetime msec no service timestamps debug datetime msec no service password-encryption ! hostname Router1 ! ! ! ! ! ! ! ! ip cef no ipv6 cef ! ! ! ! crypto isakmp policy 1 encr aes authentication pre-share group 5 lifetime 1800 ! crypto isakmp key nightread3r address 122.1.1.2 ! ! crypto ipsec security-association lifetime seconds 1800 ! crypto ipsec transform-set t-set esp-aes esp-sha-hmac ! crypto map test 10 ipsec-isakmp set peer 122.1.1.2 set security-association lifetime seconds 1800 set transform-set t-set match address 101 ! ! ! ! ! ! spanning-tree