Create Customer Gateway Response from the service

The customer gateway is the appliance at your end of the VPN connection (compared to the VPN gateway, which is the device at the AWS side of the VPN connection). AWS might delete any customer gateway that you create with this operation if you leave it inactive for an extended period of time (inactive means that there's no VPN connection in use with the customer gateway). You must provide the Internet-routable IP address of the customer gateway's external interface. The IP address must be static and can't be behind a device performing network address translation (NAT). For device’s that use Border Gateway Protocal (BGP), you can also provide the device's Border Gateway Protocol (BGP) Autonomous System Number (ASN). You can use an existing ASN assigned to your network. If you don't have an ASN already, you can use a private ASN (in the 64512 - 65534 range). Amazon EC2 supports all 2-byte ASN numbers in the range of 1 - 65534, with the exception of 7224, which is reserved in US East, and 9059, which is reserved in EU West For more information about ASNs, go to the Wikipedia article - http://en.wikipedia.org/wiki/Autonomous_system_%28Internet%29.