Use of IPv6 requires a run-time key because IPsec uses cryptography. Because IPsec was previously only supported on IPv6 networks, the IPv6 product key is also required for IPsec, even if the configuration only uses IPv4. The run-time keys for IPv6 and IPsec are included with the IOE Encryption Option, which is separately orderable at no charge. The MCP run-time keys should be installed during normal MCP software installation.