1.2.2 Informative References
[RFC1661] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD 51, RFC 1661, July 1994, http://www.ietf.org/rfc/rfc1661.txt
[RFC2401] Kent, S. and Atkinson, R., "Security Architecture for the Internet Protocol", RFC 2401, November 1998, https://tools.ietf.org/html/rfc2401
[RFC768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, August 1980, http://www.rfc-editor.org/rfc/rfc768.txt