Network Ingress Filtering: Defeating Denial of Service Attacks Which Employ IP Source Address Spoofing. P. Ferguson, D. Senie. May 2000. http://www.faqs.org/rfcs/rfc2827.html
PPP over Simple Data Link (SDL) using SONET/SDH with ATM-Like Framing J. Carlson, P. Langner, E. Hernandez-Valencia, et al. May 2000. http://www.faqs.org/rfcs/rfc2823.html