http://www.rfc-editor.org/rfc/rfc1180.txt
RFC 1180: TCP/IP tutorial, T.J. Socolofsky, C.J. Kale1991-01-01T23:00:00-00:00This RFC is a tutorial on the TCP-IP protocol suite, focusing particularly on the steps in forwarding an IP datagram from source host to destination host through a router. It does not specify an Internet standard.