RFC 1853 (rfc1853) - Page 2 of 8
IP in IP Tunneling
Alternative Format: Original Text Document
RFC 1853 IP Tunnelling October 1995 1. Introduction The IP in IP encapsulation Protocol/Payload number 4 [RFC-1700] has long been used to bridge portions of the Internet which have disjoint capabilities or policies. This document describes implementation techniques used for many years by the Amateur Packet Radio network for joining a large mobile network, and also by early implementations of IP Security protocols. Use of IP in IP encapsulation differs from later tunneling techniques (for example, protocol numbers 98 [RFC-1241], 94 [IDM91a], 53 [swIPe], and 47 [RFC-1701]) in that it does not insert its own special glue header between IP headers. Instead, the original unadorned IP Header is retained, and simply wrapped in another standard IP header. This information applies principally to encapsulation of IP version 4. Other IP versions will be described in separate documents. Simpson Informational



