RFC 1622 (rfc1622) - Page 2 of 16
Pip Header Processing
Alternative Format: Original Text Document
RFC 1622 Pip Header Processing May 1994
Conventions
All functions in this specification are mandatory.
1. Introduction
Pip is an internet protocol intended as the replacement for IP
version 4. Pip is a general purpose internet protocol, designed to
handle all forseeable internet protocol requirements. This
specification defines the Pip header processing for Routers and
Hosts.
The design of Pip is fundamentally different from that of previous
internetwork protocols. Pip is designed to be as general as
possible, but without significantly compromising performance.
Because of Pip's generality, it can handle forseeable routing and
addressing requirements. It is hoped that it will be able to handle
most if not all future routing and addressing requirements.
There are many detailed aspects of Pip that provide this generality
that are not discussed here. It is useful, however, to mention one
general aspect. That is, Pip strives to remove as much "functional
semantics" from the base specification as possible. Pip defines a
packet header and forwarding rules that can include many different
functional semantics (that is, routing, addressing, and flow
paradigms). Therefore, the reader may often find him or herself
asking "But how do you do foo with Pip?" The answer to this sort of
question belongs in companion documents to the basic Pip spec.
Pip can be thought of as a mechanism for triggering actions in hosts
and routers, just as a machine language can be thought of as a
mechanism for triggering actions in CPUs. The machine language has
no functional semantics outside of the specific actions it triggers
(move this register, write that memory location, etc.). But, the
machine language is a very powerful tool upon which functional
semantics are built. Likewise, Pip is a powerful tool upon which
routing, addressing, and flow functions can be built.
Francis