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Generic Routing Encapsulation (GRE) (RFC1701)

IP.com Disclosure Number: IPCOM000002540D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 7 page(s) / 14K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Hanks: AUTHOR [+4]

Abstract

This document specifies a protocol for performing encapsulation of an arbitrary network layer protocol over another arbitrary network layer protocol.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 21% of the total text.

Network Working Group S. Hanks

Request for Comments: 1701 NetSmiths, Ltd.

Category: Informational T. Li

D. Farinacci

P. Traina

cisco Systems

October 1994

Generic Routing Encapsulation (GRE)

Status of this Memo

This memo provides information for the Internet community. This memo

does not specify an Internet standard of any kind. Distribution of

this memo is unlimited.

Abstract

This document specifies a protocol for performing encapsulation of an

arbitrary network layer protocol over another arbitrary network layer

protocol.

Introduction

A number of different proposals [RFC 1234, RFC 1226] currently exist

for the encapsulation of one protocol over another protocol. Other

types of encapsulations [RFC 1241, SDRP, RFC 1479] have been proposed

for transporting IP over IP for policy purposes. This memo describes

a protocol which is very similar to, but is more general than, the

above proposals. In attempting to be more general, many protocol

specific nuances have been ignored. The result is that this proposal

is may be less suitable for a situation where a specific "X over Y"

encapsulation has been described. It is the attempt of this protocol

to provide a simple, general purpose mechanism which is reduces the

problem of encapsulation from its current O(n^2) problem to a more

manageable state. This proposal also attempts to provide a

lightweight encapsulation for use in policy based routing. This memo

explicitly does not address the issue of when a packet should be

encapsulated. This memo acknowledges, but does not address problems

with mutual encapsulation [RFC 1326].

In the most general case, a system has a packet that needs to be

encapsulated and routed. We will call this the payload packet. The

payload is first encapsulated in a GRE packet, which possibly also

includes a route. The resulting GRE packet can then be encapsulated

in some other protocol and then forwarded. We will call this outer

protocol the delivery protocol. The algorithms for processing this

packet are discussed later.

Overall packet

The entire encapsulated packet would then have the form:

---------------------------------

| |

| Delivery Header |

| |

---------------------------------

| |

| GRE Header |

| |

---------------------------------

...