Browse Prior Art Database

Generic Routing Encapsulation over IPv4 networks (RFC1702)

IP.com Disclosure Number: IPCOM000002541D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 3 page(s) / 7K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Hanks: AUTHOR [+4]

Abstract

In an earlier memo [RFC 1701], we described GRE, a mechanism for encapsulating arbitrary packets within an arbitrary transport protocol. This is a companion memo which describes the use of GRE with IP. This memo addresses the case of using IP as the delivery protocol or the payload protocol and the special case of IP as both the delivery and payload. This memo also describes using IP addresses and autonomous system numbers as part of a GRE source route.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 44% of the total text.

Network Working Group S. Hanks

Request for Comments: 1702 NetSmiths, Ltd.

Category: Informational T. Li

D. Farinacci

P. Traina

cisco Systems

October 1994

Generic Routing Encapsulation over IPv4 networks

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.

Introduction

In an earlier memo [RFC 1701], we described GRE, a mechanism for

encapsulating arbitrary packets within an arbitrary transport

protocol. This is a companion memo which describes the use of GRE

with IP. This memo addresses the case of using IP as the delivery

protocol or the payload protocol and the special case of IP as both

the delivery and payload. This memo also describes using IP

addresses and autonomous system numbers as part of a GRE source

route.

IP as a delivery protocol

GRE packets which are encapsulated within IP will use IP protocol

type 47.

IP as a payload protocol

IP packets will be encapsulated with a Protocol Type field of 0x800.

For the Address Family value of 0x800, the Routing Information field

will consist of a list of IP addresses and indicates an IP source

route. The first octet of the Routing Information field constitute a

8 bit integer offset from the start of the Source Route Entry (SRE),

called the SRE Offset. The SRE Offset indicates the first octet of

the next IP address. The SRE Length field consists of the total

length of the IP Address List in octets.

This has the form:

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| Address Family | SRE Offset | SRE Length |

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

| IP Address List ...

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

For the Address Family value of 0xfffe, the Routing Information field

will consist of a list of Autonomous System numbers and indicates an

AS source route. The third octet of the Routing Information field

contains an 8 bit unsigned integer offset from the start of the

Source Route Entry (SRE), called the SRE Offset. The SRE Offset

indicates the first octet of the next AS number. THe SRE Length

field consists of the total length of the AS Number list in octets.

0 1 2 3

0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4...