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Generic Routing Encapsulation over IPv4 networks (RFC1702)

IP.com Disclosure Number: IPCOM000002541D
Original Publication Date: 1994-Oct-01
Included in the Prior Art Database: 2019-Feb-12
Document File: 4 page(s) / 5K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Hanks: AUTHOR [+3]

Related Documents

10.17487/RFC1702: DOI

Abstract

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 memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 53% 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.

Hanks, Li, Farinacci & Traina [Page 1]

RFC 1702 GRE over IPv4 networks October 1994

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 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Address Family | SRE Offset | SRE Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | AS Number List ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IP as both delivery and payload protocol

When IP is encapsulated in IP, the TTL, TOS, and IP security options MAY be copied from the payload packet into the same fields in the delivery packet. The payload packet’s TTL MUST be decremented when the packet is deca...

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