A Widely Deployed Solution to the Generic Routing Encapsulation (GRE) Fragmentation Problem
RFC 7588
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RFC - Informational
(July 2015; No errata)
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Last updated |
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2015-10-14
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draft-bonica-intarea-gre-mtu
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IETF
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WG state
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Submitted to IESG for Publication
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Document shepherd |
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Suresh Krishnan
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(last changed 2015-03-15)
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RFC 7588 (Informational)
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Yes
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Brian Haberman
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Internet Engineering Task Force (IETF) R. Bonica
Request for Comments: 7588 Juniper Networks
Category: Informational C. Pignataro
ISSN: 2070-1721 Cisco Systems
J. Touch
USC/ISI
July 2015
A Widely Deployed Solution to the Generic Routing Encapsulation (GRE)
Fragmentation Problem
Abstract
This memo describes how many vendors have solved the Generic Routing
Encapsulation (GRE) fragmentation problem. The solution described
herein is configurable. It is widely deployed on the Internet in its
default configuration.
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7588.
Bonica, et al. Informational [Page 1]
RFC 7588 GRE Fragmentation July 2015
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 5
2. Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. RFC 4459 Solutions . . . . . . . . . . . . . . . . . . . 5
2.2. A Widely Deployed Solution . . . . . . . . . . . . . . . 5
3. Implementation Details . . . . . . . . . . . . . . . . . . . 6
3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. GRE MTU (GMTU) Estimation and Discovery . . . . . . . . . 6
3.3. GRE Ingress Node Procedures . . . . . . . . . . . . . . . 7
3.3.1. Procedures Affecting the GRE Payload . . . . . . . . 7
3.3.2. Procedures Affecting the GRE Deliver Header . . . . . 8
3.4. GRE Egress Node Procedures . . . . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Normative References . . . . . . . . . . . . . . . . . . 10
5.2. Informative References . . . . . . . . . . . . . . . . . 11
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
Bonica, et al. Informational [Page 2]
RFC 7588 GRE Fragmentation July 2015
1. Introduction
Generic Routing Encapsulation (GRE) [RFC2784] [RFC2890] can be used
to carry any network-layer protocol over any network-layer protocol.
GRE has been implemented by many vendors and is widely deployed in
the Internet.
The GRE specification does not describe fragmentation procedures.
Lacking guidance from the specification, vendors have developed
implementation-specific fragmentation solutions. A GRE tunnel will
operate correctly only if its ingress and egress nodes support
compatible fragmentation solutions. [RFC4459] describes several
fragmentation solutions and evaluates their relative merits.
This memo reviews the fragmentation solutions presented in [RFC4459].
It also describes how many vendors have solved the GRE fragmentation
problem. The solution described herein is configurable and has been
widely deployed in its default configuration.
This memo addresses point-to-point unicast GRE tunnels that carry
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