Generic Routing Encapsulation (GRE) Key Extension for Mobile IPv4
RFC 6245

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Internet Engineering Task Force (IETF)                         P. Yegani
Request for Comments: 6245                              Juniper Networks
Category: Standards Track                                       K. Leung
ISSN: 2070-1721                                            Cisco Systems
                                                                 A. Lior
                                                     Bridgewater Systems
                                                            K. Chowdhury
                                                               J. Navali
                                                           Cisco Systems
                                                                May 2011

   Generic Routing Encapsulation (GRE) Key Extension for Mobile IPv4

Abstract

   The Generic Routing Encapsulation (GRE) specification contains a Key
   field, which MAY contain a value that is used to identify a
   particular GRE data stream.  This specification defines a new Mobile
   IP extension that is used to exchange the value to be used in the GRE
   Key field.  This extension further allows the Mobility Agents to set
   up the necessary protocol interfaces prior to receiving the mobile
   node traffic.  The new extension allows a Foreign Agent to request
   GRE tunneling without disturbing the Home Agent behavior specified
   for Mobile IPv4.  GRE tunneling with the Key field allows the
   operators to have home networks that consist of multiple Virtual
   Private Networks (VPNs), which may have overlapping home addresses.
   When the tuple <Care of Address, Home Address, and Home Agent
   Address> is the same across multiple subscriber sessions, GRE
   tunneling will provide a means for the Foreign Agent and Home Agent
   to identify data streams for the individual sessions based on the GRE
   key.  In the absence of this key identifier, the data streams cannot
   be distinguished from each other -- a significant drawback when using
   IP-in-IP tunneling.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on
   Internet Standards is available in 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/rfc6245.

Yegani, et al.               Standards Track                    [Page 1]
RFC 6245                  GRE Key Ext. for MIP4                 May 2011

Copyright Notice

   Copyright (c) 2011 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
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   publication of this document.  Please review these documents
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1. Introduction ....................................................2
   2. Terminology .....................................................3
   3. GRE Key Extension ...............................................3
   4. Operation and Use of the GRE Key Extension ......................3
      4.1. Foreign Agent Requirements for GRE Tunneling Support .......3
      4.2. Home Agent Requirements for GRE Tunneling Support ..........4
      4.3. Mobile Node Requirements for GRE Tunneling Support .........5
   5. GRE Key Extension and Tunneling Procedures ......................5
   6. IANA Considerations .............................................6
   7. Security Considerations .........................................6
   8. Acknowledgements ................................................7
   9. Normative References ............................................7

1.  Introduction

   This document specifies a new extension for use by a Foreign Agent
   (FA) operating Mobile IP for IPv4.  The new extension allows a
   Foreign Agent to request Generic Routing Encapsulation (GRE)
   [RFC2784] tunneling without disturbing the Home Agent (HA) behavior
   specified for Mobile IPv4 [RFC5944].  This extension contains the GRE
   key [RFC2890] required for establishing a GRE tunnel between the FA
   and the HA.

   GRE tunneling with the Key field allows the operators to have home
   networks that consist of multiple Virtual Private Networks (VPNs),
   which may have overlapping home addresses.  When the tuple <Care of