Encrypted Signaling Transport Modes for the Host Identity Protocol
RFC 6261

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Internet Engineering Task Force (IETF)                        A. Keranen
Request for Comments: 6261                                      Ericsson
Category: Experimental                                          May 2011
ISSN: 2070-1721

                Encrypted Signaling Transport Modes for
                       the Host Identity Protocol

Abstract

   This document specifies two transport modes for Host Identity
   Protocol (HIP) signaling messages that allow them to be conveyed over
   encrypted connections initiated with the Host Identity Protocol.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for examination, experimental implementation, and
   evaluation.

   This document defines an Experimental Protocol for the Internet
   community.  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/rfc6261.

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
   (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.

Keranen                       Experimental                      [Page 1]
RFC 6261         HIP Encrypted Signaling Transport Modes        May 2011

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  2
   3.  Transport Mode Negotiation . . . . . . . . . . . . . . . . . .  3
     3.1.  Mode Negotiation in the HIP Base Exchange  . . . . . . . .  3
     3.2.  Mode Negotiation after the HIP Base Exchange . . . . . . .  5
     3.3.  Error Notifications  . . . . . . . . . . . . . . . . . . .  5
   4.  HIP Messages on Encrypted Connections  . . . . . . . . . . . .  5
     4.1.  ESP Mode . . . . . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  ESP-TCP Mode . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  Recovering from Failed Encrypted Connections . . . . . . . . .  7
   6.  Host Mobility and Multihoming  . . . . . . . . . . . . . . . .  8
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  9
   9.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     10.1. Normative References . . . . . . . . . . . . . . . . . . .  9
     10.2. Informational References . . . . . . . . . . . . . . . . . 10
   Appendix A.  Mobility and Multihoming Examples . . . . . . . . . . 11

1.  Introduction

   Host Identity Protocol (HIP) [RFC5201] signaling messages can be
   exchanged over plain IP using the protocol number reserved for this
   purpose, or over UDP using the UDP port reserved for HIP NAT
   traversal [RFC5770].  When two hosts perform a HIP base exchange,
   they set up an encrypted connection between them for data traffic,
   but continue to use plain IP or UDP for HIP signaling messages.

   This document defines how the encrypted connection can be used also
   for HIP signaling messages.  Two different modes are defined: HIP
   over Encapsulating Security Payload (ESP) and HIP over TCP.  The
   benefit of sending HIP messages over ESP is that all signaling
   traffic (including HIP headers) will be encrypted.  If HIP messages
   are sent over TCP (which in turn is transported over ESP), TCP can
   handle also message fragmentation where needed.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Keranen                       Experimental                      [Page 2]
RFC 6261         HIP Encrypted Signaling Transport Modes        May 2011

3.  Transport Mode Negotiation

   This section defines how support for different HIP signaling message
   transport modes is indicated and how the use of different modes is