Host Identity Protocol (HIP) Rendezvous Extension
RFC 5204

Network Working Group                                        J. Laganier
Request for Comments: 5204                              DoCoMo Euro-Labs
Category: Experimental                                         L. Eggert
                                                                   Nokia
                                                              April 2008

           Host Identity Protocol (HIP) Rendezvous Extension

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Abstract

   This document defines a rendezvous extension for the Host Identity
   Protocol (HIP).  The rendezvous extension extends HIP and the HIP
   registration extension for initiating communication between HIP nodes
   via HIP rendezvous servers.  Rendezvous servers improve reachability
   and operation when HIP nodes are multi-homed or mobile.

Laganier & Eggert             Experimental                      [Page 1]
RFC 5204                HIP Rendezvous Extension              April 2008

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  3
   3.  Overview of Rendezvous Server Operation  . . . . . . . . . . .  4
     3.1.  Diagram Notation . . . . . . . . . . . . . . . . . . . . .  5
     3.2.  Rendezvous Client Registration . . . . . . . . . . . . . .  6
     3.3.  Relaying the Base Exchange . . . . . . . . . . . . . . . .  6
   4.  Rendezvous Server Extensions . . . . . . . . . . . . . . . . .  7
     4.1.  RENDEZVOUS Registration Type . . . . . . . . . . . . . . .  7
     4.2.  Parameter Formats and Processing . . . . . . . . . . . . .  8
       4.2.1.  RVS_HMAC Parameter . . . . . . . . . . . . . . . . . .  8
       4.2.2.  FROM Parameter . . . . . . . . . . . . . . . . . . . .  9
       4.2.3.  VIA_RVS Parameter  . . . . . . . . . . . . . . . . . . 10
     4.3.  Modified Packets Processing  . . . . . . . . . . . . . . . 10
       4.3.1.  Processing Outgoing I1 Packets . . . . . . . . . . . . 10
       4.3.2.  Processing Incoming I1 Packets . . . . . . . . . . . . 11
       4.3.3.  Processing Outgoing R1 Packets . . . . . . . . . . . . 11
       4.3.4.  Processing Incoming R1 Packets . . . . . . . . . . . . 11
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
   7.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 13
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 13
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 14

Laganier & Eggert             Experimental                      [Page 2]
RFC 5204                HIP Rendezvous Extension              April 2008

1.  Introduction

   The Host Identity Protocol (HIP) Architecture [RFC4423] introduces
   the rendezvous mechanism to help a HIP node to contact a frequently
   moving HIP node.  The rendezvous mechanism involves a third party,
   the rendezvous server (RVS), which serves as an initial contact point
   ("rendezvous point") for its clients.  The clients of an RVS are HIP
   nodes that use the HIP Registration Extension [RFC5203] to register
   their HIT->IP address mappings with the RVS.  After this
   registration, other HIP nodes can initiate a base exchange using the
   IP address of the RVS instead of the current IP address of the node
   they attempt to contact.  Essentially, the clients of an RVS become
   reachable at the RVS's IP address.  Peers can initiate a HIP base
   exchange with the IP address of the RVS, which will relay this
   initial communication such that the base exchange may successfully
   complete.

2.  Terminology

   This section defines terms used throughout the remainder of this
   specification.

   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].

   In addition to the terminology defined in the HIP specification
   [RFC5201] and the HIP Registration Extension [RFC5203], this document
   defines and uses the following terms:

   Rendezvous Service
      A HIP service provided by a rendezvous server to its rendezvous
      clients.  The rendezvous server offers to relay some of the
      arriving base exchange packets between the initiator and