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HIP Working Group                                           G. Camarillo
Internet-Draft                                                A. Keranen
Intended status: Experimental                                   Ericsson
Expires: January 7, 2010                                    July 6, 2009


        Host Identity Protocol (HIP) Multi-hop Routing Extension
                     draft-camarillo-hip-via-00.txt

Status of this Memo

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Copyright Notice

   Copyright (c) 2009 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
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   Please review these documents carefully, as they describe your rights
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Abstract

   This document specifies two extensions to HIP to implement multi-hop
   routing.  The first extension allows a HIP packet to carry the list
   of hosts that forwarded it.  The second extension allows implementing



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   source routing in HIP.  That is, a host sending a HIP packet can
   define a set of hosts that the HIP packet should traverse.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     2.1.  Requirements Language . . . . . . . . . . . . . . . . . . . 3
     2.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Overview of Operations  . . . . . . . . . . . . . . . . . . . . 3
   4.  Protocol Definitions  . . . . . . . . . . . . . . . . . . . . . 3
     4.1.  Creating and Processing Via Route Lists . . . . . . . . . . 4
     4.2.  Creating Destination Route Lists  . . . . . . . . . . . . . 4
     4.3.  Processing Destination Route Lists  . . . . . . . . . . . . 4
   5.  Packet Formats  . . . . . . . . . . . . . . . . . . . . . . . . 5
     5.1.  Source and Destination Route List Parameters  . . . . . . . 6
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 7
     7.1.  Forwarding Loops  . . . . . . . . . . . . . . . . . . . . . 7
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 7
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 7
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 8



























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1.  Introduction

   When HIP [RFC5201] is used in certain contexts (e.g., in a HIP BONE
   [I-D.ietf-hip-bone] overlay), hosts need the ability to perform
   source routing.  That is, a host needs the ability to send a HIP
   packet that will traverse a set of hosts before reaching its
   destination.  This document defines an extension that provides HIP
   with this functionality.

   Additionally, when HIP packets are routed through multiple hosts,
   some of these hosts (e.g., the destination host) need the ability to
   know the hosts a particular packet traversed.  This document defines
   another extension that provides HIP with this functionality.

   These two extensions enable multi-hop routing in HIP.  Before these
   extensions were specified, HIP only supported a single intermediate
   host (i.e., a rendezvous server [RFC5204]) between the source of a
   HIP packet and its destination.


2.  Terminology

2.1.  Requirements Language

   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].

2.2.  Definitions

   Route list:  A list of HITs of the hosts that a HIP packet has
      traversed or should traverse.

   Symmetric routing:  A response to a message is routed back using the
      same set of intermediary nodes as the original message used,
      except in reversed order.


3.  Overview of Operations

   TODO: this will be a non-normative section that will give a high-
   level overview about how these extensions work.


4.  Protocol Definitions






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4.1.  Creating and Processing Via Route Lists

   When a host sending a HIP packet needs to record the hosts that are
   on the path that the HIP packet traverses, it includes an empty
   ROUTE_VIA parameter to the packet.

   A host that receives a packet with a ROUTE_VIA parameter adds its own
   HIT to the end of the ROUTE_VIA parameter, unless it is the receiver
   of the packet.  If the host uses a different HIT on the HIP
   association it used for receiving the packet than for sending it
   forward, it should also add the receiving HIT to the route list
   before the sending HIT.

   If the host is the receiver of the packet, and the received packet
   generates a response HIP packet, the host checks the SYMMETRIC flag
   from the ROUTE_VIA parameter.  If the SYMMETRIC flag is set, the host
   MUST create a ROUTE_DST parameter from the ROUTE_VIA parameter as
   described in Section 4.2 and include it in the response packet.
   Also, if an intermediary host generates a new HIP packet (e.g, an
   error NOTIFY packet) due to a HIP packet that had a ROUTE_VIA
   parameter with SYMMETRIC flag set, and the new packet is intended for
   the sender of the original HIP packet, the host MUST construct and
   add a ROUTE_DST parameter into the new packet as in the previous
   case.

4.2.  Creating Destination Route Lists

   A host can add a ROUTE_DST parameter to a new HIP packet when it
   needs to define the hosts that should be on the path the HIP packet
   traverses.  The host may either decide the path independently, or it
   may create the path based on a ROUTE_VIA parameter.  Only the
   originator of a signed HIP packet can add a ROUTE_DST parameter to
   the HIP packet since the parameter is covered by the signature.

   When a host creates a ROUTE_DST parameter due to receiving a packet
   with a ROUTE_VIA parameter, it copies all the HITs in the ROUTE_VIA
   parameter to the ROUTE_DST parameter, but in reversed order.  This
   results in HIP response packet being forwarded using the same set of
   hosts as the packet for which the response was generated for.

4.3.  Processing Destination Route Lists

   When a host receives a HIP packet that contains a ROUTE_DST
   parameter, it first looks up its own HIT from the route list.  If
   host's own HIT is not in the list and the host is not the receiver of
   the packet, the packet was incorrectly forwarded and MUST be dropped.
   Next hop for the packet is the HIT after host's own HIT in the list.
   If the host's HIT was the last HIT in the list, the next hop is the



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   receiver's HIT in the HIP header.


5.  Packet Formats

   This memo defines two new HIP parameters that are used for recording
   a route via multiple hosts (ROUTE_VIA) and to define a route a packet
   should traverse by the sender of the packet (ROUTE_DST).

   The ROUTE_DST parameter is integrity protected with the signature
   (where present) but ROUTE_VIA is not so that intermediary hosts can
   add their own HITs to the list.  Both parameters have critical type
   (as defined in Section 5.2.1 of [RFC5201]) since the packet will not
   be properly routed unless all hosts on path recognize the parameters.





































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5.1.  Source and Destination Route List Parameters

      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
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Type              |             Length            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |             Flags             |            Reserved           |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                            HIT #1                             |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     .                               .                               .
     .                               .                               .
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |                                                               |
     |                            HIT #n                             |
     |                                                               |
     |                                                               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


     Type      [ TBD by IANA
               ROUTE_DST: 971
               ROUTE_VIA: 65525 ]
     Length    length in octets, excluding Type and Length
               (i.e., number-of-HITs * 16 + 4)
     Flags     bit flags that can be used for requesting special
               handling of the parameter
     Reserved  reserved for future use
     HIT       Host Identity Tag of one of the hosts on the path

        Figure 1: Format of the ROUTE_VIA and ROUTE_DST parameters

   Figure 1 shows the format of both ROUTE_VIA and ROUTE_DST parameters.
   The ROUTE_DST parameter, if present, MUST have at least one HIT, but
   the ROUTE_VIA parameter can also have zero HITs.  Both can contain at
   most 32 HITs.  The Flags field is used for requesting special
   handling for certain Route lists.  The flags defined in this document
   are shown in Table 1.  The Reserved field can be used by future
   extensions; it MUST be zero when sending and ignored when receiving
   this parameter.







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   +-----+-----------+-------------------------------------------------+
   | Pos | Name      | Purpose                                         |
   +-----+-----------+-------------------------------------------------+
   |  0  | SYMMETRIC | The response packet MUST be sent using          |
   |     |           | ROUTE_DST list made from this ROUTE_VIA list,   |
   |     |           | i.e., using symmetric routing.                  |
   +-----+-----------+-------------------------------------------------+

                 Table 1: Bit flags in ROUTE_VIA parameter

   The "Pos" column in Table 1 shows the bit position of the flag (as in
   Figure 1) in the Flags field, "Name" gives the name of the flag used
   in this document, and "Purpose" gives brief description of the
   meaning of that flag.


6.  IANA Considerations

   This section is to be interpreted according to [RFC5226].

   This document updates the IANA Registry for HIP Parameter Types
   [RFC5201] by assigning new HIP Parameter Type values for the new HIP
   Parameters: ROUTE_VIA and ROUTE_DST (defined in Section 5).


7.  Security Considerations

7.1.  Forwarding Loops

   A malicious host could craft a destination route list that contains
   the same HIT more than once and thus create a forwarding loop.  Since
   the IP layer TTL is decremented on each hop, the loop will be
   eventually broken, but hosts may additionally protect themselves
   against this attack by checking that their own HIT is in the
   destination list only once and drop invalid packets.


8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5201]  Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson,
              "Host Identity Protocol", RFC 5201, April 2008.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an



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              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

8.2.  Informative References

   [RFC5204]  Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
              Rendezvous Extension", RFC 5204, April 2008.

   [I-D.ietf-hip-bone]
              Camarillo, G., Nikander, P., Hautakorpi, J., and A.
              Johnston, "HIP BONE: Host Identity Protocol (HIP) Based
              Overlay Networking  Environment", draft-ietf-hip-bone-01
              (work in progress), March 2009.


Authors' Addresses

   Gonzalo Camarillo
   Ericsson
   Hirsalantie 11
   02420 Jorvas
   Finland

   Email: Gonzalo.Camarillo@ericsson.com


   Ari Keranen
   Ericsson
   Hirsalantie 11
   02420 Jorvas
   Finland

   Email: ari.keranen@ericsson.com


















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