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Versions: 00 01

Internet Draft                                         Lou Berger (LabN)
Category: Standards Track                     Russ White (Cisco Systems)
Expiration Date: August 25, 2008              Eric Rosen (Cisco Systems)

                                                       February 25, 2008

                BGP IPSec Tunnel Encapsulation Attribute


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Copyright Notice

   Copyright (C) The IETF Trust (2008).


   The BGP Encapsulation Subsequence Address Family Identifiers (SAFI)
   provides a method for the dynamic exchange of encapsulation
   information, and the indication of encapsulation protocol types to be
   used for different next hops.  Currently support for GRE and L2TPv3
   tunnel types are defined.  This document defines support for IPsec
   tunnel types.

Berger, et. al.              Standards Track                    [Page 1]

Internet-Draft    draft-berger-idr-encaps-ipsec-01.txt February 25, 2008


 1      Introduction  ..............................................   3
 1.1    Conventions used in this document  .........................   3
 2      IPsec Tunnel Encapsulation Types  ..........................   3
 3      Use of IPsec  ..............................................   4
 4      IPsec Tunnel Authenticator sub-TLV  ........................   4
 4.1    Use of the IPsec Tunnel Authenticator sub-TLV  .............   5
 5      Security Considerations  ...................................   5
 6      IANA Considerations  .......................................   6
 7      References  ................................................   6
 7.1    Normative References  ......................................   6
 7.2    Informative References  ....................................   7
 8      Acknowledgments  ...........................................   8
 9      Authors' Addresses  ........................................   8
10      Full Copyright Statement  ..................................   8
11      Intellectual Property  .....................................   9

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Internet-Draft    draft-berger-idr-encaps-ipsec-01.txt February 25, 2008

1. Introduction

   The BGP [RFC4271] Encapsulation Subsequence Address Family
   Identifiers (SAFI) allows for the communication of tunnel information
   and the association of this information to a BGP next hop.  The
   Encapsulation SAFI can be used to support the mapping of prefixes to
   next hops and tunnels of the same address family, IPv6 prefixes to
   IPv4 next hops and tunnels using [RFC4798], and IPv4 prefixes to IPv6
   next hops and tunnels using [V4NLRI-V6NH].  The Encapsulation SAFI
   can also be used to support the mapping of VPN prefixes to tunnels
   when VPN prefixes are advertised per [RFC4364] or [RFC4659].
   [SOFTWIRES] provides useful context for the use of the Encapsulation

   The Encapsulation SAFI is defined in [ENCAPS-SAFI].  [ENCAPS-SAFI]
   also defines support for the GRE [RFC2784] and L2TPv3 [RFC3931]
   tunnel types.  This document builds on [ENCAPS-SAFI] and defines
   support for IPsec tunnels.  Support is defined for IP Authentication
   Header in Tunnel-mode (AH), [RFC4302], and for IP Encapsulating
   Security Payload in Tunnel-mode (ESP), [RFC4303].  Support for IP-in-
   IP, [RFC2003], and MPLS-in-IP, [RFC4023] protected by IPsec Transport
   Mode is also defined.

   The Encapsulation NLRI Format is not modified by this document.

1.1. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

2. IPsec Tunnel Encapsulation Types

   Per [ENCAPS-SAFI], tunnel type is indicated in the Tunnel
   Encapsulation attribute. This document defines the following tunnel
   type values:

     - AH in Tunnel-mode: Tunnel Type = 3

     - ESP in Tunnel-mode: Tunnel Type = 4

     - IP-in-IP Tunnel with IPsec Transport Mode: Tunnel Type = 5

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     - MPLS-in-IP Tunnel with IPsec Transport Mode: Tunnel Type = 6

     Note, see Section 4.3 of [ENCAPS-SAFI] for a discussion on the
     advertisement and use of multiple tunnel types.

   This document does not specify the use of the sub-TLV types defined
   in [ENCAPS-SAFI] with these tunnel types.  See below for the
   definition of an IPsec tunnel type specific sub-TLV.

3. Use of IPsec

   If a R1 is a BGP speaker that receives an Encapsulation SAFI update
   from another BGP speaker, R2, then if R1 has any data packets for
   which R2 is the BGP next hop, R1 MUST initiate an IPsec SA of the
   specified "tunnel type", and all such data packets MUST be sent
   through that SA.

   Let R1 and R2 be two BGP speakers that may send data packets through
   R3, such that the data packets from R1 and from R2 may be received by
   R3 over the same interface.  Then if R3 has sent an update containing
   an Encapsulation SAFI, and if this update specifies an IPsec tunnel
   type, and if this update is received by R2, and an Encapsulation-SAFI
   with an IPsec tunnel type, MUST also be received by R1.  That is, on
   a given interface, if IPsec is required for any data packets, it MUST
   be required for all.  It does not necessarily need to be required for
   control packets that are directly addressed to R3.

   Security policy has the granularity of BGP speaker to BGP speaker.
   The required security policies must be configured into the BGP
   speakers, and the policy for each SA is negotiated via IKE.

4. IPsec Tunnel Authenticator sub-TLV

   This document defines a new sub-TLV for use with the Tunnel
   Encapsulation Attribute defined in [ENCAPS-SAFI].  The new sub-TLV is
   referred to as the "IPsec Tunnel Authenticator sub-TLV" and MAY be
   included in any Encapsulation SAFI NLRI ([ENCAPS-SAFI]) indicating a
   Tunnel Type defined in this document. Support for the IPsec Tunnel
   Authenticator sub-TLV" MUST be implemented whenever the tunnel types
   defined in this document are implemented.  However, its use is
   OPTIONAL, and is a matter of policy.

Berger, et. al.              Standards Track                    [Page 4]

Internet-Draft    draft-berger-idr-encaps-ipsec-01.txt February 25, 2008

   The sub-TLV type of the IPsec Tunnel Authenticator sub-TLV is 3.  The
   sub-TLV length is variable.  The structure of the sub-TLV is as

     - Authenticator Type: two octets

       This document defines authenticator type 1, "SHA-1 hash of public
       key", as defined in section 3.7 of RFC 4306.

     - Value: (variable)

       A value used to authenticate the BGP speaker that generated this
       NLRI.  The length of this field is is not encoded explicitly, but
       can be calculated as (sub-TLV length - 2).

       In the case of authenticator type 1, this field contains the
       20-octet value of the hash.

   A BGP speaker which sends the IPsec Tunnel Authenticator sub-TLV with
   authenticator type 1 MUST be configured with a certificate containing
   the public key whose hash is sent in the value field of the sub-TLV.
   This certificate MAY be self-signed.

4.1. Use of the IPsec Tunnel Authenticator sub-TLV

   If a IPsec Tunnel Authenticator sub-TLV with authenticator type 1 is
   present in the Encapsulation SAFI update, then R1 (as defined above
   in Section 3) must use IKE to obtain a certificate from R2 (as
   defined above in Section 3), and R2 must send a certificate
   containing the public key whose hash occurred in the value field of
   the IPsec Tunnel Authenticator sub-TLV.  R1 MUST NOT attempt to
   establish an SA to R2 UNLESS the public key in the certificate hashes
   to the same value that occurs in the IPsec Tunnel Authenticator sub-

5. Security Considerations

   This document uses IP based tunnel technologies to support data plane
   transport.  Consequently, the security considerations of those tunnel
   technologies apply.  This document defines support for IPsec AH
   [RFC4302] and ESP [RFC4303].  The security considerations from those
   documents apply to the data plane aspects of this document.

   As with [ENCAPS-SAFI], any modification of the information that is
   used to form encapsulation headers, or to choose a tunnel type, or to
   choose a particular tunnel for a particular payload type, user data

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Internet-Draft    draft-berger-idr-encaps-ipsec-01.txt February 25, 2008

   packets may end up getting misrouted, misdelivered, and/or dropped.
   Misdelivery is less of an issue when IPsec is used as such
   misdelivery is likely to result in a failure of authentication or
   decryption at the receiver.  Furthermore, in environments where
   authentication of BGP speakers is desired, the IPsec Tunnel
   Authenticator sub-TLV defined in Section 4 may be used.

   More broadly, the security considerations for the transport of IP
   reachability information using BGP are discussed in [RFC4271] and
   [RFC4272], and are equally applicable for the extensions described in
   this document.

6. IANA Considerations

   IANA is requested to administer assignment of new namespaces and new
   values for namespaces defined in this document and reviewed in this

   Upon approval of this document, the IANA will make the assignment in
   the Tunnel TLVs and sub-TLVs section of the registry.

      Tunnel Type                                      Reference
      -----------                                      ---------
      AH:                                      Type = 3 [This document]
      ESP:                                     Type = 4 [This document]
      IP-in-IP tunnel
          with IPsec Transport Mode:           Type = 5 [This document]
      MPLS-in-IP tunnel
          with IPsec Transport Mode:           Type = 6 [This document]

      Tunnel Type  Sub-TLV Type                         Reference
      -----------  ------------                         ---------
        3,4,5,6    IPsec Tunnel Authenticator: Type = 3 [This document]

7. References

7.1. Normative References

   [ENCAPS-SAFI] Mohapatra, P., Rosen, E., "BGP Information SAFI
                 and BGP Tunnel Encapsulation Attribute", Work in
                 Progress, draft-ietf-idr-encaps-safi-00.txt,
                 August 2007.

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   [RFC4271]   Rekhter, Y., Ed. et al, "A Border Gateway Protocol 4
               (BGP-4)", RFC 4271, January 2006.

7.2. Informative References

   [RFC2003]   Perkins, C., "IP Encapsulation within IP", RFC 2003,
               October 1996.

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

   [RFC2784]   Farinacci, D., et al, "Generic Routing Encapsulation
               (GRE)", RFC 2784, March 2000.

   [RFC3931]   Lau, J., Ed., et al, "Layer Two Tunneling Protocol -
               Version 3 (L2TPv3)", RFC 3931, March 2005.

   [RFC4023]   Worster, T., Rekhter, Y., Rosen, E., Ed.,
               "Encapsulating MPLS in IP or Generic Routing
               Encapsulation (GRE)", RFC 4023, March 2005.

   [RFC4272]   Murphy, S., "BGP Security Vulnerabilities Analysis",
               RFC 4272, January 2006.

   [RFC4302]   Kent, S., "IP Authentication Header", RFC 4302,
               December 2005.

   [RFC4303]   Kent, S., "IP Encapsulating Security Payload (ESP)"
               RFC 4303, December 2005.

   [RFC4364]   Rosen, E., Rekhter, Y., "BGP/MPLS IP Virtual Private
               Networks (VPNs)", RFC 4364, February 2006.

   [RFC4659]   De Clercq, J., et al, "BGP-MPLS IP Virtual Private
               Network (VPN) Extension for IPv6 VPN", RFC 4659,
               September 2006.

   [RFC4798]   J. De Clercq, D. Ooms, S. Prevost, F. Le Faucheur,
               "Connecting IPv6 Islands over IPv4 MPLS using IPv6
               Provider Edge Routers (6PE)", RFC 4798, February 2007.

   [SOFTWIRES] Wu, J. et al, "Softwire Mesh Framework", Work in
               Progress, draft-ietf-softwire-mesh-framework-03.txt,
               January 2008.

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   [V4NLRI-V6NH] F. Le Faucheur, E. Rosen, "Advertising an IPv4 NLRI
                 with an IPv6 Next Hop", Work in Progress,
                 draft-ietf-idr-v4nlri-v6nh-01.txt, October 2007.

8. Acknowledgments

   The authors wish to thank Sam Hartman and Tero Kivinen for their help
   with the security-related issues.  However, it should be noted that
   they have not reviewed this revision of the draft.

9. Authors' Addresses

   Lou Berger
   LabN Consulting, L.L.C.
   Phone: +1-301-468-9228
   Email: lberger@labn.net

   Russ White
   Cisco Systems
   Email: riw@cisco.com

   Eric C. Rosen
   Cisco Systems, Inc.
   1414 Massachusetts Avenue
   Boxborough, MA, 01719
   Email: erosen@cisco.com

10. Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
   retain all their rights.

   This document and the information contained herein are provided on an

Berger, et. al.              Standards Track                    [Page 8]

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11. Intellectual Property

   The IETF takes no position regarding the validity or scope of any
   Intellectual Property Rights or other rights that might be claimed
   to pertain to the implementation or use of the technology
   described in this document or the extent to which any license
   under such rights might or might not be available; nor does it
   represent that it has made any independent effort to identify any
   such rights.  Information on the procedures with respect to rights
   in RFC documents can be found in BCP 78 and BCP 79.

   Copies of IPR disclosures made to the IETF Secretariat and any
   assurances of licenses to be made available, or the result of an
   attempt made to obtain a general license or permission for the use
   of such proprietary rights by implementers or users of this
   specification can be obtained from the IETF on-line IPR repository
   at http://www.ietf.org/ipr.

   The IETF invites any interested party to bring to its attention
   any copyrights, patents or patent applications, or other
   proprietary rights that may cover technology that may be required
   to implement this standard.  Please address the information to the
   IETF at ietf-ipr@ietf.org.


   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).

Berger, et. al.              Standards Track                    [Page 9]

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