



OSPF Working Group                                            X. Xu, Ed.
Internet-Draft                                                    Huawei
Intended status: Standards Track                        B. Decraene, Ed.
Expires: April 12, 2018                                           Orange
                                                               R. Raszuk
                                                            Bloomberg LP
                                                            L. Contreras
                                                          Telefonica I+D
                                                                L. Jalil
                                                                 Verizon
                                                         October 9, 2017


           The Tunnel Encapsulations OSPF Router Information
                  draft-ietf-ospf-encapsulation-cap-09

Abstract

   Networks use tunnels for a variety of reasons.  A large variety of
   tunnel types are defined and the tunnel encapsulator router needs to
   select a type of tunnel which is supported by the tunnel decapsulator
   router.  This document defines how to advertise, in OSPF Router
   Information Link State Advertisement (LSAs), the list of tunnel
   encapsulations supported by the tunnel decapsulator.

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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 12, 2018.




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Copyright Notice

   Copyright (c) 2017 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
   (https://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
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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Tunnel Encapsulations TLV . . . . . . . . . . . . . . . . . .   3
   4.  Tunnel Sub-TLV  . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  Tunnel Parameter Sub-TLVs . . . . . . . . . . . . . . . . . .   4
     5.1.  Encapsulation Sub-TLV . . . . . . . . . . . . . . . . . .   5
     5.2.  Protocol Type Sub-TLV . . . . . . . . . . . . . . . . . .   5
     5.3.  Endpoint Sub-TLV  . . . . . . . . . . . . . . . . . . . .   5
     5.4.  Color Sub-TLV . . . . . . . . . . . . . . . . . . . . . .   6
     5.5.  Load-Balancing Block Sub-TLV  . . . . . . . . . . . . . .   6
     5.6.  IP QoS Field  . . . . . . . . . . . . . . . . . . . . . .   6
     5.7.  UDP Destination Port  . . . . . . . . . . . . . . . . . .   7
   6.  Operation . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
     7.1.  OSPF Router Information . . . . . . . . . . . . . . . . .   7
     7.2.  Tunnel Parameter Sub-TLVs Registry  . . . . . . . . . . .   7
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     11.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     11.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Introduction

   Networks use tunnels for a variety of reasons, such as:

   o  Partial deployment of IPv6 in IPv4 networks or IPv4 in IPv6
      networks as described in [RFC5565], where IPvx tunnels are used
      between IPvx-enabled routers so as to traverse non-IPvx routers.



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   o  Remote Loop-Free Alternate (RLFA) repair tunnels as described in
      [RFC7490], where tunnels are used between the Point of Local
      Repair and the selected PQ node.

   The tunnel encapsulator router needs to select a type of tunnel which
   is supported by the tunnel decapsulator router.  This document
   defines how to advertise, in OSPF Router Information Link State
   Advertisement (LSAs), the list of tunnel encapsulations supported by
   the tunnel decapsulator.  In this document, OSPF refers to both
   OSPFv2 [RFC2328] and OSPFv3 [RFC5340].

2.  Terminology

   This memo makes use of the terms defined in [RFC7770].

3.  Tunnel Encapsulations TLV

   Routers advertise their supported tunnel encapsulation type(s) by
   advertising a new TLV of the OSPF Router Information (RI) Opaque LSA
   [RFC7770], referred to as the Tunnel Encapsulations TLV.  This TLV is
   applicable to both OSPFv2 and OSPFv3.

   The Type code of the Tunnel Encapsulations is TBD1, the Length value
   is variable, and the Value field contains one or more Tunnel Sub-TLVs
   as defined in Section 4.  Each Tunnel Sub-TLV indicates a particular
   encapsulation format that the advertising router supports along with
   the parameters corresponding to the tunnel type.

   The Tunnel Encapsulations TLV MAY appear more than once within a
   given OSPF Router Information (RI) Opaque LSA.  If the Tunnel
   Encapsulations TLV appears more than once in an OSPF Router
   Information LSA, the set of all Tunnel Sub-TLVs from all Tunnel
   Encapsulations TLV SHOULD be considered.  The scope of the
   advertisement depends on the application but it is recommended that
   it SHOULD be domain-wide.

4.  Tunnel Sub-TLV

   The Tunnel Sub-TLV is structured as follows:












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       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |    Tunnel Type (2 Octets)     |        Length (2 Octets)      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      |               Tunnel Parameter Sub-TLVs                      |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                         Figure 1: Tunnel Sub-TLV

      Tunnel Type (2 octets): Identifies the type of tunneling
      technology signaled.  Tunnel types are shared with the BGP
      extension [I-D.ietf-idr-tunnel-encaps] and hence are defined in
      the IANA registry "BGP Tunnel Encapsulation Attribute Tunnel
      Types".  Unknown Tunnel types are to be ignored upon receipt.

      Length (2 octets): Unsigned 16-bit integer indicating the total
      number of octets of the value field.

      Value (variable): Zero or more Tunnel Parameter Sub-TLVs as
      defined in Section 5.

   If a Tunnel Sub-TLV is invalid, it MUST be ignored and skipped.
   However, other Tunnel Sub-TLVs MUST be considered

5.  Tunnel Parameter Sub-TLVs

   A Tunnel Parameter Sub-TLV is structured as follows:

              +---------------------------------------------+
              |   Tunnel Parameter Sub-Type   (2 Octets)    |
              +---------------------------------------------+
              |   Tunnel Parameter Length (2 Octets)        |
              +---------------------------------------------+
              |   Tunnel Parameter Value  (Variable)        |
              |                                             |
              +---------------------------------------------+

                    Figure 2: Tunnel Parameter Sub-TLV

      Tunnel Parameter Sub-Type (2 octets): Each sub-type defines a
      parameter of the Tunnel Sub-TLV.  Sub-Types are registered in the
      IANA registry "OSPF Tunnel Parameter Sub-TLVs" Section 7.2.






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      Tunnel Parameter Length (2 octets): Unsigned 16-bit integer
      indicating the total number of octets of the Tunnel Parameter
      Value field.

      Tunnel Parameter Value (variable): Encodings of the value field
      depend on the Sub-TLV type as enumerated above.  The following
      sub-sections define the encoding in detail.

   Any unknown Tunnel Parameter Sub-Type MUST be ignored and skipped
   upon receipt.  When a reserved value (See Section 7.2) is seen in an
   LSA, it MUST be treated as an invalid Tunnel Parameter Sub-TLV.  When
   a Tunnel Parameter Value has an incorrect syntax or semantic, it MUST
   be treated as an invalid Tunnel Parameter Sub-TLV.  If a Tunnel
   Parameter Sub-TLV is invalid, its Tunnel Sub-TLV MUST be ignored.
   However, other Tunnel Sub-TLVs MUST be considered.

5.1.  Encapsulation Sub-TLV

   This Sub-TLV type is 1.  The syntax, semantic, and usage of its value
   field are defined in Section 3.2 "Encapsulation Sub-TLVs for
   Particular Tunnel Types" of [I-D.ietf-idr-tunnel-encaps].

5.2.  Protocol Type Sub-TLV

   This Sub-TLV type is 2.  The syntax, semantic, and usage of its value
   field are defined in Section 3.4.1 "Protocol Type sub-TLV" of
   [I-D.ietf-idr-tunnel-encaps].

5.3.  Endpoint Sub-TLV

   This Sub-TLV type is 3.  It MUST be present once and only once in a
   given Tunnel Sub-TLV.  The value field contain two sub-fields:

      a two-octet Address Family sub-field

      an Address sub-field, whose length depends upon the Address
      Family.

        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
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |      Address Family           |           Address             ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                               +
       ~                     (Variable length)                         ~
       |                                                               |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                        Figure 3: Endpoint Sub-TLV



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   The Address Family subfield contains a value from IANA's "Address
   Family Numbers" registry.  In this document, we assume that the
   Address Family is either IPv4 or IPv6; use of other address families
   is outside the scope of this document.

   If the Address Family subfield contains the value for IPv4, the
   address subfield MUST contain an IPv4 address (a /32 IPv4 prefix).
   In this case, the length field of Remote Endpoint sub-TLV MUST
   contain the value 6.

   If the Address Family subfield contains the value for IPv6, the
   address sub-field MUST contain an IPv6 address (a /128 IPv6 prefix).
   In this case, the length field of Remote Endpoint sub-TLV MUST
   contain the value 18 (0x12).  IPv6 link local addresses are not valid
   values of the IP address field.

5.4.  Color Sub-TLV

   This Sub-TLV type is 4.  It may appear zero or more time in a given
   Tunnel Sub-TLV.  The value field is a 4-octet opaque unsigned
   integer.

   The color value is user-defined and configured locally on the
   advertising routers.  It may be used by service providers to define
   policies on the tunnel encapsulator routers, for example, to control
   the selection of the tunnel to use.

   This color value can be referenced by BGP routes carrying Color
   Extended Community [I-D.ietf-idr-tunnel-encaps].  If the tunnel is
   used to reach the BGP Next-Hop of BGP routes, then attaching a Color
   Extended Community to those routes express the willingness of the BGP
   speaker to use a tunnel of the same color.

5.5.  Load-Balancing Block Sub-TLV

   This Sub-TLV type is 5.  The syntax, semantic, and usage of its value
   field are defined in [RFC5640].

5.6.  IP QoS Field

   This Sub-TLV type is 6.  The syntax, semantic, and usage of its value
   field are defined in Section 3.3.1 "IPv4 DS Field" of
   [I-D.ietf-idr-tunnel-encaps].








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5.7.  UDP Destination Port

   This Sub-TLV type is 7.  The syntax, semantic, and usage of its value
   field are defined in Section 3.3.2 "UDP Destination Port" of
   [I-D.ietf-idr-tunnel-encaps].

6.  Operation

   The advertisement of a Tunnel Encapsulations Sub-TLV indicates that
   the advertising router supports a particular tunnel decapsulation
   along with the parameters to be used for the tunnel.  The decision to
   use that tunnel is driven by the capability of the tunnel
   encapsulator router to support the encapsulation type and the policy
   on the tunnel encapsulator router.  The Color Sub-TLV (See
   Section 5.4) may be used as an input to this policy.  Note that some
   tunnel types may require the execution of an explicit tunnel setup
   protocol before they can be used to transit data.

   A tunnel MUST NOT be used if there is no route toward the IP address
   specified in the Endpoint Sub-TLV (See Section 5.3) or if the route
   is not advertised in the same OSPF domain.

7.  IANA Considerations

7.1.  OSPF Router Information

   This document requests IANA to allocate a new code point from the
   OSPF Router Information (RI) registry.

       Value   TLV Name                    Reference
       -----   ----------------------      -------------
       TBD1    Tunnel Encapsulations       This document

             Figure 4: Tunnel Encapsulation Router Information

7.2.  Tunnel Parameter Sub-TLVs Registry

   This document requests IANA to create, under "Open Shortest Path
   First (OSPF) Parameters", a new registry "OSPF Tunnel Parameter Sub-
   TLVs" with the following registration procedure:

      The values in the range 1-34999 are to be allocated using the
      "Standards Action" registration procedure as defined in [RFC8126].

      The values in the range 35000-65499 are to be allocated using the
      "First Come, First Served" registration procedure.





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     Registry Name: OSPF Tunnel Parameter Sub-TLVs

   Value          Name                   Reference
   -----------    --------------------   ------------------------------
             0    Reserved               This document
             1    Encapsulation          This document
                                         & [I-D.ietf-idr-tunnel-encaps]
             2    Protocol Type          This document
                                         & [I-D.ietf-idr-tunnel-encaps]
             3    Endpoint               This document
             4    Color                  This document
             5    Load-Balancing Block   This document & [RFC5640]
             6    IP QoS                 This document
                                         & [I-D.ietf-idr-tunnel-encaps]
             7    UDP Destination Port   This document
                                         & [I-D.ietf-idr-tunnel-encaps]
       8-65499    Unassigned
   65500-65534    Experimental           This document
         65535    Reserved               This document

             Figure 5: OSPF Tunnel Parameter Sub-TLVs Registry

8.  Security Considerations

   Security considerations applicable to softwires can be found in the
   mesh framework [RFC5565].  In general, security issues of the tunnel
   protocols signaled through this OSPF capability extension are
   inherited.

   If a third-party is able to modify any of the information that is
   used to form encapsulation headers, to choose a tunnel type, or to
   choose a particular tunnel for a particular payload type, user data
   packets may end up getting misrouted, mis-delivered, and/or dropped.
   However, since an OSPF routing domain is usually a well-controlled
   network under a single administrative domain, the possibility of the
   above attack is very low.

   We note that the last paragraph of Section 6 forbid the establishment
   of a tunnel toward arbitrary destinations.  It prohibits a
   destination outside of the OSPF domain.  This avoid that a third-
   party gaining access to an OSPF router be able to send the traffic to
   other destinations, e.g., for inspection purposes.

   Security considerations for the base OSPF protocol are covered in
   [RFC2328] and [RFC5340].






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9.  Contributors

   Uma Chunduri
   Huawei
   Email: uma.chunduri@gmail.com

10.  Acknowledgements

   This document is partially inspired by [RFC5512].

   The authors would like to thank Greg Mirsky, John E Drake, Carlos
   Pignataro and Karsten Thomann for their valuable comments on this
   document.  Special thanks should be given to Acee Lindem for his
   multiple detailed reviews of this document and help.  The authors
   would like to thank Pete Resnick, Joe Touch, David Mandelberg,
   Sabrina Tanamal, Tim Wicinski, Amanda Baber for their Last Call
   reviews and thank Spencer Dawkins, Mirja Kuehlewind, Ben Campbell,
   Benoit Claise, Alvaro Retana, Adam Roach and Suresh Krishnan for
   their AD reviews.

11.  References

11.1.  Normative References

   [I-D.ietf-idr-tunnel-encaps]
              Rosen, E., Patel, K., and G. Velde, "The BGP Tunnel
              Encapsulation Attribute", draft-ietf-idr-tunnel-encaps-07
              (work in progress), July 2017.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5640]  Filsfils, C., Mohapatra, P., and C. Pignataro, "Load-
              Balancing for Mesh Softwires", RFC 5640,
              DOI 10.17487/RFC5640, August 2009,
              <https://www.rfc-editor.org/info/rfc5640>.

   [RFC7770]  Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and
              S. Shaffer, "Extensions to OSPF for Advertising Optional
              Router Capabilities", RFC 7770, DOI 10.17487/RFC7770,
              February 2016, <https://www.rfc-editor.org/info/rfc7770>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.



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11.2.  Informative References

   [RFC2328]  Moy, J., "OSPF Version 2", STD 54, RFC 2328,
              DOI 10.17487/RFC2328, April 1998,
              <https://www.rfc-editor.org/info/rfc2328>.

   [RFC5340]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
              for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
              <https://www.rfc-editor.org/info/rfc5340>.

   [RFC5512]  Mohapatra, P. and E. Rosen, "The BGP Encapsulation
              Subsequent Address Family Identifier (SAFI) and the BGP
              Tunnel Encapsulation Attribute", RFC 5512,
              DOI 10.17487/RFC5512, April 2009,
              <https://www.rfc-editor.org/info/rfc5512>.

   [RFC5565]  Wu, J., Cui, Y., Metz, C., and E. Rosen, "Softwire Mesh
              Framework", RFC 5565, DOI 10.17487/RFC5565, June 2009,
              <https://www.rfc-editor.org/info/rfc5565>.

   [RFC7490]  Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N.
              So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)",
              RFC 7490, DOI 10.17487/RFC7490, April 2015,
              <https://www.rfc-editor.org/info/rfc7490>.

Authors' Addresses

   Xiaohu Xu (editor)
   Huawei

   Email: xuxiaohu@huawei.com


   Bruno Decraene  (editor)
   Orange

   Email: bruno.decraene@orange.com


   Robert Raszuk
   Bloomberg LP

   Email: robert@raszuk.net








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   Luis M. Contreras
   Telefonica I+D

   Email: luismiguel.contrerasmurillo@telefonica.com


   Luay Jalil
   Verizon

   Email: luay.jalil@verizon.com









































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