Network Working Group                                            J. Dong
Internet-Draft                                                     Z. Li
Intended status: Standards Track                     Huawei Technologies
Expires: 12 January 2023                                          C. Xie
                                                                   C. Ma
                                                           China Telecom
                                                               G. Mishra
                                                            Verizon Inc.
                                                            11 July 2022


 Carrying Virtual Transport Network (VTN) Information in IPv6 Extension
                                 Header
                 draft-ietf-6man-enhanced-vpn-vtn-id-01

Abstract

   Virtual Private Networks (VPNs) provide different customers with
   logically separated connectivity over a common network
   infrastructure.  With the introduction and evolvement of 5G and other
   network scenarios, some existing or new customers may require
   connectivity services with advanced characteristics comparing to
   traditional VPNs.  Such kind of network service is called enhanced
   VPNs (VPN+).  VPN+ can be used to deliver IETF network slices, and
   could also be used for other application scenarios.

   A Virtual Transport Network (VTN) is a virtual underlay network which
   consists of a set of dedicated or shared network resources allocated
   from the physical underlay network, and is associated with a
   customized logical network topology.  VPN+ services can be delivered
   by mapping one or a group of overlay VPNs to the appropriate VTNs as
   the virtual underlay.  In packet forwarding, some fields in the data
   packet needs to be used to identify the VTN the packet belongs to, so
   that the VTN-specific processing can be performed on each node the
   packet traverses.

   This document proposes a new Hop-by-Hop option of IPv6 extension
   header to carry the VTN related information, which could used to
   identify the set of network resources allocated to a VTN and the
   rules for packet processing.  The procedure for processing the VTN
   option is also specified.

Status of This Memo

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





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   Copyright (c) 2022 IETF Trust and the persons identified as the
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  New IPv6 Extension Header Option for VTN  . . . . . . . . . .   4
   3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Adding VTN Option to Packet . . . . . . . . . . . . . . .   6
     3.2.  VTN based Packet Forwarding . . . . . . . . . . . . . . .   6
   4.  Operational Considerations  . . . . . . . . . . . . . . . . .   7
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     9.2.  Informative References  . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10








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1.  Introduction

   Virtual Private Networks (VPNs) provide different customers with
   logically isolated connectivity over a common network infrastructure.
   With the introduction and evolvement of 5G and other network
   scenarios, some existing or new customers may require connectivity
   services with advanced characteristics comparing to traditional VPNs,
   such as resource isolation from other services or guaranteed
   performance.  Such kind of network service is called enhanced VPN
   (VPN+).  VPN+ service requires the coordination and integration
   between the overlay VPNs and the capability and resources of the
   underlay network.  VPN+ can be used to deliver IETF network slices
   [I-D.ietf-teas-ietf-network-slices].

   [I-D.ietf-teas-enhanced-vpn] describes a framework and the candidate
   component technologies for providing VPN+ services.  It also
   introduces the concept of Virtual Transport Network (VTN).  A VTN is
   a virtual underlay network which consists of a set of dedicated or
   shared network resources allocated from the physical underlay
   network, and is associated with a logical network topology.  VPN+
   services can be delivered by mapping one or a group of overlay VPNs
   to the appropriate VTNs as the underlay, so as to provide the network
   characteristics required by the customers.  In packet forwarding,
   traffic of different VPN+ services needs to be processed separately
   based on the network resources and the logical topology associated
   with the corresponding VTN.  In the context of network slicing, VTN
   and NRP are considered as similar concepts, and NRP can be seen as an
   instantiation of VTN.

   [I-D.dong-teas-nrp-scalability] describes the scalability
   considerations and the possible optimizations for providing a
   relatively large number of VTNs for VPN+ services.  One approach to
   improve the data plane scalability of VTN is to introduce a dedicated
   VTN Resource Identifier (VTN Resource ID) in the data packet to
   identify the set of network resources allocated to a VTN, so that
   VTN-specific packet processing can be performed using that set of
   resources, which avoids the possible resource competition with
   services in other VTNs.  This is called Resource Independent (RI)
   VTN.  A VTN Resource ID represents a subset of the resources (e.g.
   bandwidth, buffer and queuing resources) allocated on a given set of
   links and nodes which constitute a logical network topology.  The
   logical topology associated with a VTN could be defined using
   mechanisms such as Multi-Topology [RFC4915], [RFC5120] or Flex-Algo
   [I-D.ietf-lsr-flex-algo], etc.

   This document proposes a mechanism to carry the VTN resource ID
   together with other VTN related information in a new Hop-by-Hop
   option called "VTN option" of IPv6 extension header [RFC8200] of IPv6



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   packet, so that on each network node along the packet forwarding
   path, the VTN option in the packet is parsed, and the obtained VTN
   Resource ID is used to instruct the network node to use the set of
   network resources allocated to the corresponding VTN to process and
   forward the packet.  The procedure for processing the VTN option is
   also specified.  This provides a scalable solution to support a
   relatively large number of VTNs in an IPv6 network.

1.1.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP14 RFC 2119 [RFC2119] RFC 8174 [RFC8174] when, and only when, they
   appear in all capitals, as shown here.

2.  New IPv6 Extension Header Option for VTN

   A new Hop-by-Hop option type "VTN" is defined to carry the VTN
   resource identifier and other VTN related information in an IPv6
   packet.  Its format is shown as below:

                          Option   Option
                           Type   Data Len
                        +--------+--------+
                        |BBCTTTTT| Length |
                        +--------+--------+--------+--------+
                Option  |  Flags |        Reserved          |
                 Data   +--------+--------+--------+--------+
                        |           VTN Resource ID         |
                        +--------+--------+--------+--------+
                     Figure 1. The format of VTN Option

   Option Type: 8-bit identifier of the type of option.  The type of VTN
   option is to be assigned by IANA.  The bits of the type field are
   defined as below:

   *  BB 00 The highest-order 2 bits are set to 00 to indicate that a
      node which does not recognize this type will skip over it and
      continue processing the header.

   *  C 0 The third highest-order bit is set to 0 to indicate this
      option does not change en route.

   *  TTTTT To be assigned by IANA.






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   Opt Data Len: 8-bit unsigned integer indicates the length of the
   option Data field of this option, in octets.  The value of Opt Data
   Len of VTN option SHOULD be set to 8.

   Flags: 8-bit flags field.  The most significant bit is defined in
   this document.

                                   0 1 2 3 4 5 6 7
                                  +-+-+-+-+-+-+-+-+
                                  |S|U U U U U U U|
                                  +-+-+-+-+-+-+-+-+

   *  S (Strict Match): The S flag is used to indicate whether the VTN
      Resource ID MUST be strictly matched for the processing of the
      packet.  When S flag is set to 1, if the VTN resource ID in the
      VTN option does not match with any of the VTN resource ID
      provisioned on the outgoing interface of the network node, the
      packet MUST be dropped.  When S flag is set to 0, if the VTN
      resource ID in the VTN option does not match with any of the VTN
      resource ID provisioned on the outgoing interface of the network
      node, the packet SHOULD be forwarded using the default set of
      network resource on the outgoing interface.

   *  U (Unused): These flags are reserved for future use.  They SHOULD
      be set to 0 on transmission and MUST be ignored on receipt.

   Reserved: 3-octet field reserved for future use.  SHOULD be set to 0
   on transmission and MUST be ignored on receipt.

   VTN Resource ID: 4-octet identifier which uniquely identifies the set
   of network resources allocated to a VTN.

   Note that, if a deployment found it useful, the four-octet VTN
   Resource ID field may be derived from the four-octet Single Network
   Slice Selection Assistance Information (S-NSSAI) defined in 3GPP
   [TS23501].

3.  Procedures

   As the VTN option needs to be processed by each node along the path
   for VTN-specific forwarding, it MUST be carried in IPv6 Hop-by-Hop
   options header.









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3.1.  Adding VTN Option to Packet

   When an ingress node of an IPv6 domain receives a packet, according
   to the traffic classification or mapping policy, the packet is
   steered into one of the VTNs in the network, then the packet MUST be
   encapsulated in an outer IPv6 header, and the Resource ID of the VTN
   which the packet is mapped to MUST be carried in the VTN option of
   the Hop-by-Hop Options header associated with the outer IPv6 header.

3.2.  VTN based Packet Forwarding

   On receipt of a packet with the VTN option, each network node which
   can process the VTN option in fast path MUST use the VTN Resource ID
   to determine the set of local network resources allocated to the VTN
   for packet processing.  The packet forwarding behavior is based on
   both the destination IP address and the VTN Resource ID.  More
   specifically, the destination IP address is used to determine the
   next-hop and the outgoing interface, and VTN Resource ID is used to
   determine the set of network resources on the outgoing interface
   which are allocated to the VTN for processing and sending the packet.
   If the VTN Resource ID does not match with any of the VTN Resource ID
   provisioned on the outgoing interface, the S flag in the VTN option
   is used to determine whether the packet is dropped or forwarded using
   the default set of network resources of the outgoing interface.  The
   Traffic Class field of the outer IPv6 header MAY be used to provide
   differentiated treatment for packets which belong to the same VTN.
   The egress node of the IPv6 domain MUST decapsulate the outer IPv6
   header and the Hop-by-Hop Options header which includes the VTN
   option.

   In the forwarding plane, there can be different approaches of
   partitioning the local network resources and allocating them to
   different VTNs.  For example, on one physical interface, a subset of
   the forwarding plane resources (e.g. bandwidth and the associated
   buffer and queuing resources) can be allocated to a particular VTN
   and represented as a virtual sub-interface with reserved bandwidth
   resource.  In packet forwarding, the IPv6 destination address of the
   received packet is used to identify the next-hop and the outgoing
   layer-3 interface, and the VTN Resource ID is used to further
   identify the virtual sub-interface on the outgoing interface which is
   associated with the VTN.










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   Network nodes which do not support the processing of Hop-by-Hop
   Options header SHOULD ignore the Hop-by-Hop options header and
   forward the packet only based on the destination IP address.  Network
   nodes which support Hop-by-Hop Options header, but do not support the
   VTN option SHOULD ignore the VTN option and continue to forward the
   packet based on the destination IP address.  The network node MAY
   process the rest of the Hop-by-Hop options in the Hop-by-Hop Options
   header.

4.  Operational Considerations

   As described in [RFC8200], network nodes may be configured to ignore
   the Hop-by-Hop Options header, drop packets containing a Hop-by-Hop
   Options header, or assign packets containing a Hop-by-Hop Options
   header to a slow processing path.  [I-D.ietf-6man-hbh-processing]
   specifies the modified procedures for the processing of IPv6 Hop-by-
   Hop Options header.  Operator needs to make sure that all the network
   nodes involved in a VTN can either process the Hop-by-Hop Options
   header in the fast path, or ignore the Hop-by-Hop Options header.
   Since a VTN is associated with a logical network topology, it is
   practical to ensure that all the network nodes involved in that
   logical topology support the processing of the Hop-by-Hop Options
   header and the VTN option.  In other word, packets steered into a VTN
   MUST NOT be dropped due to the existence of the Hop-by-Hop Options
   header.  It is RECOMMENDED to configure all the network nodes
   involved in a VTN to process the Hop-by-Hop Options header and the
   VTN option if there is a nob for this.

5.  IANA Considerations

   This document requests IANA to assign a new option type from
   "Destination Options and Hop-by-Hop Options" registry.

      Value          Description       Reference
      --------------------------------------------
       TBA           VTN Option      this document

6.  Security Considerations

   The security considerations with IPv6 Hop-by-Hop Options header are
   described in [RFC8200], [RFC7045], [RFC9098] and
   [I-D.ietf-6man-hbh-processing].  This document introduces a new IPv6
   Hop-by-Hop option which is either processed in the fast path or
   ignored by network nodes, thus it does not introduce additional
   security issues.

7.  Contributors




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      Zhibo Hu
      Email: huzhibo@huawei.com

      Lei Bao
      Email: baolei7@huawei.com

8.  Acknowledgements

   The authors would like to thank Juhua Xu, James Guichard, Joel
   Halpern, Tom Petch, Aijun Wang, Zhenqiang Li, Tom Herbert, Adrian
   Farrel and Eric Vyncke for their review and valuable comments.

9.  References

9.1.  Normative References

   [I-D.ietf-6man-hbh-processing]
              Hinden, R. M. and G. Fairhurst, "IPv6 Hop-by-Hop Options
              Processing Procedures", Work in Progress, Internet-Draft,
              draft-ietf-6man-hbh-processing-01, 7 July 2022,
              <https://www.ietf.org/archive/id/draft-ietf-6man-hbh-
              processing-01.txt>.

   [I-D.ietf-teas-enhanced-vpn]
              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for Enhanced Virtual Private Network (VPN+)
              Services", Work in Progress, Internet-Draft, draft-ietf-
              teas-enhanced-vpn-10, 6 March 2022,
              <https://www.ietf.org/archive/id/draft-ietf-teas-enhanced-
              vpn-10.txt>.

   [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>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8200]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", STD 86, RFC 8200,
              DOI 10.17487/RFC8200, July 2017,
              <https://www.rfc-editor.org/info/rfc8200>.

9.2.  Informative References





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   [I-D.dong-teas-nrp-scalability]
              Dong, J., Li, Z., Gong, L., Yang, G., Guichard, J. N.,
              Mishra, G., Qin, F., Saad, T., and V. P. Beeram,
              "Scalability Considerations for Network Resource
              Partition", Work in Progress, Internet-Draft, draft-dong-
              teas-nrp-scalability-02, 16 May 2022,
              <https://www.ietf.org/archive/id/draft-dong-teas-nrp-
              scalability-02.txt>.

   [I-D.ietf-lsr-flex-algo]
              Psenak, P., Hegde, S., Filsfils, C., Talaulikar, K., and
              A. Gulko, "IGP Flexible Algorithm", Work in Progress,
              Internet-Draft, draft-ietf-lsr-flex-algo-20, 18 May 2022,
              <https://www.ietf.org/archive/id/draft-ietf-lsr-flex-algo-
              20.txt>.

   [I-D.ietf-teas-ietf-network-slices]
              Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani,
              K., Contreras, L. M., and J. Tantsura, "Framework for IETF
              Network Slices", Work in Progress, Internet-Draft, draft-
              ietf-teas-ietf-network-slices-12, 30 June 2022,
              <https://www.ietf.org/archive/id/draft-ietf-teas-ietf-
              network-slices-12.txt>.

   [RFC4915]  Psenak, P., Mirtorabi, S., Roy, A., Nguyen, L., and P.
              Pillay-Esnault, "Multi-Topology (MT) Routing in OSPF",
              RFC 4915, DOI 10.17487/RFC4915, June 2007,
              <https://www.rfc-editor.org/info/rfc4915>.

   [RFC5120]  Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
              Topology (MT) Routing in Intermediate System to
              Intermediate Systems (IS-ISs)", RFC 5120,
              DOI 10.17487/RFC5120, February 2008,
              <https://www.rfc-editor.org/info/rfc5120>.

   [RFC7045]  Carpenter, B. and S. Jiang, "Transmission and Processing
              of IPv6 Extension Headers", RFC 7045,
              DOI 10.17487/RFC7045, December 2013,
              <https://www.rfc-editor.org/info/rfc7045>.

   [RFC9098]  Gont, F., Hilliard, N., Doering, G., Kumari, W., Huston,
              G., and W. Liu, "Operational Implications of IPv6 Packets
              with Extension Headers", RFC 9098, DOI 10.17487/RFC9098,
              September 2021, <https://www.rfc-editor.org/info/rfc9098>.







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   [RFC9099]  Vyncke, É., Chittimaneni, K., Kaeo, M., and E. Rey,
              "Operational Security Considerations for IPv6 Networks",
              RFC 9099, DOI 10.17487/RFC9099, August 2021,
              <https://www.rfc-editor.org/info/rfc9099>.

   [TS23501]  "3GPP TS23.501", 2016,
              <https://portal.3gpp.org/desktopmodules/Specifications/
              SpecificationDetails.aspx?specificationId=3144>.

Authors' Addresses

   Jie Dong
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Road
   Beijing
   100095
   China
   Email: jie.dong@huawei.com


   Zhenbin Li
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Road
   Beijing
   100095
   China
   Email: lizhenbin@huawei.com


   Chongfeng Xie
   China Telecom
   China Telecom Beijing Information Science & Technology, Beiqijia
   Beijing
   102209
   China
   Email: xiechf@chinatelecom.cn


   Chenhao Ma
   China Telecom
   China Telecom Beijing Information Science & Technology, Beiqijia
   Beijing
   102209
   China
   Email: machh@chinatelecom.cn






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   Gyan Mishra
   Verizon Inc.
   Email: gyan.s.mishra@verizon.com
















































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