Carrying Network Resource Partition (NRP) Information in IPv6 Extension Header
draft-ietf-6man-enhanced-vpn-vtn-id-06

Network Working Group                                            J. Dong
Internet-Draft                                                     Z. Li
Intended status: Standards Track                     Huawei Technologies
Expires: 23 August 2024                                           C. Xie
                                                                   C. Ma
                                                           China Telecom
                                                               G. Mishra
                                                            Verizon Inc.
                                                        20 February 2024

Carrying Network Resource Partition (NRP) Information in IPv6 Extension
                                 Header
                 draft-ietf-6man-enhanced-vpn-vtn-id-06

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 also
   in some existing network scenarios, some customers may require
   network connectivity services with advanced features comparing to
   conventional VPN services.  Such kind of network service is called
   enhanced VPNs.  Enhanced VPNs can be used, for example, to deliver
   network slice services.

   A Network Resource Partition (NRP) is a subset of the network
   resources and associated policies on each of a connected set of links
   in the underlay network.  An NRP could be used as the underlay to
   support one or a group of enhanced VPN services.  For packet
   forwarding in a specific NRP, some fields in the data packet are used
   to identify the NRP the packet belongs to, so that NRP-specific
   processing can be performed on each node along a path in the NRP.

   This document specifies a new IPv6 Hop-by-Hop option to carry the NRP
   related information in data packets, which could be used to identify
   the NRP-specific processing to be performed on the packets by each
   network node along a network path in the NRP.

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/.

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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on 23 August 2024.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
   2.  New IPv6 Extension Header Option for NRP  . . . . . . . . . .   4
   3.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Adding NRP Option to Packets  . . . . . . . . . . . . . .   6
     3.2.  NRP-specific Packet Forwarding  . . . . . . . . . . . . .   6
   4.  Operational Considerations  . . . . . . . . . . . . . . . . .   7
   5.  Considerations about Generalization . . . . . . . . . . . . .   7
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   9
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   9
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11

1.  Introduction

   Virtual Private Networks (VPNs) [RFC4026] provide different customers
   with logically isolated connectivity over a common network
   infrastructure.  With the introduction and evolvement of 5G and also
   in some existing network scenarios, some customers may require
   network connectivity services with advanced features comparing to
   conventional VPNs, such as resource isolation from other services or

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   guaranteed performance.  Such kind of network service is called
   enhanced VPN [I-D.ietf-teas-enhanced-vpn].  Enhanced VPN service
   requires the coordination and integration between the overlay VPNs
   and the capability and resources of the underlay network.  Enhanced
   VPN can be used, for example, to deliver IETF network slice services
   [I-D.ietf-teas-ietf-network-slices].

   [I-D.ietf-teas-ietf-network-slices] also introduces the concept of
   the Network Resource Partition (NRP), which is a subset of the
   buffer/queuing/scheduling resources and associated policies on each
   of a connected set of links in the underlay network.  An NRP can be
   associated with a logical network topology to select or specify the
   set of links and nodes involved.

   [I-D.ietf-teas-enhanced-vpn] specifies the framework of NRP-based
   enhanced VPN and describes the candidate component technologies in
   different network planes and network layers.  An NRP could be used as
   the underlay to meet the requirement of one or a group of enhanced
   VPN services.

   In packet forwarding, traffic of different Enhanced VPN services
   needs to be processed separately based on the network resources and
   the logical topology associated with the corresponding NRP.
   [I-D.ietf-teas-nrp-scalability] describes the scalability
   considerations and the possible optimizations for providing a
   relatively large number of NRPs.  One approach to improve the data
   plane scalability of NRP is to introduce a dedicated NRP ID in the
   data packet to identify the set of network resources allocated to an
   NRP, so that packets in an NRP can be processed and forwarded using
   the NRP-specific network resources, which could avoid possible
   resource competition with services in other NRPs.  An NRP ID can have
   network resource semantics, which 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 of an NRP could be defined and
   identified using mechanisms such as Multi-Topology [RFC4915],
   [RFC5120] or Flex-Algo [RFC9350].

   This document specifies a mechanism to carry NRP related information
   in a new IPv6 Hop-by-Hop option (Section 4.3 of [RFC8200]) called
   "NRP option".  The NRP option is parsed by every intermediate node
   along the forwarding path, and the obtained NRP ID is used to invoke
   NRP-specific packet processing and forwarding using the set of NRP-
   specific resources.  This provides a scalable solution to support a
   relatively large number of NRPs in an IPv6 network
   [I-D.ietf-teas-nrp-scalability].

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   Although in this document the application of the NRP option is to
   indicate the NRP-specific resource information, the NRP option is
   considered as a generic mechanism to convey network wide NRP ID and
   information with different semantics to meet the possible use cases
   in the future.  Some considerations about generalization are
   described in Section 5.

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 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  New IPv6 Extension Header Option for NRP

   A new Hop-by-Hop option (Section 4.3 of [RFC8200]) type "NRP" is
   defined to carry the NRP related information.  Its format is shown in
   Figure 1.

        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
                                       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                                       |  Option Type  |  Opt Data Len |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |     Flags     | Context Type  |            Reserved           |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       ~                            NRP ID                             ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 1. The format of NRP Option

   Option Type: 8-bit identifier of the type of option.  The type of NRP
   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.

   Opt Data Len: 8-bit unsigned integer indicates the length of the
   option Data field of this option, in octets.

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   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 NRP
      ID MUST be strictly matched for the processing of the packet.  It
      provides an approach for fine granular control of packet
      forwarding behavior when the NRP ID is not matched.  If the NRP ID
      in the NRP option does not match with any of the NRP ID
      provisioned on the network node and the S flag is set to 1, the
      packet MUST be dropped.  If the NRP ID does not match with any of
      the NRP ID provisioned on the network node and the S flag is set
      to 0, the packet MUST be forwarded using the default behavior as
      if the NRP option does not exist.

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

   Context Type (CT): One-octet field used to indicate the semantics and
   length of the NRP ID carried in the option.  The context value
   defined in this document is as follows:

   *  CT=0: The NRP ID is a 4-octet network-wide unique resource ID,
      which is used to identify the subset of network resources
      allocated to the NRP on the involved network nodes and links.

   Reserved: 2-octet field reserved for future use.  They MUST be set to
   0 on transmission and MUST be ignored on receipt.

   NRP ID: The identifier of a Network Resource Partition, the semantics
   and length of the ID is determined by the Context Type.

   Note that, in the context of 5G network slicing, if a deployment
   found it useful, the four-octet NRP ID field may be derived from the
   four-octet Single Network Slice Selection Assistance Information
   (S-NSSAI) defined in 3GPP [TS23501].

3.  Procedures

   This section describes the procedures for NRP option processing when
   the Context Type in the NRP option is set to 0.  The processing
   procedures for NRP option with other Context Types are out of the
   scope of this document and will be specified in separate documents
   which introduce those Context Types.

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3.1.  Adding NRP Option to Packets

   When an ingress node of an IPv6 domain receives a packet, according
   to the traffic classification and mapping policy, the packet needs to
   be steered into one of the NRPs in the network, then the packet MUST
   be encapsulated in an outer IPv6 header with the source and
   destination addresses set according to the policy, and the NRP ID of
   the NRP which the packet is mapped to according to the policy MUST be
   carried in the NRP option of the Hop-by-Hop Options header, which is
   associated with the outer IPv6 header.

3.2.  NRP-specific Packet Forwarding

   On receipt of a packet with the NRP option, each network node which
   can process the Hop-by-Hop Options header and the NRP option in fast
   path [I-D.ietf-6man-hbh-processing] MUST use the NRP ID to determine
   the set of local network resources which are allocated to the NRP.
   The packet forwarding behavior is based on both the destination IP
   address and the NRP ID.  More specifically, the destination IP
   address SHOULD be used to determine the next-hop and the outgoing
   interface, and NRP ID SHOULD be used to determine the set of network
   resources on the outgoing interface which are allocated to the NRP
   for processing and sending the packet.  If the NRP ID does not match
   with any of the NRP ID provisioned on the outgoing interface, the S
   flag in the NRP option SHOULD be used to determine whether the packet
   should be 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 NRP.  The egress node of the IPv6
   domain MUST decapsulate the outer IPv6 header and the Hop-by-Hop
   Options header which includes the NRP option.

   In the forwarding plane, there can be different approaches of
   partitioning the local network resources and allocating them to
   different NRPs.  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 NRP
   and represented as a virtual sub-interface or a data channel 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 NRP ID is used
   to further identify the virtual sub-interface or the data channel on
   the outgoing interface which is associated with the NRP.

   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

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   NRP option SHOULD ignore the NRP option and forward the packet only
   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.  In networks with such network
   nodes, it is important that packets of an NRP are not dropped due to
   the existence of the Hop-by-Hop Options header.  Operators need to
   make sure that all the network nodes involved in an NRP can either
   process the Hop-by-Hop Options header in the fast path, or ignore the
   Hop-by-Hop Options header.  Since an NRP is associated with a logical
   network topology, one practical approach is to ensure that all the
   network nodes involved in that logical topology support the
   processing of the Hop-by-Hop Options header and the NRP option in the
   fast path, and constrain the packet forwarding path to the logical
   topology of the NRP.

   [I-D.ietf-6man-hbh-processing] specifies the modified procedures for
   the processing of IPv6 Hop-by-Hop Options header, with the purpose of
   making the Hop-by-Hop Options header useful.  Network nodes complying
   with [I-D.ietf-6man-hbh-processing] will not drop packets with Hop-
   by-Hop Options header and the NRP option.

5.  Considerations about Generalization

   During the discussion of this document in the 6MAN WG, one of the
   suggestions received is to make the NRP option more generic in terms
   of semantics and encoding.  This section gives some analysis about to
   what extent the semantics of NRP could be generalized, and how the
   generalization could be achieved with the proposed encoding.

   Based on the NRP definition in [I-D.ietf-teas-ietf-network-slices],
   the concept of NRP could be extended as: an underlay network
   construct which is associated with a set of network-wide attributes
   and states maintained on each participating network node.  The
   attributes associated with an NRP may include but not limited to:
   network resource attributes, network topology attributes, and network
   function attributes etc.

   *  The network resource can refer to various type of data plane
      resources, including link bandwidth, bufferage and queueing
      resources.

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   *  The network topology can be multipoint-to-multipoint, point-to-
      point, point-to-multipoint or multipoint-to-point.

   *  The network functions may include both data forwarding actions and
      other types network functions which can be executed on data
      packets mapped to an NRP.

   This shows the semantics of NRP can be quite generic.  Although
   generalization is something good to have, it would be important to
   understand and identify the boundary of generalization.  In this
   document, It is anticipated that for one network attribute to be
   included in NRP, it needs to be a network-wide attribute rather than
   a node-specific attribute.  Thus whether a network-wide view can be
   provided or not could be considered as one prerequisite of making one
   attribute part of the NRP option.

   The format of the NRP option contains the Flags field, the Context
   Type field and the Reserved field, which provide the capability for
   future extensions.  That said, since the NRP option needs to be
   processed by network nodes in the fast path, the capability of
   network devices need to be considered when new semantics and encoding
   are introduced.

6.  IANA Considerations

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

      Hex Value      Binary Value      Description      Reference
                     act chg rest
      -----------------------------------------------------------
         TBA         00   0  tba       NRP Option      [this document]

   This document requests IANA to create a new registry for the "NRP
   Option Context Type" under the "Internet Protocol Version 6 (IPv6)
   Parameters" registry.  The allocation policy of this registry is
   "Standards Action".  The initial codepoints are assigned by this
   document as follows:

      Value          Description       Reference
      -----------------------------------------------
        0            Resource ID      [this document]
      1-254          Unassigned
       255           Reserved         [this document]

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7.  Security Considerations

   The security considerations with IPv6 Hop-by-Hop Options header are
   described in [RFC8200], [RFC7045], [RFC9098] [RFC9099] 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.

8.  Contributors

      Zhibo Hu
      Email: huzhibo@huawei.com

      Lei Bao
      Email: baolei7@huawei.com

9.  Acknowledgements

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

10.  References

10.1.  Normative References

   [I-D.ietf-teas-enhanced-vpn]
              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for NRP-based Enhanced Virtual Private Network",
              Work in Progress, Internet-Draft, draft-ietf-teas-
              enhanced-vpn-17, 25 December 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
              enhanced-vpn-17>.

   [I-D.ietf-teas-ietf-network-slices]
              Farrel, A., Drake, J., Rokui, R., Homma, S., Makhijani,
              K., Contreras, L. M., and J. Tantsura, "A Framework for
              Network Slices in Networks Built from IETF Technologies",
              Work in Progress, Internet-Draft, draft-ietf-teas-ietf-
              network-slices-25, 14 September 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
              ietf-network-slices-25>.

   [IANA-HBH] "IANA, "Destination Options and Hop-by-Hop Options"",
              2016, <https://www.iana.org/assignments/ipv6-parameters/>.

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   [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>.

10.2.  Informative 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-13, 18 February 2024,
              <https://datatracker.ietf.org/api/v1/doc/document/draft-
              ietf-6man-hbh-processing/>.

   [I-D.ietf-teas-nrp-scalability]
              Dong, J., Li, Z., Gong, L., Yang, G., Mishra, G. S., and
              F. Qin, "Scalability Considerations for Network Resource
              Partition", Work in Progress, Internet-Draft, draft-ietf-
              teas-nrp-scalability-03, 21 October 2023,
              <https://datatracker.ietf.org/doc/html/draft-ietf-teas-
              nrp-scalability-03>.

   [RFC4026]  Andersson, L. and T. Madsen, "Provider Provisioned Virtual
              Private Network (VPN) Terminology", RFC 4026,
              DOI 10.17487/RFC4026, March 2005,
              <https://www.rfc-editor.org/info/rfc4026>.

   [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>.

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   [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>.

   [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>.

   [RFC9350]  Psenak, P., Ed., Hegde, S., Filsfils, C., Talaulikar, K.,
              and A. Gulko, "IGP Flexible Algorithm", RFC 9350,
              DOI 10.17487/RFC9350, February 2023,
              <https://www.rfc-editor.org/info/rfc9350>.

   [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

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   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

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

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