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Network Working Group                                            J. Dong
Internet-Draft                                                     Z. Li
Intended status: Standards Track                     Huawei Technologies
Expires: January 14, 2021                                         C. Xie
                                                                   C. Ma
                                                           China Telecom
                                                           July 13, 2020


 Carrying Virtual Transport Network Identifier in IPv6 Extension Header
                 draft-dong-6man-enhanced-vpn-vtn-id-01

Abstract

   This document proposes a new option type to carry virtual transport
   network identifier (VTN ID) in the IPv6 extensions headers to
   identify the Virtual Transport Network (VTN) the packet belongs to.
   The procedure of processing the VTN option is also specified.  This
   provides a scalable solution for data plane encapsulation of enhanced
   VPN (VPN+) as described in I-D.ietf-teas-enhanced-vpn.  One typical
   use case of VPN+ is to provide transport network slicing in 5G, while
   it could also be used in more general cases.

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
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   This Internet-Draft will expire on January 14, 2021.

Copyright Notice

   Copyright (c) 2020 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



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   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.  Requirements Language . . . . . . . . . . . . . . . . . . . .   3
   3.  New IPv6 Extension Header Option for VTN  . . . . . . . . . .   3
   4.  Procedures  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.1.  VTN Option Insertion  . . . . . . . . . . . . . . . . . .   4
     4.2.  VTN based Packet Forwarding . . . . . . . . . . . . . . .   4
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .   5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     10.2.  Informative References . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   Virtual private networks (VPNs) have served the industry well as a
   means of providing different groups of users with logically isolated
   connectivity over a common network.  Some customers may request a
   connectivity services with advanced characteristics such as complete
   isolation from other services or guaranteed performance.  These
   services are "enhanced VPNs" (known as VPN+).
   [I-D.ietf-teas-enhanced-vpn] describes the framework and candidate
   component technologies for providing enhanced VPN services.  One
   typical use case of VPN+ is to provide transport network slicing in
   5G, while it could also be used in more general cases.

   The enhanced properties of VPN+ require tighter coordination and
   integration between the underlay network resources and the overlay
   network.  VPN+ service is built on a Virtual Transport Network (VTN)
   which has a customized network topology and a set of dedicated or
   shared network resources allocated from the underlay network.  The
   overlay VPN together with the corresponding VTN in the underlay
   provide the VPN+ service.  In the network, traffic of different VPN+
   services need to be processed separately based on the topology and
   the network resources associated with the corresponding VTN.




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   [I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the
   scalability considerations of enhanced VPN, in which one approach to
   improve the data plane scalability is to introduce a dedicated
   identifier indata packet to identify the VTN the packet belongs to,
   so as to perform resource specific packet processing.  This is called
   Resource Independent (RI) VTN.

   This document proposes a mechanism to carry the VTN Identifier (VTN
   ID) in the IPv6 extensions headers [RFC8200] of packet, so that the
   packet will be processed by network nodes using the network resources
   allocated to the corresponding VTN.  The procedure of processing the
   VTN ID is also specified.  This provides a scalable solution for
   enhanced VPN data plane, so that it could be used to support a large
   number of transport network slices in IPv6 network.

2.  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.

3.  New IPv6 Extension Header Option for VTN

   A new option type of IPv6 extension headers is defined to carry the
   Virtual Transport Network Identifier (VTN ID) in IPv6 packet header.
   Its format is shown as below:

              Option   Option       Option
               Type   Data Len       Data
            +--------+--------+--------+--------+
            |BBCTTTTT|00000100|  4-octet VTN ID |
            +--------+--------+--------+--------+

   Option Type: 8-bit identifier of the type of option.  The type of VTN
   option is TBD by IANA.  The highest-order bits of the type field are
   defined as below:

   o  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.

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






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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 4.

   Option Data: 4-octet VTN which uniquely identifies a virtual
   transport network.

   Editor's note: The length of the VTN ID is defined as 4-octet
   partially for the matching with the 4-octet network slice identifier
   defined in 3GPP [TS23501].

                      8-bit              24-bit
                  +------------+-------------------------+
                  |    SST     |   Slice Differentiator  |
                  +------------+-------------------------+

4.  Procedures

4.1.  VTN Option Insertion

   When an ingress node of an IPv6 or SRv6 domain receives a packet,
   according to traffic classification or mapping policy, the packet
   SHOULD be encapsulated in an outer IP header, and the VTN-ID of the
   virtual transport network which the traffic is mapped to SHOULD be
   carried in the extension header associated with the outer IPv6 header
   . The ingress node MAY also encapsulate the SRH as defined in
   [RFC8754] in the Routing Header of the outer IPv6 header.

   In order to make the VTN option be processed by each node along the
   path, it is RECOMMENDED that the VTN option be carried in IPv6
   extension headers which can be processed hop-by-hop in forwarding
   plane.  It can be carried in either the Hop-by-Hop Options header, or
   some new extension headers which can be processed on each hop along
   the path.

4.2.  VTN based Packet Forwarding

   On receipt of a packet with the VTN option, each network node which
   can parse the VTN option SHOULD use the VTN ID to identify the
   virtual network the packet belongs to.  This means the forwarding
   behavior is based on both the destination IP address and the VTN
   option.The destination IP address is used for the lookup of the next-
   hop node, and VTN-ID can be used to determine the set of network
   resources reserved for processing and sending the packet to the next-
   hop node.  The domain egress node SHOULD decapsulate the outer IPv6
   header.





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   There can be different implementations of reserving local network
   resources to the VTNs.  On each interface, the resources allocated to
   a particular VTN can be seen as a virtual sub-interface with
   dedicated bandwidth and other associated resources.  In packet
   forwarding, the IPv6 destination address of the received packet is
   used to identify the next-hop and the outgoing interface, and the VTN
   ID is used to further identify the virtual sub-interface which is
   associated with the VTN on the outgoing interface.

   Routers which do not support Hop-by-Hop options header SHOULD ignore
   the Hop-by-Hop options header and forward the packet merely based on
   the destination IP address.  Routers which support Hop-by-Hop
   Options, but do not recognize the VTN option SHOULD ignore the option
   and continue to forward the packet merely based on the destination IP
   address.

5.  Operational Considerations

   As described in [RFC8200], nodes may be configured to ignore the Hop-
   by-Hop Options header, and the packets containing a Hop-by-Hop
   Options header may be dropped or assigned to a slow processing path.
   When VTN option is carried in Hop-by-Hop option header, operator
   needs to make sure that all the network nodes involved in the VTN can
   either process the Hop-by-Hop Options header in packet forwarding, or
   ignore the Hop-by-Hop Option header but continue to forward the
   packet based on other fields and headers.  In other words, Packet
   mapping to a VTN MUST NOT be dropped due to the existence of the Hop-
   by-Hop Options header.  It is RECOMMENDED to configure the nodes to
   process the Hop-by-Hop Option header if there is a nob for this.

6.  IANA Considerations

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

      Value   Description                             Reference
      ------------------------------------------------------------
      TBD     Virtual Transport Network Identifier   this document

7.  Security Considerations

   TBD

8.  Contributors







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      Zhibo Hu
      Email: huzhibo@huawei.com

      Lei Bao
      Email: baolei7@huawei.com

9.  Acknowledgements

   The authors would like to thank Juhua Xu for his review and valuable
   comments.

10.  References

10.1.  Normative References

   [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.dong-teas-enhanced-vpn-vtn-scalability]
              Dong, J., Li, Z., and F. Qin, "Virtual Transport Network
              (VTN) Scalability Considerations for Enhanced VPN", draft-
              dong-teas-enhanced-vpn-vtn-scalability-00 (work in
              progress), February 2020.

   [I-D.ietf-teas-enhanced-vpn]
              Dong, J., Bryant, S., Li, Z., Miyasaka, T., and Y. Lee, "A
              Framework for Enhanced Virtual Private Networks (VPN+)
              Services", draft-ietf-teas-enhanced-vpn-05 (work in
              progress), February 2020.

   [RFC8754]  Filsfils, C., Ed., Dukes, D., Ed., Previdi, S., Leddy, J.,
              Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header
              (SRH)", RFC 8754, DOI 10.17487/RFC8754, March 2020,
              <https://www.rfc-editor.org/info/rfc8754>.




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   [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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