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Versions: 00                                                            
Network Working Group                                              Z. Li
Internet-Draft                                                   J. Dong
Intended status: Standards Track                     Huawei Technologies
Expires: October 16, 2021                                 April 14, 2021


             Framework for End-to-End IETF Network Slicing
               draft-li-teas-e2e-ietf-network-slicing-00

Abstract

   Network slicing can be used to meet the connectivity and performance
   requirement of different services or customers in a shared network.
   An IETF network slice may span multiple network domains.  In the
   context of 5G, the 5G end-to-end network slices consist of three
   major types of network segments: Radio Access Network (RAN),
   Transport Network (TN) and Core Network (CN).

   In order to facilitate the mapping between network slices in
   different network segments and network domains, it is beneficial to
   carry the identifiers of the 5G end-to-end network slice, the multi-
   domain IETF network slice together with the intra-domain network
   slice identifier in the data packet.

   This document describes the framework of end-to-end IETF network
   slicing, and introduces the identifiers for 5G end-to-end network
   slice and the multi-domain IETF network slice in the data packet.
   The roles of the different identifiers in packet forwarding is also
   described.  The network slice identifiers can be instantiated with
   different data planes.

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/.





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   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 October 16, 2021.

Copyright Notice

   Copyright (c) 2021 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Framework . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Requirements on E2E IETF Network Slicing  . . . . . . . . . .   5
     3.1.  Data Plane  . . . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Management Plane/Control Plane  . . . . . . . . . . . . .   5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   6
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . .   6
     7.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   The definition and the characteristics of IETF network slice are
   introduced in [I-D.ietf-teas-ietf-network-slice-definition], and
   [I-D.ietf-teas-ietf-network-slice-framework] describes a general
   framework of IETF network slice.

   [I-D.ietf-teas-enhanced-vpn] describes the framework and the
   candidate component technologies for providing enhanced VPN services,
   by utilizing an approach that is based on existing VPN and Traffic
   Engineering (TE) technologies and adds characteristics that specific



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   services require above traditional VPNs.  VPN+ can be built from a
   VPN overlay and an underlying Virtual Transport Network (VTN) which
   has a customized network topology and a set of dedicated or shared
   resources in the underlay network.  Enhanced VPN (VPN+) can be used
   for the realization of IETF network slices.

   [I-D.dong-teas-enhanced-vpn-vtn-scalability] describes the
   scalability considerations in the control plane and data plane to
   enable VPN+ services, and provide several suggestions to improve the
   scalability of VTN.  In the control plane, It proposes the approach
   of decoupling the topology and resource attributes of VTN, so that
   multiple VTNs may share the same topology and the result of topology
   based path computation.  In the data plane, it proposes to carry a
   VTN-ID of a network domain in the data packet to determine the set of
   resources reserved for the corresponding VTN.

   An IETF network slice may span multiple network domains.  Further in
   the context of 5G, there can be end-to-end network slices which
   consists of three major types of network segments: Radio Access
   Network (RAN), Transport Network (TN) and Core Network (CN).  In
   order to facilitate the mapping between network slices in different
   network segments and network domains, it may be beneficial to also
   carry the identifiers of the 5G end-to-end network slice, the multi-
   domain IETF network slice together with the intra-domain network
   slice identifier in the data packet.

   This document describes the scenarios of end-to-end network slicing,
   and the framework of network slice mapping between different network
   segments and network domains.  Then multiple network slice related
   identifiers are defined to covers different network scopes.  These
   network slice identifiers can be instantiated using different data
   planes, such as MPLS and IPv6.

2.  Framework

















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    /----\        /----\         /----\          /----\         /----\
   /      \     //      \\     //      \\      //      \\      /      \
  |  RAN   |---|   TN-1   |---|   TN-2   |----|   TN-3   |----|  Core  |
   \      /     \\      //     \\      //      \\      //      \      /
    \----/        \----/         \----/          \----/         \----/

    S-NSSAI
  o--------------------------------------------------------------------o
             IETF Network Slice (VPN+)
           o--------------------------------------------------o
                Global VTN
              o===========================================o
                Local VTN-1   Local VTN-2      Local VTN-3
              o************o o************o   o***********o

Figure 1. 5G end-to-end network slicing scenario

   One typical scenario of 5G end-to-end network slicing is shown in
   figure 1.  The 5G end-to-end network slice is identified by the
   S-NSSAI (Single Network Slice Selection Assistance Information).  In
   the transport network segment, the 5G network slice is mapped to an
   IETF network slice, which is realized with a multi-domain VPN+
   service.  In the underlay network, the multi-domain VPN+ service is
   supported by a multi-domain VTN (Virtual Transport Network), which is
   comprised by multiple intra-domain VTNs in different domains.  In
   each domain, a local VTN-ID is carried in the packet to identify the
   set of network resource reserved for the VTN in the corresponding
   domain.

   In order to concatenate multiple local VTNs into a multi-domain VTN,
   the global VTN-ID can be carried in the packet, which is used by the
   network domain border routers to map to the local VTN-IDs in each
   domain.  And in order to facilitate the network slice mapping between
   RAN, Core network and transport network, the S-NSSAI may be carried
   in the packet sent to the transport network, which can be used by the
   transport network to map the 5G end-to-end network slice to the
   corresponding IETF network slice.

   According to the above end-to-end network slicing scenario, there can
   be three network slice related identifiers:

   o  Local VTN-ID: This is the VTN-ID as defined in
      [I-D.dong-teas-enhanced-vpn-vtn-scalability].  It is used by the
      network nodes in a network domain to determine the set of local
      network resources reserved for a VTN.  It SHOULD be processed by
      each hop along the path in the domain.





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   o  Global VTN-ID: This is the identifier which uniquely identifies a
      multi-domain VTN.  In each network domain, the domain edge node
      maps the global VTN-ID to a local VTN-ID for packet forwarding.

   o  5G end-to-end network slice ID (S-NSSAI): This is the identifier
      of the 5G end-to-end network slice.  When required, it can be used
      by the network nodes to provide traffic monitoring at the end-to-
      end network slice granularity.

   For the above network slice identifiers, the local VTN-ID is
   mandatory, the Global VTN-ID and the 5G S-NSSAI are optional.  The
   existence of the Global VTN-ID depends on whether the VTN spans
   multiple network domains in the transport network.  The existence of
   the 5G S-NSSAI depends on whether an IETF network slice is used as
   part of the 5G end-to-end network slice.

3.  Requirements on E2E IETF Network Slicing

   This section lists the requirements on E2E IETF network slicing.

3.1.  Data Plane

   To facilitate the mapping between 5G end-to-end network slice and
   IETF network slice, and the mapping between multi-domain IETF network
   slice and the intra-domain IETF network slice, different network
   slice related identifiers (e.g.  S-NSSAI, Global VTN-ID, local VTN-
   ID) needs to be carried in the data packet.

3.2.  Management Plane/Control Plane

   For multi-domain IETF network slice, a centralized IETF network slice
   controller is responsible for the allocation of the Global VTN-ID and
   the Local VTN-ID, and the provisioning mapping relationship of the
   Global VTN-ID and the Local VTN-IDs to the network edge nodes in
   different network domains.

   For 5G end-to-end network slice, the edge node of transport network
   can derive the S-NSSAI from the packet sent by the RAN or Core
   network, and encapsulate it an outer packet header or tunnel
   information when traversing the transport network.  The controller
   needs to be responsible for creating the mapping relationship and
   provisioning it to the edge nodes of the transport network.

4.  IANA Considerations

   This document makes no request of IANA.





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   Note to RFC Editor: this section may be removed on publication as an
   RFC.

5.  Security Considerations

   TBD

6.  Acknowledgements

   TBD

7.  References

7.1.  Normative References

   [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+)
              Service", draft-ietf-teas-enhanced-vpn-06 (work in
              progress), July 2020.

   [I-D.ietf-teas-ietf-network-slice-definition]
              Rokui, R., Homma, S., Makhijani, K., Contreras, L., and J.
              Tantsura, "Definition of IETF Network Slices", draft-ietf-
              teas-ietf-network-slice-definition-00 (work in progress),
              January 2021.

   [I-D.ietf-teas-ietf-network-slice-framework]
              Gray, E. and J. Drake, "Framework for IETF Network
              Slices", March 2021, <https://tools.ietf.org/html/draft-
              ietf-teas-ietf-network-slice-framework>.

   [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>.

7.2.  Informative References

   [I-D.dong-teas-enhanced-vpn-vtn-scalability]
              Dong, J., Li, Z., Qin, F., and G. Yang, "Scalability
              Considerations for Enhanced VPN (VPN+)", draft-dong-teas-
              enhanced-vpn-vtn-scalability-01 (work in progress),
              November 2020.







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Authors' Addresses

   Zhenbin Li
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Road
   Beijing  100095
   China

   Email: lizhenbin@huawei.com


   Jie Dong
   Huawei Technologies
   Huawei Campus, No. 156 Beiqing Road
   Beijing  100095
   China

   Email: jie.dong@huawei.com

































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