Internet Engineering Task Force                            S. Matsushima
Internet-Draft                                                 K. Horiba
Intended status: Standards Track                                 A. Khan
Expires: 8 September 2022                                    Y. Kawakami
                                                                SoftBank
                                                             T. Murakami
                                                                K. Patel
                                                             Arrcus, Inc
                                                                M. Kohno
                                                               T. Kamata
                                                            P. Camarillo
                                                     Cisco Systems, Inc.
                                                                D. Voyer
                                                             Bell Canada
                                                                S. Zadok
                                                               I. Meilik
                                                                Broadcom
                                                              A. Agrawal
                                                              K. Perumal
                                                                   Intel
                                                                 J. Horn
                                                     Cisco Systems, Inc.
                                                            7 March 2022


  Segment Routing IPv6 Mobile User Plane Architecture for Distributed
                          Mobility Management
                 draft-mhkk-dmm-srv6mup-architecture-02

Abstract

   This document defines the Segment Routing IPv6 Mobile User Plane
   (SRv6 MUP) architecture for Distributed Mobility Management.  The
   requirements for Distributed Mobility Management described in
   [RFC7333] can be satisfied by routing fashion.

   Mobile services are deployed over several parts of IP networks.  A
   Segment Routing over IPv6 (SRv6) network can accommodate all, or part
   of those networks thanks to the large address space of IPv6 and the
   network programming capability described in [RFC8986].

   Segment Routing IPv6 Mobile User Plane Architecture can incorporate
   existing session based mobile networks.  By leveraging SRv6 network
   programmability, mobile user plane can be integrated into the SRv6
   data plane.  In that routing paradigm, session information between
   the entities of the mobile user plane is turned to routing
   information.




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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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   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 September 2022.

Copyright Notice

   Copyright (c) 2022 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
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Architecture Overview . . . . . . . . . . . . . . . . . . . .   5
   4.  Mobile User Plane Segment . . . . . . . . . . . . . . . . . .   6
   5.  Distribution of Mobile User Plane Segment Information . . . .   7
     5.1.  MUP PE  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.2.  MUP GW  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   6.  MUP Controller  . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  Illustration  . . . . . . . . . . . . . . . . . . . . . . . .   9
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  16
     10.2.  Informative References . . . . . . . . . . . . . . . . .  16



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   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   Mobile services require IP connectivity for communication between the
   entities of mobile service architecture [RFC5213][TS.23501].  To
   provide the IP connectivity, Segment Routing (SR) [RFC8402]can be a
   candidate solution.

   In PMIPv6 [RFC5213], IP connectivity between LMA and MAG can be
   provided over SR networks, as well as LMA and Internet.  In 3GPP 5G
   [TS.23501], IP connectivity for N3 interface between gNodeB(es) and
   UPFs can also be provided by SR, as well as for N6 interface between
   UPFs and DNs (Data Network).

   These IP connectivities may be covered by multiple SR networks, or
   just one SR network, depending on the size of the deployment.  In the
   latter case, it is expected that the address space of the SR network
   should be large enough to cover a vast number of nodes, such as
   millions of base stations.  For this reason, use of IPv6 for the SR
   dataplane looks sufficiently suitable.

   SRv6 is an instantiation of SR over IPv6 dataplane in which a single
   network can accommodate all entities of mobile services thanks to the
   huge available address space and network programming capability
   described in [RFC8986].

   Meanwhile, SRv6 network programmability enhances SRv6 dataplane to be
   integrated with mobile user plane [I-D.ietf-dmm-srv6-mobile-uplane].
   It will make an entire SRv6 network support the user plane in a very
   efficient distributed routing fashion.

   On the other hand, the requirements for Distributed Mobility
   Management (DMM) described in [RFC7333] can be satisfied by session
   management based solutions.  [RFC8885] defines protocol extension to
   PMIPv6 for the DMM requirements.  3GPP 5G defines an architecture in
   which multiple session anchors can be added to one mobility session
   by the session management.

   As a reminder, the user plane related requirements in [RFC7333] are
   reproduced here:

   REQ1: Distributed mobility management
           IP mobility, network access solutions, and forwarding
           solutions provided by DMM MUST enable traffic to avoid
           traversing a single mobility anchor far from the optimal
           route.  It is noted that the requirement on distribution
           applies to the data plane only.



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   REQ3: IPv6 deployment
           DMM solutions SHOULD target IPv6 as the primary deployment
           environment and SHOULD NOT be tailored specifically to
           support IPv4, particularly in situations where private IPv4
           addresses and/or NATs are used.

   REQ4: Existing mobility protocols
           A DMM solution MUST first consider reusing and extending IETF
           standard protocols before specifying new protocols.

   REQ5: Coexistence with deployed networks/hosts and operability
   across different networks
           A DMM solution may require loose, tight, or no integration
           into existing mobility protocols and host IP stacks.
           Regardless of the integration level, DMM implementations MUST
           be able to coexist with existing network deployments, end
           hosts, and routers that may or may not implement existing
           mobility protocols.  Furthermore, a DMM solution SHOULD work
           across different networks, possibly operated as separate
           administrative domains, when the needed mobility management
           signaling, forwarding, and network access are allowed by the
           trust relationship between them.

   This document defines the Segment Routing IPv6 Mobile User Plane
   (SRv6 MUP) architecture for Distributed Mobility Management.  SRv6
   MUP is not a mobility management system itself, but an architecture
   to integrate mobile user plane into the SRv6 data plane.

   In this routing paradigm, session information from a mobility
   management system will be transformed to routing information.  It
   means that mobile user plane specific nodes for the anchor or
   intermediate points are no longer required.  The user plane anchor
   and intermediate functions can be supported by SR throughout an SR
   domain (REQ1), not to mention that SRv6 MUP will naturally be
   deployed over IPv6 networks (REQ3).

   SRv6 MUP architecture is independent from the mobility management
   system.  For the requirements (REQ4, 5), SRv6 MUP architecture is
   designed to be pluggable user plane part of existing mobile service
   architectures.  Those existing architectures are for example defined
   in [RFC5213], [TS.23501], or if any.

   The level of SRv6 MUP integration for mobile networks running based
   on the existing architecture will be varied and depending on the
   level of SRv6 awareness of the control and user plane entities.






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   Specifying how to modify the existing architecture to integrate SRv6
   MUP is out of scope of this document.  What this document provides
   for the existing architecture is an interface for SRv6 MUP which the
   existing or future architectures can easily integrate.

1.1.  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].

2.  Terminology

   MUP:    Mobile User Plane

   MUP Segment:  Representation of mobile user plane segment

   MUP PE:  Provider Edge node in a MUP network

   MUP GW:  Gateway node to interwork with another mobile user plane
           networks

   MUP Controller:  Controller node for a MUP network

   UE:     User Equipment, as per [TS.23501]

   MN:     Mobile Node, as per [RFC5213]

3.  Architecture Overview

   SRv6 MUP architecture defined in this document introduces a new
   segment type of the SR called "Mobile User Plane (MUP) segment" and
   new routing information called "Segment Discovery route" and "Session
   Transformed route", then 3 new network nodes; MUP PE, MUP GW and MUP
   Controller.  Figure 1 depicts the overview.

   To carry these new routing information, this architecture requires
   extending the existing routing protocols.  Any routing protocol can
   be used to carry this information but this document recommends using
   BGP.  Thus, this document describes extensions on BGP as an example.











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                            *   Mobility   *
                             * Management *
                              *  System  *
                               *........*
                                   |
                           Session Information
                                   |
                                   v
                           +----------------+
                         --| MUP Controller |--            ___________
                        /  +----------------+  \          /           \
    ___________        /         _______    +--------+   /             \
   /           \      /         /       \---| MUP PE |---\ MUP Segment /
  /             \  +--------+  /         \  +--------+    \___________/
  \ MUP Segment /--| MUP GW |--\ SRv6 NW /  +--------+     ___________
   \___________/   +--------+   \_______/---| MUP PE |----/           \
                                            +--------+   /             \
                                                         \ MUP Segment /
                                                          \___________/


               Figure 1: Overview of SRv6 MUP Architecture

4.  Mobile User Plane Segment

   This document defines one new segment type.  A Mobile User Plane
   (MUP) segment may represent a network segment consisting of a mobile
   service.  The MUP segment can be created by an SR node which provides
   connectivity for the mobile user plane.  The MUP segment SID can be
   any behavior defined in [RFC8986], [I-D.ietf-dmm-srv6-mobile-uplane],
   or any other extensions for further use cases.

   The behavior of the MUP segment will be chosen by the role of the
   representing mobile network segment.  For example, in case of an SR
   node interfaces to 5G user plane on the access side defined as "N3"
   in [TS.23501], the behavior of created segment SID will be
   "End.M.GTP4.E", or "End.M.GTP6.E".  In this case, the SR node may
   associate the SID to a N3 access network (N3RAN) routing instance.

   Another example here is the "N6" interface on the core data network
   side.  The behavior of the created segment SID will be "End.DT4",
   "End.DT6", or "End.DT2".  In this case the SR node may associate the
   SID to a N6 data network (N6DN) routing instance.








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5.  Distribution of Mobile User Plane Segment Information

   Distribution of MUP segment information can be done by advertising
   routing information with the MUP segment for mobile service.  This
   document defines two types of SR node, MUP PE and MUP GW, for
   distributing MUP segment information.

   A MUP Segment Discovery route is routing information, of which a MUP
   segment is associated with network reachability.  This document
   defines the basic discovery route types, Direct Segment Discovery
   route, and Interwork Segment Discovery route.  Other types of segment
   discovery route may be mobile service architecture specific.  Define
   the architecture specific network reachability is out of scope of
   this document and it will be specified in another document.

5.1.  MUP PE

   A MUP PE accommodates a MUP Segment to a routing instance for MUP
   Direct Segment.  The MUP PE advertises the Direct Segment Discovery
   route for the routing instance.  The Direct Segment Discovery route
   includes an address of the MUP PE in the network reachability
   information with the corresponding Direct Segment indicating
   community, and SID of the routing instance to the SR domain.

   For example in 3GPP 5G specific case, an MUP PE may connect to N6
   interface on a DN side, an MUP Segment Discovery route for the DN
   will be advertised with an address of the MUP PE, corresponding SID
   and Direct Segment indicating community to the routing instance for
   the DN from the MUP PE.

   When a MUP PE receives a Interwork Segment Discovery route, the MUP
   PE keeps the received Interwork Segment Discovery routes in the RIB.
   The MUP PE uses the received Interwork Segment Discovery routes to
   resolve the reachability for remote endpoint of Type 1 session
   transformed routes, described in Section 6.  If the Interwork Segment
   Discovery route resolves the reachability for Type 1 session
   transformed routes, the MUP PE updates the FIB entry for the prefix
   of Type 1 session transformed route with the SID of the matched MUP
   segment discovery route.












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   The received Interwork Segment Discovery routes MUST be used only to
   resolve reachability for the remote endpoints of Type 1 session
   transformed routes.  The connectivity among the routing instances for
   Interwork Segments may be advertised as VPN routes.  This is to avoid
   forwarding entries to the prefixes of Interwork Segment mingled in
   the other type of routing instance.  A SR node MAY discard the
   received Interwork segment discovery route if the Route Target
   extended communities of the route does not meet the SR node's import
   poilicy.

5.2.  MUP GW

   A MUP GW interfaces an Interwork Segment with the user plane protocol
   for the existing mobile service architecture.  The MUP GW
   accommodates the Interwork Segment to a routing instance for the
   existing mobile service architecture.  The MUP GW advertises the
   corresponding Interwork Segment Discovery route with the prefixes of
   the Interwork Segment and the corresponding SID of the prefixes to
   the SR domain.

   For example in 3GPP 5G specific case, an Interwork Segment Discovery
   route for N3 network accommodating RAN will be incorporated in an
   N3RAN segment discovery route associated with a RAN segment SID.

   When a MUP GW receives a Direct Segment Discovery route from MUP PEs,
   the MUP GW keeps the received Direct Segment Discovery route in the
   RIB.  The MUP GW uses the received Direct Segment Discovery route to
   resolve Type 2 session transformed routes reachability, described in
   Section 6.  If the Direct Segment Discovery route resolves
   reachability for the endpoints, and match the Direct Segment
   indication community of the Type 2 session transformed routes, the
   MUP GW updates the FIB entry for the Type 2 session transformed route
   with the SID of the matched MUP segment discovery route.

   In case that an SR node accommodates MUP GW and PE simultaneously,
   the MUP GW in the SR node uses a local Direct Segment routing
   instance if a received Type 2 session transformed route indicates the
   local Direct Segment routing instance by the Direct Segment
   indicating community in the Type 2 session transformed route.

6.  MUP Controller

   A MUP controller provides a northbound API.  A consumer of the API
   inputs session information for a UE or a MN from mobility management
   system.  The MUP controller transforms the received session
   information to routing information and will advertise the transformed
   route to the SR domain.




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   The received session information is expected to include the UE or MN
   IP prefix(es), tunnel endpoint identifiers for both ends, and any
   other attributes for the mobile networks.  For example in a 3GPP 5G
   specific case, the tunnel endpoint identifier will be a pair of the
   F-TEIDs on both the N3 access side (RAN) and core side (UPF).

   SRv6 MUP architecture defines two types of session transformed route.

   First type route is that IP prefix(es) for a UE or MN may be encoded
   in a BGP MP-NLRI attribute with associated session information of the
   tunnel endpoint identifier on the access side.  The MUP controller
   advertises the UE or MN route to the SR domain.

   Second type route is that the tunnel endpoint identifier of the
   session on the core side may also be encoded in another BGP MP-NLRI
   attribute with the nature of tunnel decapsulation.  Longest match
   algorithm for the prefix in this type of session transformed route
   should be applicable to aggregate the routes for scale.

   MUP PE and GW are expected to receive the routes advertised from the
   MUP controller.  A MUP PE imports a Type 1 session transformed route
   for UE or MN into the corresponding Direct type routing instance.  A
   MUP GW imports a Type 2 session transformed route for core side
   session tunnel endpoint identifier into the corresponding Interwork
   type routing instance.

7.  Illustration

   This section shows an illustration of SRv6 MUP deployment.  The
   example deployment cases here is 3GPP 5G.

   Before enabling SRv6 MUP, how SRv6 networks can accommodate existing
   mobile network service shown in Figure 2.  SR nodes S1, S2, and S3
   join an SR network.  A routing instance is configured to each network
   of the mobile service.  N6DN in S1 and S2 are supposed to provide
   connectivity to edge servers and the Internet respectively.

   VRF (Virtual Routing Forwarding) may be a way to instantiate the
   routing instance for realizing the routing policy of each instance.
   All example cases in this section follow the typical routing policy
   control using the BGP extended community described in [RFC4360] and
   [RFC4684]









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             __ N3   /-----------+-----+------------\
            /  \RAN /            |MUP-C|             \
           / V/v\_  |            +-----+             | N6   __
           \    / \ |----+                      +----| DN  /  \
            \__/   \| S1 |                      | S2 |----/W/w \
             __    /|----+                      +----|    \    /
            /  \__/ |             +----+             |     \__/
           / E/e\N6 \             | S3 |             /
           \    /DN  \------------+----+------------/
            \__/             N3UPF  /\ N6UPF
                               X/x /  \ Y/y
                                 +-----+
                                 | UPF |
                                 +-----+

                                  Figure 2

   The following routing instances are configured:

   *  N3RAN in S1

      -  export route V/v with route-target (RT) community C1

      -  import routes which have route-target (RT) community C1 and C2

   *  N6DN in S1

      -  export route E/e with RT C4

      -  import routes which have RT C3 and C4

   *  N6DN in S2

      -  export route W/w with RT C4

      -  import routes which have RT C3 and C4

   *  N3UPF in S3

      -  export route X/x with RT C2

      -  import routes which have RT C1

   *  N6UPF in S3

      -  export route Y/y with RT C3

      -  import routes which have RT C4



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   Note:  The above configurations are just to provide typical IP
         connectivity for 3GPP 5G.  When the above configurations have
         been done, each endpoint in V/v and X/x can communicate through
         S1 and S3, but they can not communicate with nodes in E/e, W/w
         and Y/y.

   Here, SR nodes are configured to enable SRv6 MUP as following:

   *  S1 as MUP GW

      -  advertises Interwork type discovery route: V/v with SID S1::

      -  set S1:: behavior End.M.GTP4.E or End.M.GTP6.E

   *  S1 as MUP PE

      -  advertise Direct type discovery route: MUP direct segment
         community D1 and SID S1:1::

      -  set S1:1:: behavior End.DT4 or End.DT6 for the N6DN in S1

   *  S2 as MUP PE

      -  advertise Direct type route: MUP direct segment community D1
         and SID S2::

      -  set S2:: behavior End.DT4 or End.DT6 for the N6DN in S2

   S1 here adopts the local N6DN for D1 as long as S1 prioritizes closer
   segment for the same MUP direct segment.  Another MUP GW runs on a SR
   node may adopt D1 from S2, if the SR node has no local N6DN for D1
   and closer to S2 than S1.



















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                                   U1
                                    |
          U/u                       v
            \__ N3   /-----------+-----+------------\
            /  \RAN /            |MUP-C|             \
           / V/v\_  |            +-----+             | N6   __
           \    / \ |----+                      +----| DN  /  \
            \__/   \| S1 |                      | S2 |----/W/w \
             __    /|----+                      +----|    \    /
            /  \__/ |             +----+             |     \__/
           / E/e\N6 \             | S3 |             /
           \    /DN  \------------+----+------------/
            \__/             N3UPF  /\ N6UPF
                               X/x /  \ Y/y
                                 +-----+
                                 | UPF |
                                 +-----+

                                  Figure 3

   Now, session information U1 comes to a MUP Controller, MUP-C, and
   MUP-C is configured to transforms U1 to the routes as follows:

   *  MUP-C

      -  attach the RT C3 to the DN in U1

      -  transforms UE's prefix U/u, the F-TEID on access side (gNB) and
         QFI in U1 to the Type 1 session transformed route for the
         prefix U/u with the F-TEID, the QFI, and RT C3

      -  transforms F-TEID on core side (UPF) X in U1 to the Type 2
         session transformed route for X with MUP segment-ID D1 and RT
         C2

   Then N3RAN and N6DN import route X and U/u respectively.  S1 and S2
   resolves U/u's remote endpoint with V/v and then install SID S1:: for
   U/u in FIB.  S1:: will not be appeared in the packet from E/e to U/u
   over the wire.

   As S1 adopts local N6DN for D1, N3RAN in S1 decapsulates GTP-U
   packets from V/v to X and then lookup the inner packets from U/u in
   N6DN after the decapsulation.

   Note:  When the above configurations have been done, SRv6 MUP is






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         applied only to the packets from/to U/u.  Each endpoint in U/u,
         W/w and E/e can communicate through S1 and S2.  The rest of
         traffic from/to other UEs go through the usual 3GPP 5G user
         plane path using UPF via S3.

   Another case shown in Figure 4 is that S4 joins the SR network and
   accommodates edge servers in the N6DN in S4.

                                   U1
                                    |
          U/u                       v                       __
            \__ N3   /-----------+-----+------------\      /  \
            /  \RAN /            |MUP-C|             \  __/W/w \
           / V/v\_  |            +-----+        +----|_/N6\    /
           \    / \ |----+                      | S2 |  DN \__/
            \__/   \| S1 |                      +----|      __
             __    /|----+                      +----|_    /  \
            /  \__/ |             +----+        | S4 | \__/E/e \
           /    \N6 \             | S3 |        +----/  N6\    /
           \    /DN  \------------+----+------------/   DN \__/
            \__/             N3UPF  /\ N6UPF
                               X/x /  \ Y/y
                                 +-----+
                                 | UPF |
                                 +-----+

                                  Figure 4

   The following routing instances are configured:

   *  N3RAN in S1 (same with the previous case)

      -  export route V/v with RT C1

      -  import routes which have RT C1 and C2

   *  N6DN in S1

      -  export no route

      -  import routes which have RT C4

   *  N6DN in S2 (same with the previous case)

      -  export route W/w with RT C4

      -  import routes which have RT C3 and C4




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   *  N3UPF in S3 (same with the previous case)

      -  export route X/x with RT C2

      -  import routes which have RT C1

   *  N6UPF in S3 (same with the previous case)

      -  export route Y/y with RT C3

      -  import routes which have RT C4

   *  N6DN in S4

      -  export route E/e with RT C4

      -  import routes which have RT C3 and C4

   Here, SR nodes are configured to enable SRv6 MUP as following:

   *  S1 as MUP GW (same with the previous case)

      -  advertises Interwork type route: V/v with SID S1::

      -  set S1:: behavior End.M.GTP4.E or End.M.GTP6.E

   *  S1 as MUP PE

      -  advertise Direct type route: MUP direct segment community D1
         for the local N6DN

      -  set S1:1:: behavior End.DT4 or End.DT6 for the N6DN in S1

   *  S2 as MUP PE (same with the previous case)

      -  advertise Direct type route: MUP direct segment community D1
         and SID S2::

      -  set S2:: behavior End.DT4 or End.DT6 for the N6DN in S2

   *  S4 as MUP PE

      -  advertise Direct type route: MUP direct segment community D2
         and SID S4::

      -  set S4:: behavior End.DT4 or End.DT6 for the N6DN in S4





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   As same as the previous case, S1 adopts the local N6DN for D1 as long
   as S1 prioritizes closer segment for the same MUP direct segment.
   The Direct type route from S4 for D2 with SID S4:: will be kept in
   S1.

   *  MUP-C (same with the previous case)

      -  attach the RT C3 to the DN in U1

      -  transforms UE's prefix U/u, the F-TEID on access side (gNB) and
         QFI in U1 to the Type 1 session transformed route for the
         prefix U/u with the F-TEID, the QFI, and RT C3

      -  transforms F-TEID on core side (UPF) X in U1 to the Type 2
         session transformed route for X with MUP direct segment
         community D1 and RT C2

   Then N3RAN and N6DN import route X and U/u respectively.  S2 and S4
   resolve U/u's remote endpoint with V/v and then install SID S1:: for
   U/u in FIB.

   As same as the previous case, S1 adopts local N6DN for D1, N3RAN in
   S1 decapsulates GTP-U packets from V/v to X and then lookup the inner
   packets from U/u in N6DN after the decapsulation.

   For D2 on the other hand, no corresponding N6DN existed in S1.
   However E/e with RT C4 from S4 is imported into N6DN in S1 as a vpn
   route, E/e is reachable from U/u via N6DN for D1 in S1.

   If a session U1' includes DN corresponding to D2, MUP-C advertises
   Type 2 session transformed route X' with MUP direct segment community
   D2, and then N3RAN in S1 instantiates H.M.GTP4.D or End.M.GTP6.D for
   X with S4:: as the last SID in the received Direct type route from
   S4.

   Note:  When the above configurations have been done, SRv6 MUP is
         applied only to the packets from/to U/u.  Each endpoint in U/u,
         W/w and E/e can communicate through S1, S2 and S4.  The rest of
         traffic from/to other UEs go through the usual 3GPP 5G user
         plane path using UPF via S3.

8.  IANA Considerations

   This memo includes no request to IANA.







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9.  Security Considerations

   TBD.

10.  References

10.1.  Normative References

   [I-D.ietf-dmm-srv6-mobile-uplane]
              Matsushima, S., Filsfils, C., Kohno, M., Garvia, P. C.,
              Voyer, D., and C. E. Perkins, "Segment Routing IPv6 for
              Mobile User Plane", Work in Progress, Internet-Draft,
              draft-ietf-dmm-srv6-mobile-uplane-18, 18 February 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-dmm-
              srv6-mobile-uplane-18>.

   [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>.

   [RFC7333]  Chan, H., Ed., Liu, D., Seite, P., Yokota, H., and J.
              Korhonen, "Requirements for Distributed Mobility
              Management", RFC 7333, DOI 10.17487/RFC7333, August 2014,
              <https://www.rfc-editor.org/info/rfc7333>.

   [RFC8402]  Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
              Decraene, B., Litkowski, S., and R. Shakir, "Segment
              Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
              July 2018, <https://www.rfc-editor.org/info/rfc8402>.

   [RFC8986]  Filsfils, C., Ed., Camarillo, P., Ed., Leddy, J., Voyer,
              D., Matsushima, S., and Z. Li, "Segment Routing over IPv6
              (SRv6) Network Programming", RFC 8986,
              DOI 10.17487/RFC8986, February 2021,
              <https://www.rfc-editor.org/info/rfc8986>.

10.2.  Informative References

   [RFC4360]  Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
              Communities Attribute", RFC 4360, DOI 10.17487/RFC4360,
              February 2006, <https://www.rfc-editor.org/info/rfc4360>.









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   [RFC4684]  Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk,
              R., Patel, K., and J. Guichard, "Constrained Route
              Distribution for Border Gateway Protocol/MultiProtocol
              Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual
              Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684,
              November 2006, <https://www.rfc-editor.org/info/rfc4684>.

   [RFC5213]  Gundavelli, S., Ed., Leung, K., Devarapalli, V.,
              Chowdhury, K., and B. Patil, "Proxy Mobile IPv6",
              RFC 5213, DOI 10.17487/RFC5213, August 2008,
              <https://www.rfc-editor.org/info/rfc5213>.

   [RFC8885]  Bernardos, CJ., de la Oliva, A., Giust, F., Zúñiga, JC.,
              and A. Mourad, "Proxy Mobile IPv6 Extensions for
              Distributed Mobility Management", RFC 8885,
              DOI 10.17487/RFC8885, October 2020,
              <https://www.rfc-editor.org/info/rfc8885>.

   [TS.23501] 3GPP, "System architecture for the 5G System (5GS)", 3GPP
              TS 23.501 17.2.0, 24 September 2021,
              <http://www.3gpp.org/ftp/Specs/html-info/23501.htm>.

Authors' Addresses

   Satoru Matsushima
   SoftBank
   Japan
   Email: satoru.matsushima@g.softbank.co.jp


   Katsuhiro Horiba
   SoftBank
   Japan
   Email: katsuhiro.horiba@g.softbank.co.jp


   Ashiq Khan
   SoftBank
   Japan
   Email: ashiq.khan@g.softbank.co.jp


   Yuya Kawakami
   SoftBank
   Japan
   Email: yuya.kawakami01@g.softbank.co.jp





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   Tetsuya Murakami
   Arrcus, Inc.
   United States of America
   Email: tetsuya@arrcus.com


   Keyur Patel
   Arrcus, Inc.
   United States of America
   Email: keyur@arrcus.com


   Miya Kohno
   Cisco Systems, Inc.
   Japan
   Email: mkohno@cisco.com


   Teppei Kamata
   Cisco Systems, Inc.
   Japan
   Email: tkamata@cisco.com


   Pablo Camarillo Garvia
   Cisco Systems, Inc.
   Spain
   Email: pcamaril@cisco.com


   Daniel Voyer
   Bell Canada
   Canada
   Email: daniel.voyer@bell.ca


   Shay Zadok
   Broadcom
   Israel
   Email: shay.zadok@broadcom.com


   Israel Meilik
   Broadcom
   Israel
   Email: israel.meilik@broadcom.com





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   Ashutosh Agrawal
   Intel
   United States of America
   Email: ashutosh.agrawal@intel.com


   Kumaresh Perumal
   Intel
   United States of America
   Email: kumaresh.perumal@intel.com


   Jakub Horn
   Cisco Systems, Inc.
   Czech Republic
   Email: jakuhorn@cisco.com



































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