INTAREA                                                      S. Kanugovi
Internet-Draft                                              S. Vasudevan
Intended status: Standards Track                                   Nokia
Expires: September 28, 2017                                       J. Zhu
                                                                   Intel
                                                             F. Baboescu
                                                                Broadcom
                                                                 S. Peng
                                                                  Huawei
                                                                  S. Seo
                                                           Korea Telecom
                                                          March 27, 2017


 Control Plane Protocols and Procedures for Multiple Access Management
                                Services
               draft-zhu-intarea-mams-control-protocol-01

Abstract

   Today, a device can be simultaneously connected to multiple
   communication networks based on different technology implementations
   and network architectures like WiFi, LTE, DSL.  In such multi-
   connectivity scenario, it is desirable to combine multiple access
   networks or select the best one to improve quality of experience for
   a user and improve overall network utilization and efficiency.  This
   document presents the control plane protocols, as well as describes
   control plane procedures for configuring the user plane in a multi
   access management services (MAMS) framework that can be used to
   flexibly select the combination of uplink and downlink access and
   core network paths, and user plane treatment for improving network
   efficiency and enhanced application quality of experience.

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 http://datatracker.ietf.org/drafts/current/.

   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."




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   This Internet-Draft will expire on September 28, 2017.

Copyright Notice

   Copyright (c) 2017 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
   (http://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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   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.  Conventions used in this document . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  MAMS Control-Plane Protocol . . . . . . . . . . . . . . . . .   3
     4.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   3
   5.  MAMS User Plane Protocol  . . . . . . . . . . . . . . . . . .   4
   6.  MAMS Control Plane Procedures . . . . . . . . . . . . . . . .   6
     6.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . .   6
     6.2.  Common fields in MAMS Control Messages  . . . . . . . . .   7
     6.3.  Discovery & Capability Exchange . . . . . . . . . . . . .   7
     6.4.  User Plane Configuration  . . . . . . . . . . . . . . . .  10
     6.5.  MAMS Path Quality Estimation  . . . . . . . . . . . . . .  12
     6.6.  MAMS Traffic Steering . . . . . . . . . . . . . . . . . .  13
   7.  Applying MAMS Control Procedures with MPTCP Proxy as User
       Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   8.  Co-existence of MX Adaptation and MX Convergence Layers . . .  16
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
     9.1.  MAMS Control plane security . . . . . . . . . . . . . . .  16
     9.2.  MAMS User plane security  . . . . . . . . . . . . . . . .  16
   10. Contributing Authors  . . . . . . . . . . . . . . . . . . . .  16
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     11.2.  Informative References . . . . . . . . . . . . . . . . .  17
   Appendix A.  MAMS Control Plane Optimization over Secure
                Connections  . . . . . . . . . . . . . . . . . . . .  18
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  18






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1.  Conventions used in this document

   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 [RFC2119].

2.  Introduction

   Multi Access Management Service (MAMS)
   [I-D.kanugovi-intarea-mams-protocol] is a framework to select and
   configure network paths when multiple connections can serve a client
   device.  It allows the path selection and configuration to adapt to
   dynamic network conditions.  It is based on principles of user plane
   interworking that enables the solution to be deployed as an overlay
   without impacting the underlying networks.

   This document presents the control plane protocols for the MAMS
   framework.  It co-exists and complements user plane protocols (e.g.
   MPTCP [RFC6824] or MPTCP Proxy [I-D.boucadair-mptcp-plain-mode],
   [I-D.wei-mptcp-proxy-mechanism]) by providing a way to negotiate and
   configure them based on client and network capabilities.  It allows
   exchange of network state information and leverages network
   intelligence to optimize the performance of such protocols.

3.  Terminology

   "Anchor Connection": Refers to the network path from the N-MADP to
   the Application Server that corresponds to a specific IP anchor that
   has assigned an IP address to the client.

   "Delivery Connection": Refers to the network path from the N-MADP to
   the client.

   "Network Connection Manager" (NCM), "Client Connection Manager"
   (CCM), "Network Multi Access Data Proxy" (N-MADP), and "Client Multi
   Access Data Proxy" (C-MADP) in this document are to be interpreted as
   described in [I-D.kanugovi-intarea-mams-protocol].

4.  MAMS Control-Plane Protocol

4.1.  Overview

   The MAMS architecture [I-D.kanugovi-intarea-mams-protocol] introduces
   the following functional elements,

   o  Network Connection Manager (NCM) and Client Connection Manager
      (CCM) in the control plane, and




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   o  Network Multi Access Data Proxy (N-MADP) and Client Multi Access
      Data Proxy (C-MADP) handling the user plane.

   Figure 1 shows the default MAMS control plane protocol stack.  HTTPS
   is used for transporting management and control messages between NCM
   and CCM.



                 +------------------------------------------+
                 |    Multi Access (MX) Control Message     |
                 |                                          |
                 +------------------------------------------+
                 |                HTTPS                     |
                 |                                          |
                 +------------------------------------------+
                 |               TCP/TLS                    |
                 |                                          |
                 +------------------------------------------+


           Figure 1: TCP-based MAMS Control Plane Protocol Stack

5.  MAMS User Plane Protocol

   Figure 2 shows the MAMS user plane protocol stack.

























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          +-----------------------------------------------------+
          |      User Payload (e.g. IP PDU)                     |
          +-----------------------------------------------------+

       +-----------------------------------------------------------+
       |  +-----------------------------------------------------+  |
       |  | Multi Access (MX) Convergence Sublayer              |  |
       |  +-----------------------------------------------------+  |
       |  +-----------------------------------------------------+  |
       |  | MX Adaptation   | MX Adaptation  | MX Adaptation    |  |
       |  | Sublayer        | Sublayer       | Sublayer         |  |
       |  | (optional)      | (optional)     | (optional)       |  |
       |  +----------------++--------------+-+------------------+  |
       |  | Access #1 IP   | Access #2 IP  | Access #3 IP       |  |
       |  +-----------------------------------------------------+  |
       |                             MAMS User Plane Protocol Stack|
       +-----------------------------------------------------------+




                 Figure 2: MAMS User Plane Protocol Stack

   It consists of the following two Sublayers:

   o  Multi-Access (MX) Convergence Sublayer: This layer performs multi-
      access specific tasks, e.g. access (path) selection, multi-link
      (path) aggregation, splitting/reordering, lossless switching,
      fragmentation, concatenation, etc.  For example, MX Convergence
      layer can be implemented using existing user plane protocols like
      MPTCP or by adapting encapsulating header/trailer schemes (e.g
      Trailer Based MX Convergence as specified in
      [I-D.zhu-intarea-mams-user-protocol]).
   o  Multi-Access (MX) Adaptation Sublayer: This layer performs
      functions to handle tunnelling, network layer security, and NAT.
      For example, MX Adaptation can be implemented using IPsec, DTLS or
      Client NAT (Source NAT at Client with inverse mapping at N-MADP
      [I-D.zhu-intarea-mams-user-protocol] ).  The MX Adaptation Layer
      is optional and can be independently configured for each of the
      Access Links, e.g. in a deployment with LTE (assumed secure) and
      Wi-Fi (assumed not secure), the MX Adaptation Sublayer can be
      omitted for the LTE link but MX Adaptation Sublayer is configured
      as IPsec for the Wi-Fi link.








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6.  MAMS Control Plane Procedures

6.1.  Overview

   CCM and NCM exchange signaling messages to configure the user plane
   functions, C-MADP and N-MADP, at the client and network respectively.
   The means for CCM to obtain the NCM credentials (FQDN or IP Address)
   for sending the initial discovery messages are outside of the scope
   of MAMS document, e.g. using methods like provisioning, DNS.  Once
   the discovery process is successful, the (initial) NCM can update and
   assign additional NCM addresses for sending subsequent control plane
   messages.

   CCM discovers and exchanges capabilities with the NCM.  NCM provides
   the credentials of the N-MADP end-point and negotiates the parameters
   for user plane with the CCM.  CCM configures C-MADP to setup the user
   plane path (e.g.  MPTCP/UDP Proxy Connection) with the N-MADP based
   on the credentials (e.g.  (MPTCP/UDP) Proxy IP address and port,
   Associated Core Network Path), and the parameters exchanged with the
   NCM.  The key procedures are described in details in the following
   sub-sections.






























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                      +-----+                +-----+
                      | CCM |                | NCM |
                      +--+--+                +--+--+
                         |    Discovery and     |
                         |    Capability        |
                         |    Exchange          |
                         <---------------------->
                         |                      |
                         |    User Plane        |
                         |    Protocols         |
                         |    Setup             |
                         <---------------------->
                         |    Path Quality      |
                         |    Estimation        |
                         <---------------------->
                         | Network capabilities |
                         | e.g. Radio (RNIS)    |
                         <----------------------+
                         |                      |
                         | Network policies     |
                         <----------------------+
                         +                      +





                  Figure 3: MAMS Control Plane Procedures

6.2.  Common fields in MAMS Control Messages

   Each MAMS control message consists of the following common fields:

   o  Version: indicates the version of MAMS control protocol.
   o  Message Type: indicates the type of the message, e.g.  MX
      Discovery, MX Capability REQ/RSP etc.
   o  Sequence Number: auto-incremented integer to uniquely identify a
      transaction of message exchange, e.g.  MX Capability REQ/RSP.

6.3.  Discovery & Capability Exchange

   Figure 4 shows the MAMS discovery and capability exchange procedure
   consisting of the following key steps:








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         CCM                                                  NCM
          |                                                    |
          +------- MX Discovery Message ---------------------->|
          |                                         +-----------------+
          |                                         |Learn CCM        |
          |                                         | IP address      |
          |                                         |& port           |
          |                                         +-----------------+
          |                                                    |
          |<--------------------------------MX System INFO-----|
          |                                                    |
          |<--------------------------------MX Capability REQ--|
          |------ MX Capability RSP+-------------------------->|
          |                                                    |
          +                                                    +


   Figure 4: MAMS Control Procedure for Discovery & Capability Exchange

   Step 1 (Discovery): CCM periodically sends out the MX Discovery
   Message to a pre-defined (NCM) IP Address/ port until receives an MX
   System INFO message in acknowledgement.

   MX Discovery Message includes the following information:

   o  MAMS Version

   MX System INFO includes the following information:

   o  Number of Anchor Connections

      For each Anchor Connection, it includes the following parameters:

      *  Connection ID: Unique identifier for the Anchor Connection
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NR; 2: Multi-Fire; 3:
         LTE)
      *  NCM Endpoint Address (For Control Plane Messages over this
         connection)

         +  IP Address or FQDN (Fully Qualified Domain Name)
         +  Port Number

   Step 2 (Capability Exchange): once receiving a MX discovery message,
   NCM learns the IP address and port number to communicate with CCM,
   and sends out the MX Capability REQ message, including the following
   Parameters:





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   o  MX Feature Activation List: Indicates if the corresponding feature
      is enabled or not, e.g. lossless switching, fragmentation,
      concatenation, Uplink aggregation, Downlink aggregation,
      Measurement, etc.
   o  Number of Anchor Connections (Core Networks)

      For each Anchor Connection, it includes the following parameters:

      *  Connection ID
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NR; 2: Multi-Fire; 3:
         LTE)
   o  Number of Delivery Connections (Access Links)

      For each Delivery Connection, it includes the following
      parameters:

      *  Connection ID
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NR; 2: Multi-Fire; 3:
         LTE)
   o  MX Convergence Method Support List

      *  Trailer-based MX Convergence;
      *  MPTCP Proxy;
   o  MX Adaptation Method Support List

      *  UDP Tunnel without DTLS;
      *  UDP Tunnel with DTLS;
      *  IPsec Tunnel[RFC3948];
      *  Client NAT;

   In response, CCM sends out the MX Capability RSP message, including
   the following information:

   o  MX Feature Activation List: Indicates if the corresponding feature
      is enabled or not, e.g. lossless switching, fragmentation,
      concatenation, Uplink aggregation, Downlink aggregation,
      Measurement, etc.
   o  Number of Anchor Connections (Core Networks)

      For each Anchor Connection, it includes the following parameters:

      *  Connection ID
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NR; 2: Multi-Fire; 3:
         LTE)
   o  Number of Delivery Connections (Access Links)

      For each Delivery Connection, it includes the following
      parameters:



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      *  Connection ID
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NR; 2: Multi-Fire; 3:
         LTE)
   o  MX Convergence Method Support List

      *  Trailer-based MX Convergence;
      *  MPTCP Proxy;
   o  MX Adaptation Method Support List

      *  UDP Tunnel without DTLS;
      *  UDP Tunnel with DTLS;
      *  IPsec Tunnel[RFC3948];
      *  Client NAT;

6.4.  User Plane Configuration

   Figure 5 shows the user plane configuration procedure consisting of
   the following key steps:


CCM                                                   NCM
 |                                                    |
 |                                        +-----------+----------------+
 |                                        | NCM prepares N+MADP for    |
 |                                        | User Plane|Setup           |
 |                                        +----------------------------+
 |<----------------------------- MX UP Setup Config---|
 |-----| MX UP Setup CNF+---------------------------->|
+-------------------+                                 |
|Link "X" is up/down|                                 |
+-------------------+                                 |
 |-----|MX Reconfiguration REQ +--------------------->|
 |<------------------------+MX Reconfiguration RSP+---|




       Figure 5: MAMS Control Procedure for User Plane Configuration

   User Plane Protocols Setup: Based on the negotiated capabilities, NCM
   sets up the user plane (Adaptation Layer and Convergence Layer)
   protocols at the N-MADP, and informs the CCM of the user plane
   protocols to setup at the client (C-MADP) and the parameters for
   C-MADP to connect to N-MADP.

   Each MADP instance is responsible for one anchor connection.  The MX
   UP Setup Config consists of the following parameters:




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   o  Number of Anchor Connections (Core Networks)

      For Each Anchor Connection, it includes the following parameters

      *  Anchor Connection ID
      *  Connection Type (e.g., 0: Wi-Fi; 1: 5G NGC; 2: Multi-Fire; 3:
         LTE)
      *  MX Convergence Method

         +  Trailer-based MX Convergence;
         +  MPTCP Proxy;
      *  MX Convergence Method Parameters

         +  Convergence Proxy IP Address
         +  Convergence Proxy Port
      *  Number of Delivery Connections

         For each Delivery Connection, include the following:

         +  Delivery Connection ID
         +  Connection Type (e.g., 0: Wi-Fi; 1: 5G NGC; 2: Multi-Fire;
            3: LTE)
         +  MX Adaptation Method

            -  UDP Tunnel without DTLS;
            -  UDP Tunnel with DTLS;
            -  IPSec Tunnel;
            -  Client NAT;
         +  MX Adaptation Method Parameters

            -  Tunnel Endpoint IP Address
            -  Tunnel Endpoint Port
            -  Shared Secret

   e.g.  When LTE and Wi-Fi are the two user plane accesses, NCM conveys
   to CCM that IPsec needs to be setup as the MX Adaptation Layer over
   the Wi-Fi Access, using the following parameters - IPsec end-point IP
   address, Pre-Shared Key., No Adaptation Layer is needed over the LTE
   Access as it is considered secure with no NAT.  The MX Convergence
   Method is configured as MPTCP Proxy along with parameters for
   connection to the MPTCP Proxy, namely IP Address and Port of the
   MPTCP Proxy for TCP Applications.

   Once the user plane protocols are configured, CCM informs the NCM of
   the status via the MX UP Setup CNF message

   Reconfiguration: when the client detects that the link is up/down or
   the IP address changes (e.g. via APIs provided by the client OS), CCM



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   sends out a MX Reconfiguration REQ Message to setup / release /update
   the connection, and the message SHOULD include the following
   information

   o  Reconfiguration Action: indicate the reconfiguration action (0:
      release; 1: setup; 2: update)
   o  Connection ID: identify the connection for reconfiguration

   If (Reconfiguration Action is setup or update), then include the
   following parameters

   o  IP address of the connection
   o  MTU (Maximum Transmission Unit) size of the connection

6.5.  MAMS Path Quality Estimation


          CCM                                                 NCM
          |                                                    |
          |<--------------+ MX Path Estimation Configuration+--|
          |-----+ MX Path Estimation Results+----------------->|
          |                                                    |





    Figure 6: MAMS Control Plane Procedure for Path Quality Estimation

   NCM sends following the configuration parameters in the MX Path
   Estimation Configuration message to the CCM

   o  Connection ID (of Delivery Connection whose path quality needs to
      be estimated)
   o  Init Probe Test Duration (ms)
   o  Init Probe Test Rate (Mbps)
   o  Init Probe Size (Bytes)
   o  Init Probe Ack Required (0 -> No/1 -> Yes)
   o  Active Probe Frequency (ms)
   o  Active Probe Size (Bytes)
   o  Active Probe Ack Required (0 -> No/1 -> Yes)

   CCM configures the C-MADP for probe reception based on these
   parameters and for collection of the statistics according to the
   following configuration.

   o  Init Probe Results Configuration




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      *  Lost Probes (%)
      *  Probe Delay
      *  Probe Rate
   o  Active Probe Results Configuration

      *  Average Throughput in the last Probe Duration

   The user plane probing is divided into two phases - Initialization
   phase and Active phase.

   o  Initialization phase: A network path that is not included by
      N-MADP for transmission of user data is deemed to be in the
      Initialization phase.  The user data may be transmitted over other
      available network paths.
   o  Active phase: A network path that is included by N-MADP for
      transmission of user data is deemed to be in Active phase.

   In Initialization phase, NCM configures N-MADP to send an MX Idle
   Probe REQ message.  CCM collects the Idle probe statistics from
   C-MADP and sends the MX Path Estimation Results Message to NCM per
   the Initialization Probe Results configuration.

   In Active phase, NCM configures N-MADP to send an MX Active Probe REQ
   message..  C-MADP calculates the metrics as specified by the Active
   Probe Results Configuration.  CCM collects the Active probe
   statistics from C-MADP and sends the MX Path Estimation Results
   Message to NCM per the Active Probe Results configuration.

6.6.  MAMS Traffic Steering


    CCM                                               NCM
     |                                                 |
     |                                +------------------------------+
     |                                |Steer user traffic to Path "X"|
     |                                +------------------------------+
     |<------------------MX Traffic Steering (TS) REQ--|
     |----- MX Traffic Steering (TS) RSP ------------->|


                 Figure 7: MAMS Traffic Steering Procedure

   NCM sends out a MX Traffic Steering (TS) REQ message to steer data
   traffic.  It is also possible to send data traffic over multiple
   connections simultaneously, i.e. aggregation.  The message includes
   the following information:

   o  Connection ID of the Anchor Connection



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   o  Connection ID List of Delivery Connections for DL traffic
   o  Connection ID List of Delivery connections for UL traffic
   o  MX Feature Activation List: each parameter indicates if the
      corresponding feature is enabled or not: lossless switching,
      fragmentation, concatenation, Uplink aggregation, Downlink
      aggregation, Measurement

   In response, CCM sends out a MX Traffic Steering (TS) RSP message,
   including the following information:

   o  MX Feature Activation List: each parameter indicates if the
      corresponding feature is enabled or not: lossless switching,
      fragmentation, concatenation, Uplink aggregation, Downlink
      aggregation

7.  Applying MAMS Control Procedures with MPTCP Proxy as User Plane

   If NCM determines that N-MADP is to be instantiated with MPTCP as the
   MX Convergence Protocol, it exchanges the MPTCP capability support in
   discovery and capability exchange procedures.  NCM then exchanges the
   credentials of the N-MADP instance, setup as MPTCP Proxy, along with
   related parameters to the CCM.  CCM configures C-MADP with these
   parameters to connect with the N-MADP (MPTCP proxy
   [I-D.wei-mptcp-proxy-mechanism], [I-D.boucadair-mptcp-plain-mode])
   instance, on the available network path (Access).

   Figure 8 shows the MAMS assisted MPTCP Proxy control procedure.

   o  For securing the TCP subflow data over links that cannot be
      assumed to be secure, NCM configures MX Adaptation Layer.  E.g.
      NCM can inform CCM to use IPsec as the MX Adaptation Layer over
      the link "X" (e.g.  Wi-Fi).  CCM informs C-MADP to set up IPSec
      (transport mode) with N-MADP using the MPTCP-Proxy IP address to
      protect the TCP subflow over Link "X".
   o  NCM informs the CCM that N-MADP is configured as the MPTCP proxy
      and provides the parameters like MPTCP Proxy IP address/Port.
      C-MADP obtains the IP address & port of MPTCP-Proxy for Link "X"
      locally from CCM.  This is useful if N-MADP is reachable via
      different IP address or/and port, from different access networks.
      The current MPTCP signaling can't identify or differentiate the
      MPTCP proxy IP address & port among multiple access networks.










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    C-MADP                      N-MADP                        Internet
    (MPTCP)                     (MPTCP-Proxy)                 (TCP)
      |                              |                          |
    +---------------+                |                          |
    |Link "X" is up |                |                          |
    +---------------+                |                          |
      |                              |                          |
    +---------------------+          |                          |
    |obtain MX Adaptation |          |                          |
    |Layer (IPsec) Params |          |                          |
    +---------------------+          |                          |
      |<-- IKEv2 Message Exchange--->|                          |
    +-------------------------------------------+               |
    |  IPSec transport mode is active to protect|               |
    |  IP traffic between C-MADP and MPTCP-Proxy|               |
    +-------------------------------------------+               |
      |                              |                          |
    +------------------+             |                          |
    |obtain MPTCP-Proxy|             |                          |
    |IP address of Link|             |                          |
    |"X" from CCM      |             |                          |
    +------------------+             |                          |
      |                              |                          |
    +--------------------------------|--+                       |
    |  MPTCP Signaling between       |  |                       |
    |  C-MADP and MPTCP-Proxy        |  |                       |
    +--------------------------------|--+                       |
      |                           +---------+                   |
      |                           | inspect |                   |
      |                           | MPTCP   |                   |
      |                           | signal  |                   |
      |                           |  and    |                   |
      |                           |establish|                   |
      |                           |sub-flow |                   |
      |                           | over    |                   |
      |                           | Link "X"|                   |
      |                           +--|------+                   |
      |                       +------------+                    |
      |<======Data===========>|Data Mapping|<----Data---------->|
      |                       +------|-----+                    |




             Figure 8: MAMS-assisted MPTCP Proxy as User Plane






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8.  Co-existence of MX Adaptation and MX Convergence Layers

   MAMS u-plane protocols support multiple combinations and instances of
   user plane protocols to be used in the MX Adaptation and the
   Convergence layer.

   For example, one instance of the MX Convergence Layer can be MPTCP
   Proxy and another instance can be Trailer based.  The MX Adaptation
   for each can be either UDP tunnel or IPsec.  IPSec may be set up when
   network pathneeds to be secured, e.g. to protect the TCP subflow
   traversing the network path between the client and MPTCP proxy.

   Each of the instances of MAMS user plane, i.e. combination of MX
   Convergence and MX Adaptation layer protocols, can coexist
   simultaneously and independently handle different traffic types.

9.  Security Considerations

9.1.  MAMS Control plane security

   For deployment scenarios, where the client is configured (e.g. by the
   network operator) to use a specific network for exchanging control
   plane messages and assume the network path to be secure, MAMS control
   messages will rely on security provided by the underlying transport
   network.

   For deployment scenarios where the security of the network path
   cannot be assumed, NCM and CCM implementations MUST support the
   "https" URI scheme [RFC2818] and Transport Layer Security (TLS)
   [RFC5246] to secure control plane message exchange between the NCM
   and CCM.

   For deployment scenarios where client authentication is desired, HTTP
   Digest Authentication MUST be supported.  TLS Client Authentication
   is the preferred mechanism if it is available.

9.2.  MAMS User plane security

   User data in MAMS framework relies on the security of the underlying
   network transport paths.  When this cannot be assumed, NCM configures
   use of protocols, like IPsec [RFC4301] [RFC3948] in the MX Adaptation
   Layer, for security.

10.  Contributing Authors

   The editors gratefully acknowledge the following additional
   contributors in alphabetical order: A Krishna Pramod/Nokia, Hannu
   Flinck/Nokia, Hema Pentakota/Nokia, Nurit Sprecher/Nokia



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11.  References

11.1.  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,
              <http://www.rfc-editor.org/info/rfc2119>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <http://www.rfc-editor.org/info/rfc4301>.

11.2.  Informative References

   [I-D.boucadair-mptcp-plain-mode]
              Boucadair, M., Jacquenet, C., Bonaventure, O., Behaghel,
              D., stefano.secci@lip6.fr, s., Henderickx, W., Skog, R.,
              Vinapamula, S., Seo, S., Cloetens, W., Meyer, U.,
              Contreras, L., and B. Peirens, "Extensions for Network-
              Assisted MPTCP Deployment Models", draft-boucadair-mptcp-
              plain-mode-10 (work in progress), March 2017.

   [I-D.kanugovi-intarea-mams-protocol]
              Kanugovi, S., Vasudevan, S., Baboescu, F., Zhu, J., Peng,
              S., and J. Mueller, "Multiple Access Management Services",
              draft-kanugovi-intarea-mams-protocol-03 (work in
              progress), March 2017.

   [I-D.wei-mptcp-proxy-mechanism]
              Wei, X., Xiong, C., and E. Ed, "MPTCP proxy mechanisms",
              draft-wei-mptcp-proxy-mechanism-02 (work in progress),
              June 2015.

   [I-D.zhu-intarea-mams-user-protocol]
              Zhu, J., "User-Plane Protocols for Multiple Access
              Management Service", draft-zhu-intarea-mams-user-
              protocol-00 (work in progress), March 2017.

   [RFC3948]  Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
              Stenberg, "UDP Encapsulation of IPsec ESP Packets",
              RFC 3948, DOI 10.17487/RFC3948, January 2005,
              <http://www.rfc-editor.org/info/rfc3948>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <http://www.rfc-editor.org/info/rfc6347>.




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   [RFC6824]  Ford, A., Raiciu, C., Handley, M., and O. Bonaventure,
              "TCP Extensions for Multipath Operation with Multiple
              Addresses", RFC 6824, DOI 10.17487/RFC6824, January 2013,
              <http://www.rfc-editor.org/info/rfc6824>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <http://www.rfc-editor.org/info/rfc7296>.

Appendix A.  MAMS Control Plane Optimization over Secure Connections

   If the connection between CCM and NCM over which the MAMS control
   plane messages are transported is assumed to be secure, UDP is used
   as the transport for management & control messages between NCM and
   UCM (see Figure 9).



          +-----------------------------------------------------+
          |        Multi-Access (MX) Control Message            |
          |-----------------------------------------------------|
          |                UDP                                  |
          |-----------------------------------------------------|


           Figure 9: UDP-based MAMS Control plane Protocol Stack

Authors' Addresses

   Satish Kanugovi
   Nokia

   Email: satish.k@nokia.com


   Subramanian Vasudevan
   Nokia

   Email: vasu.vasudevan@nokia.com


   Jing Zhu
   Intel

   Email: jing.z.zhu@intel.com





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   Florin Baboescu
   Broadcom

   Email: florin.baboescu@broadcom.com


   Shuping Peng
   Huawei

   Email: pengshuping@huawei.com


   SungHoon Seo
   Korea Telecom

   Email: sh.seo@kt.com



































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