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INTAREA                                                          J. Zhu
Internet Draft                                                    Intel
Intended status: Standards Track                         March 13, 2017
Expires: September 14, 2017

        User-Plane Protocols for Multiple Access Management Service

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   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 u-plane protocols for a multi access
   management services (MAMS) framework that can be used to flexibly
   select the best combination of uplink and downlink access and core
   network paths, and user plane treatment for improving network
   efficiency and enhanced application quality of experience.

Table of Contents

   1. Introduction...................................................2
   2. Terminologies..................................................3
   3. Conventions used in this document..............................3
   4  MAMS User-Plane Protocols......................................3
      4.1   MX Adaptation Layer......................................4
      4.2   Trailer-based MX Convergence Layer.......................5
      4.3   MPTCP-based MX Convergence Layer.........................6
      4.4   Co-existence of MX Adaptation and MX Convergence Layers..6
   5  Security Considerations........................................6
   6  IANA Considerations............................................6
   7  Contributing Authors...........................................7
   8  References.....................................................7
      8.1   Normative References.....................................7
      8.2   Informative References...................................7

1. Introduction

   Multi Access Management Service (MAMS) [MAMS] is a programmable
   framework to select and configure network paths, as well as adapt to
   dynamic network conditions, when multiple network connections can
   serve a client device. 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 u-plane protocols for the MAMS framework.
   It co-exists and complements the existing protocols by providing a
   way to negotiate and configure the protocols based on client and
   network capabilities. Further it allows exchange of network state
   information and leveraging network intelligence to optimize the
   performance of such protocols. An important goal for MAMS is to
   ensure that there is minimal or no dependency on the actual access
   technology of the participating links. This allows the scheme to be

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   scalable for addition of newer accesses and for independent
   technology evolution of the existing accesses.

2. Terminologies

   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 [MAMS].

3. Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

   The terminologies "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 [MAMS].

4  MAMS User-Plane Protocols

Figure 1 shows the MAMS u-plane protocol stack as specified in
             |      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       |  |

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          |  +-----------------------------------------------------+  |
                 Figure 1: MAMS U-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.
o Multi-Access (MX) Adaptation Sublayer: This layer performs functions
  to handle tunnelling, network layer security, and NAT.

4.1  MX Adaptation Layer

The MX adaptation layer supports the following mechanisms and protocols
while transmitting user plane packets on the network path:

o UDP Tunneling: The user plane packets of the anchor connection can be
  encapsulated in a UDP tunnel of a delivery connection between the N-
  MADP and C-MADP.
o IPsec Tunneling: The user plane packets of the anchor connection are
  sent through an IPSec tunnel of a delivery connection.
o Client Net Address Translation (NAT): change the Client IP address of
  user plane packet of the anchor connection, and send it over a
  delivery connection.
o Pass Through: The user plane packets are passing through without any
  change over the anchor connection.

The MX adaptation layer also supports the following mechanisms and
protocols to ensure security of user plane packets over the network

o IPSec Tunneling: An IPsec [RFC7296] tunnel is established between the
  N-MADP and C-MADP on the network path that is considered untrusted.
o DTLS: If UDP tunneling is used on the network path that is considered
  "untrusted", DTLS (Datagram Transport Layer Security) [RFC6347] can
  be used.

The Client NAT method is most efficient due to no tunneling overhead.
It SHOULD be used if a delivery connection is "trusted" and without NAT
function on the path.

The UDP or IPSec Tunnelling method SHOULD be used if a delivery
connection has a NAT function on the path.

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4.2  Trailer-based MX Convergence Layer

Trailer based MX convergence integrates multiple connections into a
single e2e IP connection. It operates between Layer 2 (L2) and Layer 3

          <-------- MX PDU Payload ---------------->
          | IP (v4 or v6) header |  IP payload     | MX Trailer  |
           Figure 2: Trailer-based Multi-Access (MX) PDU Format

Figure 2 shows the trailer-based Multi-Access (MX) PDU (Protocol Data
Unit) format. A MX PDU MAY carry multiple IP PDUs in the payload if
concatenation is supported, and MAY carry a fragment of the IP PDU if
fragmentation is supported.

The MX trailer may consist of the following fields:

o Next Header (e.g. 1 byte): the IP protocol type of the (first) IP
  packet in a MX PDU
o Connection ID (e.g.1 byte): an unsigned integer to identify the
  anchor connection of the IP packets in a MX PDU
o Traffic Class ID (e.g. 1 byte): an unsigned integer to identify the
  traffic class of the IP packets in a MX PDU, for example Data Radio
  Bearer (DRB) ID for a cellular connection
o Sequence Number (e.g. 2 bytes): an auto-incremented integer to
  indicate order of transmission of the IP packet, needed for lossless
  switching or multi-link (path) aggregation.
o Packet Length (e.g. 2 bytes): the length of the first IP packet, only
  included if a MX PDU contains multiple IP packets, i.e. concatenation
o Fragmentation Control (e.g. 1 Byte): to provide necessary information
  for re-assembly, only needed if a MX PDU carries fragments, i.e.
  o Bit #7: a More Fragment (MF) flag to indicate if the fragment is
     the last one or not
  o Bit #0~#6: Fragment Offset (in units of fragments) to specify the
     offset of a particular fragment relative to the beginning of the
     original unfragmented IP datagram

Moreover, the following fields of the IP header of the MX PDU are
changed as follows:

o  Protocol Type: "114" to indicate that the presence of MX trailer
(i.e. the trailer based MAMS u-plane protocol is a "0-hop" protocol,
not subject to IP routing)

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o  IP length: add the length of "MX Trailer" to the length of the
original IP packet
o  IP checksum: recalculate after changing "Protocol Type" and "IP

The MX u-plane protocol can support multiple Anchor connections
simultaneously, each of which is uniquely identified by Connection ID.
It can also support multiple traffic classes per connection, each of
which is identified by Traffic Class ID.

Moreover, the MX trailer format MAY be negotiated dynamically between
NCM and CCM. For example, NCM can send a control message to indicate
which of the above fields SHOULD be included for individual delivery
connection, on downlink and uplink, respectively.

4.3  MPTCP-based MX Convergence Layer


4.4   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 [MPPRoxy] [MPPlain] and another instance can be Trailer based.
The MX Adaptation for each can be either UDP tunnel or IPsec. IPSec may
be set up for network paths considered untrusted by the operator, to
protect the TCP subflow between client and MPTCP proxy traversing that
network path.

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.

5  Security Considerations

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

6  IANA Considerations


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7  Contributing Authors

The editors gratefully acknowledge the following additional
contributors in alphabetical order: Hema Pentakota/Nokia, Satish

8  References

8.1  Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
             Internet Protocol", RFC 4301, DOI10.17487/RFC4301,
             December 2005, <http://www.rfc-editor.org/info/rfc4301>.

8.2  Informative References

   [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
             Security Version 1.2", RFC 6347, January

   [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>.

   [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-

   [MPProxy] X. Wei, C. Xiong, and E. Lopez, "MPTCP proxy mechanisms",

   [MPPlain] M. Boucadair et al, "An MPTCP Option for Network-Assisted
             MPTCP", https://www.ietf.org/id/draft-boucadair-mptcp-

   [MAMS] S. Kanugovi, S. Vasudevan, F. Baboescu, and J. Zhu, "Multiple
             Access Management Protocol",

   [MAMS_CP] S. Kanugovi, et al., "Control Plane Protocols and
             Procedures for Multiple Access Management Services"

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Authors' Addresses

   Jing Zhu


   Email: jing.z.zhu@intel.com

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