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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT                                       John Kaippallimalil
Intended Status: Informational                                    Huawei
Expires: October 23, 2013                                 April 21, 2013


            Mapping PMIP Quality of Service in WiFi Network
              draft-kaippallimalil-netext-pmip-qos-wifi-02


Abstract

   This document proposes a model for configuring and mapping PMIP QoS
   parameters of a mobile network session to the corresponding
   connection at a WiFi Access Point. In congested network conditions,
   it is useful for an MN's flows to be policed and shaped at the WLC
   and WiFi AP to match  bandwidth constraints or service priority of
   the user's subscription. Applying similar QoS management at the WiFi
   AP and WLC allows optimal use of network resources. Currently, the
   WiFi AP does not have information on the MNs subscribed bandwidth, or
   relative priority of its flows or services for per user QoS handling
   at the WiFi AP. This document provides a model for mapping PMIP QoS
   to corresponding 802.11e QoS parameters.



Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
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   http://www.ietf.org/1id-abstracts.html

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Copyright and License Notice



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   Copyright (c) 2013 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. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . .  4
   2. QoS Mechanisms  . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1. QoS in Mobile Networks  . . . . . . . . . . . . . . . . . .  4
     2.2. QoS in WiFi Networks  . . . . . . . . . . . . . . . . . . .  5
   3. Connection Model  . . . . . . . . . . . . . . . . . . . . . . .  5
   4. Policy Provisioning Architecture  . . . . . . . . . . . . . . .  7
   5. QoS Configuration and Mapping . . . . . . . . . . . . . . . . .  8
     5.1. PMIP - 802.11e QoS Configuration  . . . . . . . . . . . . .  8
     5.2. Mapping Recommendations and Default Values  . . . . . . . .  9
   6. Next Steps  . . . . . . . . . . . . . . . . . . . . . . . . . . 10
   7. Security Considerations . . . . . . . . . . . . . . . . . . . . 11
   8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     9.1. Normative References  . . . . . . . . . . . . . . . . . . . 11
     9.2. Informative References  . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12















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1. Introduction

   This document describes a means for the QoS profile of a PMIP session
   to be applied to QoS on the 802.11 connection segment of the MN
   (Mobile Node). A mobile network may dynamically provision QoS for its
   users attached via a WiFi access and PMIP backhaul. [PMIP-QoS]
   defines a mechanism by which QoS policy parameters in the mobile
   network are delivered from the LMA to the the WLC (MAG) using PMIP
   QoS extensions. [PMIP-QoS] further describes how the DSCP value for
   the PMIP session is mapped to corresponding 802.1p value that may be
   used by IP backhaul network or WiFi APs to prioritize IP flows of a
   host (MN).

   While [PMIP-QoS] defines how mobile network QoS can be applied to
   PMIP flows, the WiFi AP has to reflexively map QoS for IP flows.
   Based on the observed DSCP values in  downstream packets of an IP
   flow, the WiFi AP provides the same level of QoS in the upstream
   direction. In addition, the WiFi AP may use the downstream DSCP
   values to determine the scheduling priority in the 802.11 network.
   Based on [PMIP-QoS], the WLC (MAG) can use DSCP priority as well as
   other parameters of the MN such as subscribed bandwidth and service
   priority to police IP flows of an MN.  The WiFi AP on the other hand
   relies on DSCP priority for scheduling and policing IP flows of an MN
   since it does not have per subscriber policy information of an MN. In
   congested network conditions, it is not possible for the WiFi AP to
   differentiate between MNs that have premium subscriptions. In
   addition, it is possible that upstream flows from the WiFi AP are
   throttled by the WLC to match the bandwidth constraints or service
   priority. This can result in sub-optimal use of network resources. In
   order for the WiFi AP to differentiate on per flow and per user
   basis, it needs information on the MNs subscribed bandwidth and other
   policy information.

   This proposal aims to provide the WiFi AP with per MN QoS profile to
   allow more effective overall use of network resources - both WiFi
   radio and IP backhaul. The QoS parameters needed are available to the
   WLC during MN authorization and establishment of the PMIP session
   with QoS extensions. Since an MN may establish tunneled IP flows,
   direct IP connections or offloaded connections, the relationship of
   PMIP QoS to 802.11e QoS is explained. It is possible that an MN (with
   a single 802.11 interface) has more than one PMIP session. The QoS
   policy for the MN may be applied by the AP to schedule and control
   WiFi radio network resources and upstream user flows in the IP
   backhaul network. If per session QoS policy is not available, the AP
   may be provisioned to apply QoS based on the subscribed QoS values
   obtained during 3GPP user authorization.

   In order to provision QoS in the WiFi network, a consistent mapping



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   of QoS parameters and values between 3GPP and 802.11e is needed.
   Recommendations to map 3GPP QCI to DSCP for mobility sessions are
   available in [PMIP-QoS]. This document adds the configuration of QoS
   per PMIP mobility session to a WiFi radio access.

   The rest of the document is organized as follows. Chapter 2 outlines
   the QoS mechanisms in 3GPP mobile networks and 802.11 networks.
   Chapter 3 provides an overview of the architecture in which QoS is
   provisioned on the WiFi AP. Chapters 4 and 5 describe the connection
   model in the access network and the QoS mapping itself.

1.1. Terminology

   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].

1.2. Definitions





1.3. Abbreviations

   3GPP         Third Generation Partnership Project
   AAA          Authentication Authorization Accounting
   ARP          Allocation and Retention Priority
   AP           Access Point
   DSCP         Differentiated Services Code Point
   EPC          Enhanced Packet Core
   GBR          Guaranteed Bit Rate
   MAG          Mobility Access Gateway
   MBR          Maximum Bit Rate
   MN           Mobile Node
   PDN-GW       Packet Data Network Gateway
   QCI          QoS Class Indicator
   QoS          Quality of Service
   Tspec                Traffic Conditioning Spec
   WLC          Wireless Controller


2. QoS Mechanisms

2.1. QoS in Mobile Networks

   3GPP has standardized QoS for EPC (Enhanced Packet Core) from Release
   8 [TS 23.107]. 3GPP QoS policy configuration defines access agnostic



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   QoS parameters that can be used to provide service differentiation in
   multi vendor and operator deployments. The concept of a bearer is
   used as the basic construct for which the same QoS treatment is
   applied for uplink and downlink packet flows between the MN (host)
   and gateway [TS23.401]. A bearer may have more than one packet filter
   associated and this is called a Traffic Flow Template (TFT). The IP
   five tuple (IP source address, port, IP destination, port, protocol)
   identifies a flow.

   The access agnostic QoS parameters associated with each bearer are
   QCI (QoS Class Identifier), ARP (Allocation and Retention Priority),
   MBR (Maximum Bit Rate) and optionally GBR (Guaranteed Bit Rate). QCI
   is a scalar that defines packet forwarding criteria in the network.
   Mapping of QCI values to DSCP is well understood and GSMA has defined
   standard means of mapping between these scalars [GSMA-IR34].

   An MN may have more than one IP addresses associated with the same
   hardware (MAC) address corresponding to each of the networks than it
   is attached to. This corresponds to more than one PMIP mobility
   session for which QoS is provisioned in the WLC.


2.2. QoS in WiFi Networks

   802.11e [802.11e] defined by IEEE provides an enhancement of the MAC
   layer in WiFi networks to support QoS. Basic 802.11 WiFi uses CSMA
   and collision avoidance to provide best effort access to the medium.
   802.11e defines a Hybrid Coordination Function (HCF) that provides a
   priority based access and also admission control based access.

   HCF contention based channel access provides prioritized access to
   the 802.11 medium. Four access categories (AC) are defined based on
   traffic type. Each arriving frame is mapped into one of four FIFO
   queues corresponding to different user priority (UP) values. The
   highest priority frame is transmitted when access is obtained in a
   contention window. Access categories and their mapping to 802.1D user
   priorities is provided [802.11e].

   HCF controlled channel access uses a central coordinator to provide
   contention free access to the medium based on admission control. The
   HCCA (HCF Controlled Channel Access) based scheduling can use
   configured policies to grant exclusive access to a QSTA (user) for
   limited contention free slots.




3. Connection Model



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   MNs that attach to a mobile network via a WiF AP and WLC are
   provisioned with IP addresses corresponding to each PMIP session.
   Each of the IP sessions at MN has QoS policies associated to it. This
   section outlines the connection model in detail and  QoS mapping on
   the WiFi AP.



                       WiFi AP                   WLC(MAG)
                      +----------+              +-------------+
                      |+--------+|              | +---------+ |
      +---+           ||  PEP   ||              | +   PEP   + |
      |MN |           |+--------+|              | +---------+ |
      | 1 ===========================[conn-1]=========<X>=======[PMIP-1]
      +---+           |          |              |             |
      +---+           |          |              |             |
      |MN +--------------------------[conn2a]---------<X>=======[PMIP-2]
      | 2 +--------------------------[conn2b]---------<X>     |
      +---+           +----------+              +------|------+
                                                       |
                                                       V
                                                [offload path]

        Figure 1: MN Connection model


   An MN may establish a session to the mobile network or may have a
   session that is offloaded to the internet from the WLC.
   Figure 2 shows MN1 and MN2 attached to the WLC via a WiFi AP. An MN
   may have a tunneled connection to the mobile network (MN1, conn-1,
   PMIP-1), (MN2, conn2a, PMIP-2) and an IP connection that is offloaded
   at the WLC (MN2, conn2b, offload). The specification for IP
   tunnel/connection between MN and WLC are out of the scope of this
   document.

   For an MN - WLC connection segment with IP address configured via
   PMIP (e.g. MN2 conn2a), the corresponding PMIP QoS would be
   applicable to MN flows with this IP address.
   For connection segment that is offloaded at WLC, the IP address is
   configured by the WLC. As in the case of PMIP connections, QoS is
   provisioned for MN flows with this IP address

   In both cases - PMIP session related connection segment, or offload
   connection segment - the WiFi AP gets QoS traffic filters and
   configuration from the WLC. The QoS profile would be identified by
   the IP address for the PMIP / offload session.





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4. Policy Provisioning Architecture

   This section describes the architecture in which the PMIP QoS
   configuration of MN sessions is applied to the corresponding traffic
   flows in the WiFi Access Point. Following MN attach to the WiFi
   network and authentication with the mobile network, the WLC gets QoS
   parameters and other policy for the authorized MN. When the PMIP
   connection is created, the PDN-GW returns QoS policy using [PMIP-QoS]
   extensions.

   In [PMIP-QoS], the Access Point (AP) is not directly provisioned with
   QoS for an MN connection. As a result, the AP is only able to
   prioritize flows based on observed downlink DSCP values.
   Additionally, the AP does not know the maximum bandwidth of a
   subscriber or flow to be applied on the WiFi radio network. This can
   result in sub-optimal utilization of scarce WiFi network resources,
   and of the overall access network. This solution provides a
   description to provision the AP with QoS policy associated to an MN.

   The paragraphs that follow outline the overall architecture and
   subsequent chapters provide details on QoS parameters provisioned in
   the AP.


                                          +-----+
                                          | AAA |
                                          +--+--+
                                             |
                                             |Auth
                                             |
                  WiFi AP            WLC(MAG)|
                 +----------+         +------|------+
                 |+--------+|   QoS   | +----v----+ | PMIP-QoS +------+
                 ||QoS-Ctrl<------------+QoS-Ctrl <------------+PDN-GW+
                 |+---+----+| Policy  | +----+----+ |          +--+---+
                 |    |     |         |      |      |             |
          801.11 |+---v----+|  _____  | +----V----+ |   ________  |
      [MN]--------+  PEP   +--/ IP  )---+   PEP   +----/   IP   ) |
                 |+--------+| Network | +---------+ |  | Network|-+
                 +----------+ (     / +-------------+  (        /
                               -----                    .------.

        Figure 2: Architecture for provisioning QoS Policy on WiFi AP

   Figure 1 provides an overview of the architecture in which QoS for an
   MN is provisioned on the AP. MN QoS policy from initial session
   authorization and PMIP connection establishment is provisioned in the
   WLC QoS-Ctrl (logical function). QoS-Ctrl in WLC installs QoS to the



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   WLC PEP as described in [PMIP-QoS].
   The WLC translates 3GPP QoS policy to equivalent parameters for IP
   flows and applies them for scheduling and policing.

   In this solution, the WLC sends policy information for an MNs PMIP
   sessions to the WiFi AP. The protocols used to exchange QoS
   parameters between the WLC and AP are not discussed in this document.
   The AP can use the received QoS policy configuration and applies them
   to upstream and downstream forwarding of data packets in the WiFi
   radio network. The AP can also apply these QoS policies for upstream
   user IP flows to the WLC.

   An MN may have more than one PMIP session at any given time. Each of
   these PMIP sessions can have different policy parameters. The WLC
   provides the WiFi AP with a policy corresponding to each of these
   PMIP sessions. Since each PMIP session configures an IP address for
   the MN, the policy can be sent per IP address of MN that corresponds
   to the PMIP session. This model is described further in the following
   chapter.

   If the MN connection at WLC is offloaded to the internet, there is no
   PMIP session setup to the mobile network. In this case, the WLC
   should use the subscriber policy obtained during authorization. The
   WiFi AP is provisioned as for other sessions. The WLC provides the
   WiFi AP with QoS parameters for the MN IP address used for the
   offload connection.


5. QoS Configuration and Mapping

5.1. PMIP - 802.11e QoS Configuration

   The WiFi Access Point (AP) gets QoS configuration per IP session from
   the WLC. The QoS information per IP session provided to the AP
   includes:
   - Hardware (MAC) address of host for which PMIP session is
     established.
   - IP prefix or address of PMIP mobility session.
   - IP port address (used for NATed connections).
   - DSCP. Diffserv PHB value of PMIP QoS for the mobility session.
   - QCI. The WLC provides the 3GPP QCI value if available, for example,
     from authorization profile of APN (i.e. subscribed values per
     established PMIP mobility session).
   - ARP (Allocation and Retention Priority). This value is obtained
     from the PMIP QoS for the mobility session. It determines the
     priority of a flow (1 has highest priority).
   - MBR (Maximum Bit Rate) for mobility session uplink and downlink.
     This should not exceed the AMBR (Aggregate MBR) of the



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     subscription.
   - GBR (Guaranteed Bit Rate) for mobility session uplink and downlink,
     if required.

   The WiFi AP uses the above QoS configuration to implement
   classification, admission control and forwarding of MN flows. The
   WiFi AP maps DSCP (or QCI) to 802.11e AC (Access Categories) for each
   IP session / hardware (MAC) address of the host (3GPP user). The
   mapping from DSCP or QCI to 802.11e AC is shown in table in chapter 4
   below.

   In the WiFi radio network, the AP uses 802.11e AC values for
   contention (HCF) based forwarding based on priority. The AP schedules
   downstream flows in the WiFi radio network and for upstream IP
   backhaul to the WLC. For contention free scheduling, the WiFi AP
   additionally uses the  QoS configuration per user to admit flows
   based on 802.11e ADDTS (ADD TSpec) requests from the host (3GPP
   user). The WiFi AP may drop packet that fall outside the configured
   MBR and GBR. In case of severe radio congestion, the WiFi AP can use
   ARP in addition to DSCP drop precedence to determine the flows to be
   dropped.


5.2. Mapping Recommendations and Default Values

   The table below outlines a recommended mapping between 3GPP QCI,
   and 802.11e Access Category (AC) priorities. QCI packet delay budget
   and packet error loss rate may be used by the WiFi access point in
   scheduling contention free access when HCCA scheduling is used.


     QCI    DSCP    802.11e AC     Example 3GPP service
    -------------------------------------------------------------
      1      EF      3 AC_VO      conversational voice
      2      EF      3 AC_VO      conversational video
      3      EF      3 AC_VO      real-time gaming
      4     AF41     2 AC_VI      buffered streaming
      5     AF31     2 AC_VI      IMS signaling
      6     AF31     2 AC_VI      buffered streaming
      7     AF21     0 AC_BE      interactive gaming
      8     AF11     0 AC_BE      web access
      9      BE      1 AC_BK      e-mail

        Table 1: QoS Mapping between QCI, WMM, 802.11e AC







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6. Next Steps

   This document has described a basic model for mapping PMIP QoS
   parameters to 802.11e parameters. However, there are a few questions
   that need to be explored further.

   The protocol between WLC and AP is not discussed in this document.
   There needs to be work to determine the protocol specification if it
   is desired that WLC and AP should interwork for QoS capability.

   Another aspect is this draft does not describe multiple PDN
   connections per MN in much detail. This is work in progress in 3GPP
   and the results should be compatible with the model in this draft.

   RTC Web impact to 3GPP networks is currently being studied. There are
   several technical options being considered by 3GPP at this time. If
   the chosen solution requires more than one type of DSCP/QoS to be
   configured per PMIP session/IP connection segment - for example if
   audio and video flows use the same IP session - then this capability
   is required for WLC - AP configuration also.

   Finally, the QoS values listed in the table in chapter 5 needs to be
   aligned with [PMIP-QoS] and GSMA.




























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7. Security Considerations

   This document describes mapping of 3GPP QoS profile and parameters to
   IEEE 802.11e parameters. No security concerns are expected as a
   result of using this mapping.



8. IANA Considerations

   No IANA assignment of parameters are required in this document.



9.  References

9.1. Normative References

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

   [RFC1776]  Crocker, S., "The Address is the Message", RFC 1776, April
              1 1995.

   [TRUTHS]   Callon, R., "The Twelve Networking Truths", RFC 1925,
              April 1 1996.




9.2. Informative References

   [EVILBIT]  Bellovin, S., "The Security Flag in the IPv4 Header",
              RFC 3514, April 1 2003.

   [RFC5513]  Farrel, A., "IANA Considerations for Three Letter
              Acronyms", RFC 5513, April 1 2009.

   [RFC5514]  Vyncke, E., "IPv6 over Social Networks", RFC 5514, April 1
              2009.

   [PMIP-QoS] Liebsch, et al., "Quality of Service Option for Proxy
              Mobile IPv6", draft-ietf-netext-pmip6-qos-00, June 2012.

   [RFC 2211] Wroclawski, J., "Specification of the Controlled Load
              Quality of Service", RFC 2211, September 1997.

   [RFC 2212] Shenker, S., Partridge, C., and R. Guerin, "Specification



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              of Guaranteed Quality of Service", RFC 2212, September
              1997.

   [RFC 2216] Shenker, S., and J. Wroclawski, "Network Element QoS
              Control Service Specification Template", RFC 2216,
              September 1997.

   [TS23.107] Quality of Service (QoS) Concept and Architecture, Release
              10, 3GPP TS 23.107, V10.2.0 (2011-12).

   [TS23.207] End-to-End Quality of Service (QoS) Concept and
              Architecture, Release 10, 3GPP TS 23.207, V10.0.0 (2011-
              03).

   [TS23.401] General Packet Radio Service (GPRS) enhancements for
              Evolved Universal Terrestrial Radio Access Network (E-
              UTRAN) access (Release 11), 3GPP TS 23.401, V11.2.0 (2012-
              06).

   [TS23.203] Policy and Charging Control Architecture, Release 11, 3GPP
              TS 23.203, V11.2.0 (2011-06).

   [TS29.212] Policy and Charging Control over Gx/Sd Reference Point,
              Release 11, 3GPP TS 29.212, V11.1.0 (2011-06).

   [802.11e]  IEEE, "IEEE part 11: Wireless LAN Medium Access
              Control(MAC) and Physical Layer (PHY) specifications.
              Amendment 8: Medium Access Control (MAC) Quality of
              Service Enhancements" 802.11e-2005, 22 September 2005.

   [GSMA-IR34]Inter-Service Provider Backbone Guidelines 5.0, 22
              December 2010






Authors' Addresses


   John Kaippallimalil
   5340 Legacy Drive, Suite 175
   Plano Texas 75024

   E-Mail: john.kaippallimalil@huawei.com





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