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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT                                       John Kaippallimalil
Intended Status: Informational                                    Huawei
Expires: January 7, 2013                                    July 6, 2012


            Mapping PMIP Quality of Service in WiFi Network
              draft-kaippallimalil-netext-pmip-qos-wifi-00


Abstract

   This document proposes a mapping for PMIP QoS parameters of each
   mobility session that a WLC configures on a WiFi Access Point. In
   particular there is a recommendation for consistent mapping between
   DSCP and QCI to 802.11e parameters. The document also discusses that
   these QoS parameters can be used by the WiFi Access Point to provide
   priority based services based on contention in WiFi radio network or
   reservation based services in contention free cycles in the WiFi
   radio network.


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
   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.




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   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 . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2 Definitions  . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.3 Abbreviations  . . . . . . . . . . . . . . . . . . . . . . .  3
   2. QoS Mechanisms  . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1 QoS in 3GPP Networks . . . . . . . . . . . . . . . . . . . .  4
     2.2 QoS in 802.11 Networks . . . . . . . . . . . . . . . . . . .  4
   3. QoS Configuration . . . . . . . . . . . . . . . . . . . . . . .  5
     3.1 Architecture Context . . . . . . . . . . . . . . . . . . . .  5
     3.2 QoS Configuration on WiFi AP . . . . . . . . . . . . . . . .  6
   4. Mapping Recommendations and Default Values  . . . . . . . . . .  7
   5. Security Considerations . . . . . . . . . . . . . . . . . . . .  9
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  9
   7  References  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     7.1  Normative References  . . . . . . . . . . . . . . . . . . .  9
     7.2  Informative References  . . . . . . . . . . . . . . . . . .  9
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10




















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1  Introduction

   This document provides information on how to map 3GPP QoS profile to
   802.11e. When a user with subscription in the 3GPP network attaches
   to a 3GPP EPC via a WiFi access, the 3GPP network can provides a QoS
   profile for each mobility session over PMIP (S2a interface) and
   during authorization over Diameter (STa interface). [PMIP-QoS]
   proposes a mechanism by which QoS policy parameters in the 3GPP EPC
   (Enhanced Packet Core) are obtained by the WLC (MAG). [PMIP-QoS]
   further describes how DSCP obtained via PMIP is mapped to 802.1p and
   used by WiFi APs to prioritize IP flows to/from a host (UE).

   The QoS policy for the user should be applied in the WiFi radio
   network and to upstream user flows in the IP backhaul network. DSCP
   or 802.1D mapping can be used in the 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, it is useful to have a
   consistent mapping of QoS parameters and values between 3GPP and
   802.11e. Recommendations to map a 3GPP QCI to DSCP for mobility
   sessions are available in [PMIP-QoS]. This document adds the explicit
   configuration of QoS per PMIP mobility session to a WiFi access
   (radio access).

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



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   MBR          Maximum Bit Rate
   PDN-GW       Packet Data Network Gateway
   QCI          QoS Class Indicator
   QoS          Quality of Service
   Tspec                Traffic Conditioning Spec
   UE           3GPP User Equipment
   WLC          Wireless Controller



2. QoS Mechanisms

2.1 QoS in 3GPP Networks

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

   A 3GPP UE 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 802.11 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



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   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. QoS Configuration

3.1 Architecture Context

   This section describes the context in which the 3GPP QoS
   configuration is applied to traffic flows handled by a WiFi Access
   Point. In this case, a 3GPP user attaches to the WiFi network and
   accesses services in the 3GPP EPC. The 3GPP EPC provides QoS
   parameters when the user is authorized (subscribed QoS) and for each
   connection to EPC as described in [PMIP-QoS]. At this point, the WLC
   has 3GPP QoS parameters for each user attached to the EPC. Access
   Points can use DSCP values in downlink IP flows associated with a
   user to provision 802.11e priority in WiFi network.

   In [PMIP-QoS], the Access Point (AP) is not directly provisioned with
   QoS for a user connection. As a result, the AP is only able to
   prioritize flows based on observed DSCP values on downlink flows.
   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.
   This solution recommends provisioning the AP with QoS policy
   associated to a user.

   The paragraphs that follow outline the overall architecture and the
   next sub-chapter provides details on QoS parameters provisioned in
   the AP.











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                                       +-----+
                                       | AAA |
                                       +--+--+
                                          |
                                          | STa
                                          |
       WiFi AP                    WLC(MAG)|
      +---------------+           +-------|-------+
      |  +---------+  |  802.11   |  +----v----+  |  PMIP-QoS +--------+
      |  |QoS-Ctrl <-----------------+QoS-Ctrl <--------------+ PDN-GW +
      |  +----+----+  |   QoS     |  +----+----+  |   (S2a)   +---+----+
      |       |       |           |       |       |               |
      |  +----v----+  |   _____   |  +----V----+  |    ________   |
      |  |   PEP   +-----/ IP  )-----+   PEP   +------/   IP   )  |
      |  +---------+  |  Network  |  +---------+  |   | Network|--+
      +---------------+  (     /  +---------------+   (        /
                          -----                        --------
        Figure 1: Provisioning 802.11 QoS parameters on WiFi AP

   Figure 1 provides a view of the architecture in which the 3GPP QoS is
   provisioned on the AP. The end user (not shown in figure) attaches to
   the 3GPP EPC (Enhanced Packet Core) via the WiFi AP and WLC.  The two
   QoS provisioning interfaces shown in the figure are STa for
   delivering subscriber policy as part of user authorization, and S2a
   PMIP for each connection to the EPC. QoS-Ctrl (logical entity) in WLC
   provisions QoS to the WLC PEP as described in [PMIP-QoS]. In
   addition, the WLC translates the 3GPP QoS policy to equivalent
   parameters for 802.11e and IP flows and sends them to the WiFi AP.
   The protocols used to exchange QoS parameters between the WLC and AP
   are not discussed in this document. The AP maps the received QoS
   policy configuration and applies them to upstream and downstream
   forwarding of data packets on the WiFi radio network. The AP also
   applies these QoS policies for upstream user IP flows to the WLC.

   The WLC takes subscriber policy and policy per connection to EPC
   network and translates it to equivalent 802.11e  and DSCP parameters.
   It should be noted that 3GPP users may have more than one connection
   and policy associated with each of them. The WLC should provide the
   AP with a policy that applies to each user (MAC address in WiFi
   network) and parameters per IP flow.



3.2 QoS Configuration on WiFi AP

   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:



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   - Hardware (MAC) address of host for which PMIP session is
     established.
   - IP prefix or address of PMIP mobility session
   - DSCP. Diffserv PHB value of PMIP QoS for the mobility session.
   - QCI. The WLC may provide 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
     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 user flows. The
   WiF 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 backhaul
   to the WLC. For contention free scheduling (based on HCCA), 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 drops 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.



4. 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.









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     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: QoS Mapping between QCI, WMM, 802.11e AC






































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5. 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.



6. IANA Considerations

   No IANA assignment of parameters are required in this document.



7  References

7.1  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.




7.2  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.

   [RFC 3246]

   [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

   EMail: john.kaippallimalil@huawei.com



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