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Versions: 00 01 02 03 04                                                
INTERNET-DRAFT                                       John Kaippallimalil
Intended Status: Informational                                    Huawei
Expires: April 23, 2013                                 October 20, 2012


            Mapping PMIP Quality of Service in WiFi Network
              draft-kaippallimalil-netext-pmip-qos-wifi-01


Abstract

   This document proposes a model for mapping PMIP QoS parameters of a
   mobile network session to the corresponding connection at a WiFi
   Access Point. In congested network conditions, it is possible that a
   user's flows from the WiFi AP are metered and shaped at the WLC to
   match the bandwidth constraints or service priority of the user's
   subscription and PMIP QoS parameters. Applying similar QoS policing
   at the WiFi AP allows optimal use of scarce radio 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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Copyright and License Notice



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   Copyright (c) 2012 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. Policy Provisioning Architecture  . . . . . . . . . . . . . . .  5
   4. Connections and QoS Mapping . . . . . . . . . . . . . . . . . .  7
     4.1 Connection Model . . . . . . . . . . . . . . . . . . . . . .  7
     4.2 PMIP - 802.11e QoS Configuration . . . . . . . . . . . . . .  8
   5. 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 provides a description of how the QoS profile for a
   PMIP session maps to QoS for the corresponding 802.11 connection
   segment of the MN (Mobile Node). When a  mobile network user attaches
   via a WiFi access, the WLC (MAG) obtains a QoS profile for each PMIP
   session. [PMIP-QoS] proposes 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).

   [PMIP-QoS] outlines a model in which the QoS in PMIP flows can be
   reflexively mapped to IP flows over 802.11 or backhaul network. The
   WiFi AP can infer the QoS priority associated with an IP flow based
   on the the DSCP value in the downstream packets of the PMIP flow, and
   apply the same priority to upstream packets of the flow. It should be
   noted that the WLC (MAG) uses DSCP priority as well as other
   parameters of the MN such as subscribed bandwidth and service
   priority in [PMIP-QoS] to police IP flows of the MN. In congested
   network conditions, it is possible that upstream flows from the WiFi
   AP are throttled by the WLC to match the bandwidth constraints or
   service priority. This will result in sub-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.  In addition to uneven policing between WiFi AP and WLC,
   when the WiFi network itself is congested, the MN subscribed
   bandwidth and service priority can be useful to schedule and use the
   radio network resources more effectively.

   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
   of QoS parameters and values between 3GPP and 802.11e is needed.
   Recommendations to map 3GPP QCI to DSCP for mobility sessions are



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   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
   QoS parameters that can be used to provide service differentiation in
   multi vendor and operator deployments. The concept of a bearer is



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   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. Policy Provisioning Architecture

   This section describes the architecture in which the PMIP QoS
   configuration of MN sessions is applied to the corresponding traffic



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   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 1: 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
   WLC PEP as described in [PMIP-QoS].
   In this solution, 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



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   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 in the WiFi radio network. The
   AP also applies these QoS policies for upstream user IP flows to the
   WLC. The WLC should provide the AP with a policy that applies to each
   MN (MAC address in WiFi network) and parameters per IP flow. This
   model is described further in the following chapter.




4. Connections and QoS Mapping

4.1 Connection Model

   MNs that attach to the mobile network have QoS policies associated to
   the corresponding PMIP connection. This section outlines the
   connection model for 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 2: MN Connection and QoS Mapping


   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), or an IP cpnnection to the mobile network (MN2, conn2a,
   PMIP-2) and an IP connection that is offloaded at the WLC (MN2,
   conn2b, offload). The connection segment between MN and WLC may be IP
   connections, or  tunneled connections such as IPSec.

   For an MN - WLC connection segment with IP address configured via
   PMIP (e.g. MN2 conn2a), the corresponding PMIP QoS would be



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   applicable to flows with this IP address and MAC address.
   For tunneled connections in MN - WLC segment (e.g. MN1 conn-1), MN1
   first gets a local IP address from the WLC. MN1 then establishes an
   IPSec connection to the WLC and in the IKE signaling indicates
   parameters for PMIP connection setup.  The corresponding PMIP QoS
   parameters are applicable to flows identified by local IP address,
   port (IPSec source port at MN1) and MAC address.
   WiFi AP may use a default QoS profile for connection flows that are
   offloaded (e.g. MN2 conn2b in figure).

   The WiFi AP would get QoS traffic filters corresponding to PMIP
   flows. These flows would be identified by the tuple {MAC, IP address,
   port}. The port field may be specified for tunneled or NATed
   connections and wildcarded otherwise.




4.2 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 of tunneled flow or NATed connection.
   - 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
     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



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   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 (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.



5. 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 draft that the protocol between WLC and AP is not considered
   further here. There needs to be some work to determine the protocol
   parameters and other details if it is desired that WLC and AP should
   interwork.
   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 flows introduce cases where the same IP flow (5-tuple) can
   have multiple DSCP values - for example when the IP flow carries
   audio and video applications. This would impact the QCI and DSCP
   parameters of IP flows, but this is not only this description that is
   affected. A
   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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