Internet DRAFT - draft-kaippallimalil-netext-pmip-qos-wifi
draft-kaippallimalil-netext-pmip-qos-wifi
INTERNET-DRAFT John Kaippallimalil
Intended Status: Informational Huawei
Expires: August 14, 2014 Rajesh S. Pazhyannur
Cisco
Parviz Yegani
Juniper
February 10, 2014
Mapping 802.11 QoS in a PMIPv6 Mobility Domain
draft-kaippallimalil-netext-pmip-qos-wifi-04
Abstract
This document provides recommendations on procedures and mapping of
QoS parameters between 802.11 and PMIPv6. QoS parameters in 802.11
that reserve resources for 802.11 streams should be mapped to PMIP
QoS resources for IP sessions and flows. QoS reservation sequences in
802.11 should allow cases where MN initiate resource reservation, as
well as cases where the network initiates resource reservation.
Additionally, it should be possible for QoS parameters for PMIPv6
flows and mobility sessions to be mapped to 802.11 traffic stream
reservations. The sequences and parameters to be mapped to provide a
consistent behavior across 802.11 and PMIPv6 QoS are described here.
Status of this Memo
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Copyright and License Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . 6
2. End-to-End QoS with no Admission Control . . . . . . . . . . . 6
3. End-to-End QoS with Admission Control . . . . . . . . . . . . . 8
3.1. Case A: MN Initiates QoS Request . . . . . . . . . . . . . 9
3.2. Case B: Network Initiates QoS Signaling (802.11aa based) . 11
3.3. Case C: Hybrid (Network Initiated for PMIP, MN initiated
in 802.11) . . . . . . . . . . . . . . . . . . . . . . . . 12
3.4. Case D: Network Initiated Release . . . . . . . . . . . . . 14
3.5. Case E: MN Initiated Release . . . . . . . . . . . . . . . 16
3.6. Service Guarantees in 802.11 . . . . . . . . . . . . . . . 17
4. Mapping of QoS Parameters . . . . . . . . . . . . . . . . . . . 17
4.1 Connection Mapping . . . . . . . . . . . . . . . . . . . . . 18
4.2. QoS Class . . . . . . . . . . . . . . . . . . . . . . . . . 18
4.3. Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . . 19
4.4. Preemption Priority . . . . . . . . . . . . . . . . . . . . 20
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 20
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 21
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 21
7.1. Normative References . . . . . . . . . . . . . . . . . . . 21
7.2. Informative References . . . . . . . . . . . . . . . . . . 21
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 22
Appendix A: QoS in 802.11, PMIPv6 and 3GPP Networks . . . . . . . 23
A.1. QoS in IEEE 802.11 Networks . . . . . . . . . . . . . . . . 23
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A.2. QoS in PMIPv6 Mobility domain . . . . . . . . . . . . . . . 23
A.3. QoS in 3GPP Networks . . . . . . . . . . . . . . . . . . . 24
1. Introduction
802.11 networks can currently apply QoS policy by using ALG
(Application Level Gateway) to detect an application (e.g. SIP
signaling) and then install QoS for the corresponding IP flow on the
Wireless LAN Controller (WLC)/ Access Point (AP). However, this is
not a general mechanism and would require ALG or detection of
application level semantics in the access to install the right QoS.
[PMIP-QoS] describes a application neutral procedure to obtain QoS
for PMIPv6 flows and sessions. However, there are differences in
parameters and procedures that need to be mapped between PMIPv6 QoS
and 802.11. PMIPv6 has the notion of QoS for mobility sessions and
flows while in 802.11 these should correspond to QoS for 802.11 data
frames. Parameters in 802.11 QoS do not always have a one-to-one
correspondence in PMIPv6 QoS. Further, 802.11 and PMIP QoS procedures
need to be aligned based on whether QoS setup is triggered by the MN
or pushed by the the network, as well as working with WMM or 802.11aa
mechanisms.
This document provides information on using PMIPv6 QoS parameters for
an MN connection over a 802.11 access network. The recommendations
here allow for dynamic QoS policy information per Mobile Node (MN)
and session to be configured by the 802.11 access network. PMIPv6
QoS signaling between MAG and LMA provisions the per MN QoS policies
in the MAG. In the 802.11 access network modeled here, the MAG is
located at the Access Point (AP)/ Wireless LAN Controller (WLC) .
Figure 1 below provides an overview of the entities and protocols.
+--------+ +-------+
| AAA | | PCF |
+---+----+ +---+---+
| |
| |
+----+ +---+----+ +---+---+
| | 802.11 (WMM, 802.11aa) | | PMIPv6 | |
| MN <------------------------> AP/WLC <==========> LMA |
| | (ADDTS, DELTS) | (MAG) | QoS | |
+----+ +--------+ +-------+
Figure 1: QoS Policy in 802.11 Access
MN and AP/WLC use 802.11 QoS mechanisms to setup admission controlled
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flows. The AP/WLC is a MAG that requests for QoS policy from the LMA.
The MN uses ADDTS (Add Traffic Stream) to setup QoS for a traffic
stream between itself and the AP, and DELTS (Delete Traffic Stream)
to delete that stream. In WMM [WMM 1.2.0], the AP advertises if
admission control is mandatory for an access class. Admission control
for best effort or background access classes is not recommended. In
addition to WMM capability, 802.11aa allows for AP/WLC to support an
ADDTS reservation request to the MN. This makes it simpler to support
a PMIPv6 QoS request that is pushed to the AP/WLC.
The parameter mapping recommendations described here support the
procedures by which the 3GPP network provisions QoS per application
dynamically or during authorization of the Mobile Node (MN). However,
the 802.11 procedures described here are not limited to work for just
the 3GPP policy provisioning. If PMIPv6 QoS parameters can be
provisioned on the MAG via mechanisms defined in [PMIP-QoS], the
802.11 procedures can be applied in general for provisioning OoS in a
802.11 network.
PMIPv6 QoS parameters need to be mapped to 802.11 QoS parameters. In
some cases, there is no one-to-one mapping. And in other cases such
as bandwidth, the values received in PMIP should be mapped to the
right 802.11 parameters. This document provides recommendations to
perform QoS mapping between PMIPv6 and 802.11 QoS.
[PMIP-QoS] does not explicitly describe how the QoS signaling and QoS
sub-options map into corresponding signaling and parameters in the
802.11 access network. This mapping and the procedures in the 802.11
network to setup procedures are the focus of this document. The
end-to-end flow spanning 802.11 access and PMIPv6 domain and the QoS
parameters in both segments are described here. Thus, it provides a
systematic way to map the various QoS parameters available in
initial authorization, as well as setup of new sessions (such as a
voice/video call). The mapping recommendations allow for proper
provisioning and consistent interpretation between the various QoS
parameters provided by PMIP QoS, and 802.11.
The rest of the document is organized as follows. Chapter 2 provides
an overview of establishing mobility sessions with no admission
control. These mechanisms are specified in [PMIP QoS] and outlined
here since the mobility session established is the basis for
subsequent admission controlled requests for flows. Chapter 3
describes how end to end QoS with 802.11 admission control is
achieved. The mapping of parameters between 802.11 and PMIP QoS is
described in Chapter 5.
1.1. Terminology
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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
Guaranteed Bit Rate (GBR)
GBR in a mobile network defines the guaranteed (reserved) bit
rate resources of service data flow on a connection (bearer)
[TS23.203].
Maximum Bit Rate (AMBR)
MBR represents the maximum bandwidth of a flow with reservation.
Aggregate Maximum Bit Rate (MBR)
AMBR represents the total bandwidth that all flows of a user is
allowed. AMBR does not include flows with reservation.
Allocation Retention Priority (ARP)
ARP is used in the mobile network to determine the order in which
resources for a flow may be preempted during severe congestion or
other resource limitation. ARP of 1 is the highest priority while
15 is the lowest [TS23.203].
Peak Data Rate
In WMM, Peak Data Rate specifies the maximum data rate in bits
per second. The Maximum Data Rate does not include the MAC and
PHY overheads [WMM 1.2.0].
Mean Data Rate
This is the average data rate in bits per second. The Mean Data
Rate does not include the MAC and PHY overheads [WMM1.2.0]
Minimum Data Rate
In WMM, Minimum Data Rate specifies the minimum data rate in bits
per second. The Minimum Data Rate does not include the MAC and
PHY overheads [WMM 1.2.0].
TSPEC
The TSPEC element in 802.11 contains the set of parameters that
define the characteristics and QoS expectations of a traffic
flow.
TCLAS
The TCLAS element specifies an element that contains a set of
parameters necessary to identify incoming MSDU (MAC Service Data
Unit) that belong to a particular TS (Traffic Stream) [802.11].
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1.3. Abbreviations
3GPP Third Generation Partnership Project
AAA Authentication Authorization Accounting
AMBR Aggregate Maximum Bit Rate
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
PCF Policy Control Function
PDN-GW Packet Data Network Gateway
QCI QoS Class Indicator
QoS Quality of Service
TCLAS Type Classification
TSPEC Traffic Conditioning Spec
WLC Wireless Controller
2. End-to-End QoS with no Admission Control
PMIPv6 and 802.11 QoS with no admission control is specified in [PMIP
QoS]. This section is provided as background here since prior to the
establishment of an admission controlled flow, a mobility session as
described here is established. IETF (RFC 4594) and GSMA have defined
mapping between DSCP and IEEE 802.11 UP (User Priority). The AP/WLC
(MAG) should be pre-configured to use the mapping from one of these
specifications.
An MN that attempts to connect to a 802.11 network typically
authenticates first and may have an authorization profile downloaded.
The AP/WLC may use the QoS profile for the MN for policing flows.
However, the network can obtain more dynamic policy that corresponds
to current mobile network conditions and preferences using PMIP QoS.
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+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
+-------------------------------------------------------------+
| [0] connection setup to mobile network |
+-------------------------------------------------------------+
| | |
| | PBU(QoS-i, ALLOC)[1] |
| |---------------------->| QoS Policy
| | PBA (QoS-r, NEG) [2] |<--------------->
| |<----------------------|
| | |
| | PBU(QoS-r, ALLOC)[3] |
| |---------------------->|
| | PBA (QoS-r, RESP)[4] |
| |<----------------------|
| | |
Figure 2: Default connection setup
[0] MN signals to setup connection. The AP/WLC obtains an
authorization profile that includes QoS information, or may have
an administratively configured profile with QoS information.
[1] The completion of 802.11 and IP setup serves as a trigger for
the MAG (AP/WLC) to request for dynamic QoS parameters. The MAG
sends a PBU containing QoS Option with operation code set to
ALLOCATE, and DSCP, QoS Attributes set to initially authorized
values for the MN's default connection (QoS-i).
This request is for QoS of all flows of a connectivity session
of the MN and includes DSCP, Per-MN-Agg-Max-DL-Bit-Rate, Per-MN-
Agg-Max-UL-Bit-Rate, Per-Session-Agg-Max-DL-Bit-Rate, Per-
Session-Agg-Max-UL-Bit-Rate and Allocation-Retention-Priority
fields derived from the MN initial authorization profile. The
Traffic Selector field should not be present.
[2] The LMA queries the policy server and obtains a response. The
policy server may grant the QoS requested or may change the QoS
levels based on network or other dynamic conditions (QoS-r in
figure). This example assumes that the LMA cannot provide the
QoS requested by the MAG.
The LMA sets the operational code to NEGOTIATE and responds with
downgraded parameters for DSCP, Per-MN-Agg-Max-DL-Bit-Rate, Per-
MN-Agg-Max-UL-Bit-Rate, Per-Session-Agg-Max-DL-Bit-Rate, Per-
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Session-Agg-Max-UL-Bit-Rate and Allocation-Retention-Priority.
The Traffic Selector field is not present since the provisioning
applies to the entire PMIPv6 connectivity session.
[3] The MAG receives the downgraded QoS and sends a revised PBU with
the QoS options that the LMA is prepared to offer. The
operational code is set to ALLOCATE.
[4] The LMA can accept the requested QoS. The LMA sends a PBA
message with the revised QoS options and operational code set to
RESPONSE.
The new QoS values will be used by the MAG to police flows of the MN
and will supercede earlier (or initially) provisioned QoS values. MAG
polices session flows to not exceed Per-Session-Agg-Max-DL-Bit-Rate,
Per-Session-Agg-Max-UL-Bit-Rate. If there are multiple sessions, the
total bandwidth should not exceed Per-MN-Agg-Max-DL-Bit-Rate, Per-MN-
Agg-Max-UL-Bit-Rate.
3. End-to-End QoS with Admission Control
This section outlines a few use cases to illustrate how parameters
and mapping are applied for flows that require admission control.
These cases illustrate the various provisioning sequences and
mechanisms. It is not intended to be exhaustive.
The general procedure here is that a flow that requires admission
control is part of a PMIPv6 connectivity session. QoS options for the
overall session are provisioned as described in section 2. As a
result of some application layer signaling, specific flows of the
application may require admission controlled QoS which can be
provisioned on a per flow basis.
There are two main types of interaction possible to provision QoS for
flows that require admission control - one case is where the MN
initiates the QoS request and the network provisions the resources.
The second is where the network provisions resources as a result of
some out of band signaling (like application signaling). In the
second scenario, if the MN supports 802.11aa, the network can push
the QoS configuration to the MN. If the MN only supports WMM QoS,
then MN requests for QoS for the 802.11 segment and the MAG
provisions based on QoS already provisioned for the MN. These three
cases are described in sections 3.1 - 3.3.
In each of the sequences, QoS parameters need to be mapped between
802.11 and PMIPv6. The table below provides an overview of the
mapping for establishing QoS for an admission controlled flow.
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Further details of the parameters and mappings are provided in
section 4.
+------------------------------+------------------------------+
| MN <--> AP/WLC(802.11) | AP/WLC(MAG) <--> LMA PMIPv6 |
+------------------------------+------------------------------+
| (TCLAS) TCP/UDP IP | Traffic Selector (IP flow) |
| (TCLAS) User Priority | DSCP |
+------------------------------+------------------------------+
| (TSPEC)Minimum Data Rate, DL | Guaranteed-DL-Bit-Rate |
| (TSPEC)Minimum Data Rate, UL | Guaranteed-UL-Bit-Rate |
| (TSPEC)Mean Data Rate UL/DL | - |
| (TSPEC)Peak Data Rate, DL | Aggregate-Max-DL-Bit-Rate |
| (TSPEC)Peak Data Rate, UL | Aggregate-Max-UL-Bit-Rate |
+------------------------------+------------------------------+
Table 1: 802.11 - PMIPv6 QoS Parameter Mapping
3.1. Case A: MN Initiates QoS Request
During an MN flow setup that requires admission control in the 802.11
network, QoS parameters for the flow needs to be provisioned. This
procedure outlines the case where the MN is configured (e.g. in SIM)
to start the QoS signaling. In this case, the MN sends an ADDTS
request indicating the QoS required for the flow. The AP/WLC (MAG)
obtains the corresponding level of QoS to be granted to the flow by
PMIPv6 PBU/PBA sequence with QoS options with the LMA. Details of the
QoS provisioning for the flow are described below.
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+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
+-------------------------------------------------------------+
| [0] establish connection session to mobile network |
+-------------------------------------------------------------+
| | |
+-------------+ | |
|upper layer | | |
|notification | | |
+-+-+-+-+-+-+-+ | |
| | |
| ADDTS Request (TCLAS,TSPEC) | |
|---------------------------->| PBU(QoS options)[2] |
| [1] |-------------------->| QoS Policy
| |PBA (QoS option) [3] |<--------->
| ADDTS Response(TCLAS,TSPEC) |<--------------------|
|<----------------------------| |
| [4] | |
Figure 3: MN initiated QoS setup
[0] The MN has a best effort connectivity session as described in
section 2. This allows the MN to perform application level
signaling and setup.
[1] The trigger for MN to request QoS is an upper layer
notification. This may be the result of end-to-end application
signaling and setup procedures (e.g. SIP)
If the MN is configured to start QoS signaling, the MN sends an
ADDTS request with TSPEC and TCLAS identifying the flow for
which QoS is requested. The TSPECs for both uplink and downlink
in this request should contain the Minimum Data Rate and Peak
Data Rate .
[2] If there are sufficient resources at the AP/WLC to satisfy the
request, the MAG (AP/WLC sends a PBU with QoS options,
operational code ALLOCATE and Traffic Selector identifying the
flow. The Traffic selector is derived from the TCLAS to identify
the flow requesting QoS. 802.11 QoS parameters in TSPEC are
mapped to PMIPv6 parameters. The mapping of TCLAS and TSPEC
parameters to PMIPv6 is shown in Table 1.
[3] The LMA obtains the authorized QoS for the flow and responds to
the MAG with operational code set to RESPONSE. Mapping of PMIPv6
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parameters to 802.11 TSPEC and TCLAS is shown in Table 1.
In networks like 3GPP, the reserved bandwidth for flows are
accounted separately from the non-reserved session bandwidth.
The Traffic Selector identifies the flow for which the QoS
reservations are made.
[4] The AP/WLC (MAG) provisions the corresponding QoS and replies
with ADDTS Response containing authorized QoS in TSPEC and flow
identification in TSPEC.
The AP/WLC polices these flows according to the QoS
provisioning.
3.2. Case B: Network Initiates QoS Signaling (802.11aa based)
In some cases (e.g. LTE/SAE), the policy server in the network may be
configured to initiate the policy reservation request for a flow.
This use case illustrates how an MN and 802.11 network that support
802.11aa can provision QoS to flows of the MN that when the policy
server pushes the reservation request.
+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
+----------------------------------------------------------------+
| [0] establish connection session to mobile network |
+----------------------------------------------------------------+
| | |
| | | Policy update
| |UPN(QoS option)[2]|<-------------
| ADDTS Reserve Request |<-----------------| [1]
| (TCLAS, TSPEC)[3] | |
|<----------------------------| |
| ADDTS Reserve Response | |
| (TCLAS, TSPEC)[4] | |
|---------------------------->| |
| |UPA(QoS option)[5]|
| |----------------->|
| | |
Figure 4: Network initiated QoS setup with 802.11aa
[0] The MN sets up best effort connectivity session as described in
Case A. This allows the MN to perform application level
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signaling and setup.
[1] The policy server sends a QoS reservation request to the LMA.
This is usually sent in response to an application that requests
the policy server for higher QoS for some of its flows.
The LMA reserves resources for the flow requested.
[2] LMA sends PMIP UPN (Update Notification) to the MAG with QoS
parameters for the flow for which the LMA reserved resources in
step [1]. In UPN, the operational code in QoS option is set to
ALLOCATE and the Traffic Selector identifies the flow for QoS.
The LMA QoS parameters include Guaranteed-DL-Bit-
Rate/Guaranteed-UL-Bit-Rate and Aggregate-Max-DL-Bit-
Rate/Aggregate-Max-UL-Bit-Rate for the flow. In networks like
3GPP, the reserved bandwidth for flows are accounted separately
from the non-reserved session bandwidth.
[3] If there are sufficient resources to satisfy the request, the
AP/WLC (MAG) sends an ADDTS Reserve Request (802.11aa)
specifying the QoS reserved for the traffic stream including
TSPEC and TCLAS element mapped from PMIP QoS Traffic Selector to
identify the flow.
PMIPv6 parameters are mapped to TCLAS and TSPEC as shown in
Table 1.
If there are insufficient resources at the AP/WLC, the MAG will
not send and ADDTS message and will continue processing of step
[5].
[4] MN accepts the QoS reserved in the network and replies with
ADDTS Reserve Response.
[5] The MAG (AP/WLC) replies with UPA confirming the acceptance of
QoS options and operational code set to RESPONSE. The AP/WLC
police flows based on the new QoS.
If there are insufficient resources at the AP/WLC, the MAG sends
a response with UPA status code set to
CANNOT_MEET_QOS_SERVICE_REQUEST.
3.3. Case C: Hybrid (Network Initiated for PMIP, MN initiated in
802.11)
This use case outlines a scenario where an MN attaches to the 802.11
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and then obtains services in the mobile network. When the MN
attaches, PMIP signaling between the MAG and LMA establishes mobile
connection and related QoS. Subsequently, the MN starts an
application that requires dedicated bandwidth resources and signals
that using TSPEC/ADDTS request. The details of this sequence are
described below.
+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
| | |
+---------------------------------------------------------------+
| [0] establish connection session to mobile network |
+---------------------------------------------------------------+
| | | Policy update
| | UPN(QoS option)[2] |<--------------
| |<-------------------| [1]
+-------------+ | UPA(QoS option)[3] |
|upper layer | |------------------->|
|notification | | |
+-+-+-+-+-+-+-+ | |
| | |
| ADDTS Request(TSPEC)[4] | |
|------------------------>| |
| ADDTS Response(TSPEC)[5]| |
|<------------------------| |
| | |
Figure 5: Network initiated QoS setup with WMM
[0] The MN sets up best effort connectivity session as described in
Case A. This allows the MN to perform application level
signaling and setup.
[1] The policy server sends a QoS reservation request to the LMA.
This is usually sent in response to an application that requests
the policy server for higher QoS for some of its flows.
The LMA reserves resources for the flow requested.
[2] LMA sends PMIP UPN (Update Notification) to the MAG with QoS
option operational code set to ALLOCATE and QoS parameters for
which the LMA reserved resources in step [1]. In UPN, the
Traffic selector field in QoS Option identifies the flow for
QoS.
The LMA QoS parameters include Guaranteed-DL-Bit-
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Rate/Guaranteed-UL-Bit-Rate and Aggregate-Max-DL-Bit-
Rate/Aggregate-Max-UL-Bit-Rate for the flow. In networks like
3GPP, the reserved bandwidth for flows are accounted separately
from the non-reserved session bandwidth. This is indicated by
using the Traffic Selector in PMIPv6 QoS.
[3] If there are sufficient resources to satisfy the request, the
MAG (AP/WLC) replies with UPA confirming the acceptance of QoS
options and operation code set to RESPONSE. If there are
insufficient resources at the AP/WLC, the MAG may send a
response with UPA status code set to
CANNOT_MEET_QOS_SERVICE_REQUEST.
The AP/WLC can police flows based on the new QoS. However, the
AP/WLC does not initiate QoS reservation signaling on 802.11
because either it or the MN does not support 802.11aa.
[4] The trigger for the MN to request QoS is an upper layer
notification. This may be the result of end-to-end application
signaling and setup procedures (e.g. SIP)
The MN sends an ADDTS request with TSPEC and TCLAS identifying
the flow for which QoS is requested. The TSPECs for both uplink
and downlink in this request should contain the Minimum Data
Rate and Peak Data Rate. The MAG maps PMIPv6 parameters obtained
earlier as shown in Table 1.
If the MN supports only WMM QoS, TCLAS is not sent. The AP/WLC
may identify the flow based on connection signaling (e.g. 3GPP
23.402, WCS), most recent updates from PMIP QoS (i.e. that in
message [3] above), or some combination thereof.
[5] The AP/WLC (MAG) provisions the corresponding QoS and replies
with ADDTS Response containing authorized QoS in TSPEC.
The AP/WLC (MAG) may revise the offer to the MN based on PMIPv6
QoS reservation.
3.4. Case D: Network Initiated Release
QoS resources reserved for a session are released on completion of
the session. When the application session completes, the policy
server, or the MN may signal for the release of resources. In this
use case, the network initiates the release of QoS resources.
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+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
+-------------------------------------------------------------+
| [0] Establishment of application session |
| and reservation of QoS resources |
| |
| ( Session in progress) |
| |
| Release of application session |
+-------------------------------------------------------------+
| | | Policy update
| |UPN(QoSx,DE-ALLOC)[2]<--------------
| |<-------------------| [1]
| |UPA(QoSx,RESPONSE)[3]
| |------------------->|
| DELTS Request | |
| (TS INFO)[4] | |
|<-----------------------| |
| DELTS Response | |
| (TS INFO)[5] | |
|----------------------->| |
| | |
Figure 6: Network initiated QoS resource release
[0] The MN establishes and reserves QoS resources as in use cases A,
B or C.
When the application session terminates, the policy server
receives notification that the session has terminated.
[1] LMA receives a policy update indicating that QoS for flow (QoSx)
should be released. The LMA releases local resources associated
with the flow.
[2] LMA sends a UPN with QoS options - Traffic Selector field
identifying the flow for which QoS resources are to be released,
and operation code set to DE-ALLOCATE. No additional LMA QoS
parameters are sent.
[3] MAG replies with UPA confirming the acceptance and operation
code set to RESPONSE.
[4] AP/WLC (MAG) releases local QoS resources associated with the
flow. AP/WLC derives the corresponding 802.11 Traffic Stream
from the PMIPv6 Traffic Selector. The AP sends a DELTS Request
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with TS INFO identifying the reseravtion.
[5] MN sends DELTS Response confirming release.
Since the MN has completed the session, it may send a DELTS to
explicitly request release QoS resources at AP. If the AP and MN
are 802.11aa capable, the release of resources may also be
signaled to the MN.
3.5. Case E: MN Initiated Release
QoS resources reserved for a session are released on completion of
the session. When the application session completes, the policy
server, or the MN may signal for the release of resources. In this
use case, the network initiates the release of QoS resources.
+--------+
+----+ | AP/WLC | +-------+
| MN | | (MAG) | | LMA |
+-+--+ +---+----+ +---+---+
| | |
+-------------------------------------------------------------+
| [0] Establishment of application session |
| and reservation of QoS resources |
| |
| ( Session in progress) |
| |
| Release of application session |
+-------------------------------------------------------------+
| | |
| DELTS Request | |
| (TS INFO)[1] | |
|----------------------->| |
| DELTS Response | |
| (TS INFO)[2] | |
|<-----------------------| |
| |PBU(QoSx,DE-ALLOC)[3]
| |------------------->| Policy Update
| |PBA(QoSx,RESPONSE)[4]<------------>
| |<-------------------|
| | |
Figure 6: Network initiated QoS resource release
[0] The MN establishes and reserves QoS resources as in use cases A,
B or C.
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When the application session terminates, the MN prepares to
release QoS resources.
[1] MN releases its own internal resources and sends a DELTS Request
to the AP/WLC with TS (Traffic Stream) INFO.
[2] AP/WLC receives the DELTS request, releases local resources and
responds to MN with a DELTS response.
[3] AP/WLC (MAG) initiates a PBU with Traffic Selector constructed
from TCLAS and PMIPv6 QoS parameters from TSPEC (QoSx) as shown
in Table 1.
[4] LMA receives the PBU, releases local resources and informs
policy server. The LMA then responds with a PBA.
3.6. Service Guarantees in 802.11
The GBR - Guaranteed Bit Rate in mobile networks are used to request
and commit resources in the network for providing the bandwidth
requested. In 802.11 networks, a random backoff timer based on the
access class only provides priority access to a shared medium. These
mappings and recommendations allow the AP to schedule resources in a
fair manner based on subscribed QoS and application request/policy
server interaction.
However, there are no guaranteed or committed resources in the 802.11
network - only prioritization that gives better opportunity for
frames to compete for a shared medium.
It should also be noted that unlike mobile networks which inform the
MN about QoS for established or modified connections (bearers), there
is no means for an MN in 802.11 networks to find out the QoS that a
policy server requests to be granted. Thus, the application in MN
should make its determination to downgrade a request based on SDP and
media parameters to downgrade to a lower quality.
4. Mapping of QoS Parameters
This section outlines the handling of QoS parameters between 802.11
and PMIP QoS. 802.11 QoS reservations are made for an MN's data
frames. PMIP QoS provisioning on the other hand is for IP sessions
and flows. Parameters in PMIP QoS and 802.11 also need to be mapped
according to the recommendations below.
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4.1 Connection Mapping
TSPEC in 802.11 is used to reserve QoS for a traffic stream (MN MAC,
TS(Traffic Stream) id). The QoS reservation is for 802.11 frames
associated with an MN's MAC address. TCLAS element with Classifier 1
(TCP/UDP Parameters) should be used to identify a flow. The flow
definition should use the specification in [PMIP-QoS] Traffic
Selector. Thus, there is a one-to-one mapping between the TCLAS
defined flow and that in Traffic Selector.
When an 802.11 QoS reservation is complete, it is identified by a
Traffic Stream (TS) identifier. This corresponds to the flow in
PMIPv6 Traffic Selector, and identified in TCLAS. For releasing QoS
resources identified by a PMIPv6 Traffic selector, the AP/WLC uses
the above relationship to determine the corresponding TS identifier
to be sent in the DELTS request.
If the MN or AP/WLC is not able to convey TCLAS, the AP/WLC should
use out of band methods to determine the IP flow for which QoS is
requested. This includes correlation with connection signaling
protocols (e.g. 3GPP 23.402 WCS) and Traffic Selector in most recent
PMIP QoS updates.
4.2. QoS Class
Table 1 contains a mapping between Access Class (WMM AC) and 802.1D
in 802.11 frames, and DSCP in IP data packets. The table also
provides the mapping between Access Class (WMM AC) and DSCP for use
in 802.11 TSPEC and PMIP QoS reservations.
QCI DSCP 802.1D UP WMM AC Example Services
------------------------------------------------------------
1 EF 6(VO) 3 AC_VO conversational voice
2 EF 6(VO) 3 AC_VO conversational video
3 EF 6(VO) 3 AC_VO real-time gaming
4 AF41 5(VI) 2 AC_VI buffered streaming
5 AF31 4(CL) 2 AC_VI signaling
6 AF32 4(CL) 2 AC_VI buffered streaming
7 AF21 3(EE) 0 AC_BE interactive gaming
8 AF11 1(BE) 0 AC_BE web access
9 BE 0(BK) 1 AC_BK e-mail
Table 2: QoS Mapping between QCI/DSCP, 802.1D UP, WMM AC
The MN tags data packets with DSCP and 802.1D UP corresponding to the
application and the subscribed policy or authorization. The AP/WLC
polices sessions and flows based on these values and the QoS policy
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for the MN.
For QoS reservations, TSPEC use WMM AC values and PMIP QoS uses
corresponding DSCP values in Traffic Selector. 802.11 QoS Access
Class AC_VO, AC_VI are used for QoS reservations. AC_BE, AC_BK should
not be used in reservations.
4.3. Bandwidth
There are bandwidth parameters that need to be mapped for admission
controlled flows and others for non-admission controlled flows.
Non-Admission Controlled Flows:
Flows and sessions that do not need QoS reservation have no need
for equivalent mapping for 802.11. These sessions and flows are
policed by the AP/WLC to ensure that QoS policy obtained initially
(during MN authorization) or dynamically over PMIP QoS is not
exceeded by the MN.
All connection sessions of the MN should not in total exceed Per-
MN-Agg-Max-DL-Bit-Rate and Per-MN-Agg-Max-UL-Bit-Rate in the
downlink and uplink directions respectively. The non-admission
controlled flows of a single connectivity session of an MN should
not exceed Per-Session-Agg-Max-DL-Bit-Rate and Per-Session-Agg-
Max-UL-Bit-Rate in the downlink and uplink directions
respectively.
Admission Controlled Flows:
For flows that require reservation, the 802.11 Minimum Data Rate
should be equal to Guaranteed Bit Rate (GBR). If the MN requests
Minimum Data Rate in ADDTS greater than GBR, then AP/WLC should
reject the admission request in ADDTS Response.
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+-------------------------+------------------------------+
| MN <--> AP/WLC(802.11) | AP/WLC(MAG) <--> LMA PMIPv6 |
+-------------------------+------------------------------+
| Minimum Data Rate, DL | Guaranteed-DL-Bit-Rate |
| Minimum Data Rate, UL | Guaranteed-UL-Bit-Rate |
| Mean Data Rate UL/DL | [a] |
| Peak Data Rate, DL | Aggregate-Max-DL-Bit-Rate |
| Peak Data Rate, UL | Aggregate-Max-UL-Bit-Rate |
+-------------------------+------------------------------+
NOTE[a] AP/WLC may derive Mean Data Rate from Minimum and Maximum
Data Rates. There is no equivalent parameter in PMIP QoS.
Table 3: Bandwidth Parameters for Admission Controlled Flows
During the QoS reservation procedure, if the MN requests Minimum
Data Rate, or other parameters in excess of values authorized in
PMIP QoS, the AP/WLC should deny the request in ADDTS Response.
Bandwidth of admission controlled flows are policed according to
the mappings in Table 2.
4.4. Preemption Priority
Mobile networks with resource reservation configure ARP (Allocation
Retention Priority) during authorization and it is obtained in [PMIP
QoS]. There is no corresponding configuration in 802.11 QoS. However,
the AP/WLC may use ARP to determine priority during call setup and
vulnerability to release of reserved QoS resources.
Parameter Allocation-Retention-Priority and sub fields of Priority,
Preemption-Capability and Preemption-Vulnerability are used as
defined in [PMIP-QoS].
When a new ADDTS request for reservation of QoS resources arrives, if
there is sufficient free resources, the AP/WLC proceeds to allocate
it. If there are insufficient resources, the AP/WLC may preempt
existing calls based on the Preemption-Capability of the new call and
Preemption-Vulnerability of established calls.
If the AP/WLC determines that an established flow with reserved
resources should be released, the AP/WLC should inform the MN using
ADDTS (802.11aa) and signal the LMA with a revised QoS reservation in
PBU/PBA.
5. Security Considerations
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This document describes mapping of 3GPP QoS profile and parameters to
IEEE 802.11 QoS 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-11, Feb 2014.
[WMM 1.2.0] Wi-Fi Multimedia Technical Specification (with WMM-Power
Save and WMM-Admission Control) Version 1.2.0
[802.11aa] Wireless LAN Medium Access Control (MAC) and Physical
Layer (PHY) Specification, Amendment 2: MAC Enhancements
for Robust Audio Video Streaming, IEEE 802.11aa-2012.
[802.11-2012] 802.11-2012 - IEEE Standard for Information technology-
-Telecommunications and information exchange between
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systems Local and metropolitan area networks--Specific
requirements Part 11: Wireless LAN Medium Access Control
(MAC) and Physical Layer (PHY) Specifications
[GSMA-IR34]Inter-Service Provider Backbone Guidelines 5.0, 22
December 2010
[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
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).
[TS23.402] Architecture Enhancements for non-3GPP accesses(Release
12), 3GPP TS 23.402, V12.2.0 (2013-09).
[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).
[TS29.273] 3GPP EPS AAA interfaces(Release 12), 3GPP TS 29.273
v12.1.0 (2013-09)
Authors' Addresses
John Kaippallimalil
5340 Legacy Drive, Suite 175
Plano, Texas 75024
E-Mail: john.kaippallimalil@huawei.com
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Rajesh Pazhyannur
170 West Tasman Drive
San Jose, CA 95134
E-Mail: rpazhyan@cisco.com
Parviz Yegani
1194 North Mathilda Ave.
Sunnyvale, CA 94089-1206
E-Mail: pyegani@juniper.net
Appendix A: QoS in 802.11, PMIPv6 and 3GPP Networks
A.1. QoS in IEEE 802.11 Networks
IEEE 802.11-2012 [802.11-2012] provides an enhancement of the MAC
layer in 802.11 networks to support QoS--EDCA (Enhanced Distributed
Channel Access). EDCA uses a contention based channel access method
to provide differentiated, distributed access using eight different
UPs (User Priorities). EDCA also defines four access categories (AC)
that provide support for the delivery of traffic. In EDCA, the random
back-off timer and arbitration inter-frame space is adjusted
according to the QoS priority. Frames with higher priority AC have
shorter random back-off timers and arbitration inter-frame spaces.
Thus, there is a better chance for higher priority frames to be
transmitted. The Wi-Fi Alliance has created a specification referred
to as WMM (Wi-Fi Multimedia) based on above.
The MN uses ADDTS (Add Traffic Specs) to setup QoS for a traffic
stream between itself and the AP, and DELTS to delete that stream. In
WMM [WMM 1.2.0], the AP advertises if admission control is mandatory
for an access class. Admission control for best effort or background
access classes is not recommended. The Wi-Fi Alliance has created a
specification referred to as WMM-AC (Wi-Fi Multimedia Admission
Control) based on the above.
A.2. QoS in PMIPv6 Mobility domain
[PMIP-QoS] defines a mobility option that can be used by the mobility
entities in the Proxy Mobile IPv6 domain to exchange Quality of
Service parameters associated with an MN's IP flows. Using the QoS
option, the local mobility anchor and the mobile access gateway can
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exchange available QoS attributes and associated values. QoS
attributes include node and mobile session Aggregate Maximum Bit Rate
(AMBR) for upstream and downstream, Guaranteed Bit Rate (GBR) for
upstream and downstream, Maximum Bit Rate (MBR) for upstream and
downstream and the Allocation Retention Priority (ARP).
[PMIP-QoS] does not explicitly describe how the QoS signaling and QoS
sub-options map into corresponding signaling and parameters in the
802.11 access network. This mapping and the procedures in the 802.11
network to setup procedures are the focus of this document. The end-
to-end flow spanning 802.11 access and PMIPv6 domain and the QoS
parameters in both segments are described in subsequent sections.
A.3. 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 MN (host)
and gateway [TS23.402]. 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].
The use cases in subsequent sections use 3GPP policy along with PMIP
QoS for provisioning of QoS in the 802.11 network. However, this is
exemplary and alternative policy architectures may be used in
practice.
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