Internet DRAFT - draft-ietf-netext-pmip-qos-wifi
draft-ietf-netext-pmip-qos-wifi
IETF J. Kaippallimalil
Internet-Draft Huawei
Intended status: Informational R. Pazhyannur
Expires: October 12, 2015 Cisco
P. Yegani
Juniper
April 10, 2015
Mapping PMIPv6 QoS Procedures with WLAN QoS Procedures
draft-ietf-netext-pmip-qos-wifi-08
Abstract
This document provides guidelines for achieving end to end Quality-
of-Service (QoS) in a Proxy Mobile IPv6 (PMIPv6) domain where the
access network is based on IEEE 802.11. RFC 7222 describes QoS
negotiation between a Mobility Access Gateway (MAG) and Local
Mobility Anchor (LMA) in a PMIPv6 mobility domain. The negotiated
QoS parameters can be used for QoS policing and marking of packets to
enforce QoS differentiation on the path between the MAG and LMA.
IEEE 802.11-2012, Wi-Fi Multimedia - Admission Control (WMM-AC)
describes methods for QoS negotiation between a Wi-Fi Station (MN in
PMIPv6 terminology) and an Access Point. This document provides a
mapping between the above two sets of QoS procedures and the
associated QoS parameters. This document is intended to be used as a
companion document to RFC 7222 to enable implementation of end to end
QoS.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 12, 2015.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5
2. Overview of IEEE 802.11 QoS . . . . . . . . . . . . . . . . . 7
3. Mapping QoS Procedures between IEEE 802.11 and PMIPv6 . . . . 7
3.1. MN Initiated QoS Service Request . . . . . . . . . . . . 8
3.1.1. MN Initiated QoS Reservation Request . . . . . . . . 8
3.1.2. MN Initiated QoS De-allocation Request . . . . . . . 10
3.2. LMA Initiated QoS Service Request . . . . . . . . . . . . 12
3.2.1. LMA Initiated QoS Reservation Request . . . . . . . . 12
3.2.2. Discussion on QoS Request Handling with IEEE 802.11aa 13
3.2.3. LMA Initiated QoS De-allocation Request . . . . . . . 13
4. Mapping between IEEE 802.11 QoS and PMIPv6 QoS Parameters . . 15
4.1. Connection Parameters . . . . . . . . . . . . . . . . . . 15
4.2. QoS Class . . . . . . . . . . . . . . . . . . . . . . . . 16
4.3. Bandwidth . . . . . . . . . . . . . . . . . . . . . . . . 17
5. Security Considerations . . . . . . . . . . . . . . . . . . . 18
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. LMA Initiated QoS Service Flow with IEEE 802.11aa . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22
1. Introduction
PMIPv6 QoS [1] describes an access network independent way to
negotiate Quality-of-Service (QoS) for Proxy Mobile IPv6 (PMIPv6)
mobility sessions. IEEE 802.11, Wi-Fi Multimedia (WMM), Wi-Fi
Multimedia - Admission Control (WMM-AC) describe ways to provide QoS
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for Wi-Fi traffic between the Wi-Fi Station (STA) and Access Point
(AP). This document describes how QoS can be implemented in a
network where the access network is based on IEEE 802.11 (Wi-Fi). It
requires a mapping between QoS procedures and information elements in
two segments 1) Wi-Fi segment and 2) PMIPv6 segment (see Figure 1).
The recommendations here allow for dynamic QoS policy information per
Mobile Node (MN) and session to be configured by the IEEE 802.11
access network. PMIPv6 QoS signaling between Mobility Access Gateway
(MAG) and Local Mobility Anchor (LMA) provisions the per MN QoS
policies in the MAG. Further details on policy configuration and PCF
(Policy Control Function) can be found in [1], Section 6.1. In the
IEEE 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 |
+--+--+ +---+---+
| |
| |
+----+ +--+--------+ +---+---+
| | IEEE 802.11, WMM-AC |+-++ +---+| PMIPv6 | |
| MN <---------------------->|AP+--+MAG|<==========> LMA |
| | (ADDTS, DELTS) |+--+ +---+| QoS | |
+----+ +-----------+ +-------+
Figure 1: End-to-End QoS in Networks with IEEE 802.11 Access
MN and Access Point AP use IEEE 802.11 QoS mechanisms to setup QoS
flows in the Wi-Fi segment. The MAG and LMA setup QoS flows using
PMIPv6 QoS procedures. The protocols and mechanisms between AP and
MAG are out of scope of this document. Some implementations may have
AP and MAG in the same network node. However, this document does not
exclude various deployments including those where AP and WLC are
separate nodes, or the MAG control and data planes are separate.
The recommendations in this document use IEEE 802.11 QoS and PMIPv6
QoS [1] mechanisms. State machines for QoS policy setup in IEEE
802.11 and PMIPv6 operate differently. Guidelines for installing QoS
in the MN using 802.11 and PMIPv6 segments, and for mapping
parameters between them are outlined below.
- Procedure Mapping:
PMIPv6 [RFC 7222] defined procedures for QoS setup maybe
triggered by the LMA or MAG. IEEE 802.11 QoS setup on the other
hand is always triggered by the MN (IEEE 802.11 QSTA). The end-
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to-end QoS setup across these network segments should accommodate
both network triggered and end-user triggered QoS.
- Parameter Mapping:
There is no systematic method of mapping of specific parameters
between PMIPv6 QoS parameters and IEEE 802.11 QoS. For example,
parameters like Allocation Retention Priority (ARP) in PMIPv6 QoS
have no equivalent in IEEE 802.11.
The primary emphasis of this specification is to handle the
interworking between WMM-AC signaling/procedures and PMIPv6 QoS
signaling/procedures. When the client does not support WMM-AC, then
the AP/MAG uses the connection mapping in Table 2 and DSCP to AC
mapping as shown in Table 3.
The rest of the document is organized as follows. Section 2 provides
an overview of IEEE 802.11 QoS. Section 3 describes a mapping of QoS
signaling procedures between IEEE 802.11 and PMIPv6. The mapping of
parameters between IEEE 802.11 and PMIPv6 QoS is described in
Section 4.
1.1. Abbreviations
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AAA Authentication Authorization Accounting
AC Access Category
ADDTS ADD Traffic Stream
AIFS Arbitration Inter-Frame Space
ALG Application Layer Gateway
AMBR Aggregate Maximum Bit Rate
ARP Allocation and Retention Priority
AP Access Point
CW Contention Window
DELTS DELete Traffic Stream
DL DownLink
DSCP Differentiated Services Code Point
DPI Deep Packet Inspection
EDCA Enhanced Distributed Channel Access
EPC Evolved Packet Core
GBR Guaranteed Bit Rate
MAC Media Access Control
MAG Mobility Access Gateway
MBR Maximum Bit Rate
MN Mobile Node
MSDU Media Access Control Service Data Unit
PBA Proxy Binding Acknowledgement
PBU Proxy Binding Update
PCF Policy Control Function
PHY Physical Layer
QCI QoS Class Identifier
QoS Quality of Service
QSTA QoS Station
SIP Session Initiation Protocol
STA Station
TC Traffic Class
TCLAS Type Classification
TCP Transmission Control Protocol
TS Traffic Stream
TSPEC Traffic Conditioning Specification
UDP User Datagram Protocol
UL UpLink
UP User Priority
WLAN Wireless Local Area Network
WLC Wireless Controller
WMM Wi-Fi MultiMedia
WMM-AC Wi-Fi MultiMedia Admission Control
1.2. Definitions
Peak Data Rate
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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 [4]. IP packet including header is included in the
data rate.
TSPECs for both uplink and downlink may contain Peak Data Rate.
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 [4]. IP packet
including header is included in the data rate.
TSPECs for both uplink and downlink must contain the Mean Data
Rate.
Mimimum 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 [4]. IP packet including header is included in the
data rate.
Minimum Data Rate is not used in QoS provisioning described here.
QCI
Quality of Service Identifier (QCI) is a scalar parameter that
points to standardized characteristics of QoS as opposed to
signaling separate parameters for resource type, priority, delay
and loss [8].
STA
A station (STA) is a device that has the capability to use the
802.11 protocol. For example, a station maybe a laptop, a
desktop PC, access point or WiFi phone [3].
An STA that implements the QoS facility is a QoS Station (QSTA)
[3].
TSPEC
The TSPEC element in IEEE 802.11 contains the set of parameters
that define the characteristics and QoS expectations of a traffic
flow [3].
TCLAS
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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) [3].
2. Overview of IEEE 802.11 QoS
IEEE 802.11-2012 defines a way of providing prioritized access for
different traffic classes (video, voice, etc) by a mechanism called
EDCA (Enhanced Distributed Channel Access). The levels of priority
in EDCA are called access categories (ACs) and there are four levels
(in decreasing order of priority): Voice, Video, Best-Effort,
Background. The prioritized access is achieved by using access
category specific values for contention window (CW) and arbitration
inter frame space (AIFS). (Higher priority categories have smaller
values for minimum and maximum CW and AIFS).
A subset of the QoS mechanisms is defined in WMM - a Wi-Fi Alliance
certification of support for a set of features from an 802.11e draft
(now part of IEEE 802.11). This certification is for both clients
and APs, and certifies the operation of WMM. WMM is primarily the
implementation of the EDCA component of 802.11e. WMM uses the 802.1P
classification scheme developed by the IEEE (which is now a part of
the 802.1D specification). The 802.1P classification scheme has
eight priorities, which WMM maps to four access categories: AC_BK,
AC_BE, AC_VI, and AC_VO. The lack of support in WMM for the TCLAS
(used in identifying an IP flow) has an impact on the QoS
provisioning. The impact is described in Chapters 3 and 4 for WMM
based QoS provisioning.
IEEE 802.11 defines the way a (non-AP) STA can request QoS to be
reserved for an access category. Correspondingly, the AP can
determine whether to admit or deny the request depending on the
available resources. Further, the AP may require that Admission
Control is mandatory for an access category. In such a case, the STA
is expected to use the AC only after being successfully admitted.
WMM-AC is a Wi-Fi Alliance certification of support for admission
control based on a set of features in IEEE 802.11.
The QoS signaling in IEEE 802.11-2012 is initiated by the (non-AP)
STA (by sending an ADDTS request). This specification references
procedures in IEEE 802.11-2012, WMM and WMM-AC.
3. Mapping QoS Procedures between IEEE 802.11 and PMIPv6
There are two main types of interaction possible to provision QoS for
flows that require admission control - one 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 PMIPv6 QoS
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request. In the second scenario, the LMA can push the QoS
configuration to the MAG. However, there are no standards defined
way for the AP to initiate a QoS service request to the MN.
Recommendations to setup QoS in both these cases are described in
this section.
3.1. MN Initiated QoS Service Request
3.1.1. MN Initiated QoS Reservation Request
This procedure outlines the case where the MN is configured to start
the QoS signaling. In this case, the MN sends an ADDTS request
indicating the QoS required for the flow. The AP/MAG obtains the
corresponding level of QoS to be granted to the flow by PMIPv6 PBU/
PBA sequence with QoS options exchanged with the LMA. Details of the
QoS provisioning for the flow are described below.
+-----------+
+----+ |+--+ +---+| +-------+
| MN | ||AP| |MAG|| | LMA |
+-+--+ ++-++--+-+-++ +---+---+
| | | |
+-------------------------------------------------------------+
| (0) establish connection session to mobile network |
+-------------------------------------------------------------+
| | | |
+-------------+ | | |
|upper layer | | | |
|notification | | | |
+-+-+-+-+-+-+-+ | | |
| | | |
| ADDTS Request(TCLAS(opt),TSPEC),AC| |
|---------------------------->| | |
| (1) |---->|PBU(QoS options)(2)|
| | |------------------>|
| | | | Policy
| | |PBA(QoS option)(3) |<----->
| | |<------------------|
| |<----| |
|ADDTS Response(TCLAS(opt),TSPEC),AC| |
|<----------------------------| | |
| (4) | |
Figure 2: MN initiated QoS service request
In this use case shown in Figure 2, the MN initiates the QoS service
request.
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(0) The MN establishes a connectivity session as described in [1],
Section 3.1, MAG-initiated QoS service request, steps 1-4. At
this point, a connection with PMIPv6 tunnel is established to the
LMA. This allows the MN to start application level signaling.
(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 [10]).
Since the MN is configured to start QoS signaling, it sends an
ADDTS request with TSPEC and TCLAS identifying the flow for which
QoS is requested.
It should be noted that WMM-AC specifications do not contain
TCLAS. When TCLAS is not present, there is no direct way to
derive flow specific attributes like Traffic Selector in PMIPv6.
In this case functionality to derive IP flow details from
information in upper layer protocols (e.g., SIP [10]) and
associate to subsequent QoS request may be used. This is not
described further here, but it maybe functionality in an
Application Layer Gateway (ALG) or Deep Packet Inspection (DPI).
It should be noted that an ALG or DPI can increase the complexity
of the AP/MAG implementation and affect its scalability. If no
TCLAS is derived, the reservation applies to all flows of the MN
(not desired). Parameter mapping in this case is shown in
Table 2.
(2) If there are sufficient resources at the AP/WLC to satisfy the
request, the MAG 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. IEEE 802.11 QoS parameters in TSPEC are mapped
to PMIPv6 parameters. The mapping of TCLAS to PMIPv6 is shown in
Table 1. TSPEC parameter mapping is shown in Table 4.
If TCLAS is not present (when WMM-AC is used), TCLAS maybe
derived from information in upper layer protocols (as described
in step 1) and populated in Traffic Selector. If TCLAS cannot be
derived, the Traffic Selector field is not included in the QoS
options.
(3) The LMA obtains the authorized QoS for the flow and responds to
the MAG with operational code set to RESPONSE. Mapping of PMIPv6
to IEEE 802.11 TCLAS is shown in Table 1, TSPEC parameters in
Table 4.
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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.
If the LMA offers downgraded QoS values to the MAG, it should
send a PBU to LMA with operational code set to DE-ALLOCATE (the
LMA would respond with PBA to confirm completion of the request).
(4) The AP/MAG provisions the corresponding QoS and replies with
ADDTS Response containing authorized QoS in TSPEC and flow
identification in TSPEC and ResultCode set to SUCCESS.
The AP polices these flows according to the QoS provisioning.
If in step (3), the LMA sends a downgraded QoS or a PBA message
with status code CANNOT_MEET_QOS_SERVICE_REQUEST (179), then the
AP should respond to the MN with ADDTS Response and ResultCode
set as follows:
- for downgraded QoS from LMA, ResultCode is set to
REJECTED_WITH_SUGGESTED_CHANGES. Downgraded QoS values from
LMA are mapped to TSPEC as per Table 4. This is still a
rejection, but the MN may revise the QoS to a lower level and
repeat this sequence if the application can adapt.
- if LMA cannot meet QoS service request, ResultCode is set to
TCLAS_RESOURCES_EXHAUSTED.
REJECTED_WITH_SUGGESTED_CHANGES and TCLAS_RESOURCES_EXHAUSTED
results in the rejection of the QoS reservation, but does not
cause the removal of the session itself.
3.1.2. MN Initiated QoS De-allocation Request
QoS resources reserved for a session are released on completion of
the session. When the application session completes, the LMA, or the
MN may signal for the release of resources. In this use case shown
in Figure 3, the MN initiates the release of QoS resources.
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+-----------+
+----+ |+--+ +---+| +-------+
| MN | ||AP| |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(QoS,DE-ALLOC)(3)|
| | |------------------->|Policy
| | | |<---->
| | | |Update
| | |PBA(QoS,RESPONSE)(4)|
| | |<-------------------|
| | | |
Figure 3: MN Initiated QoS resource release
(0) The MN establishes and reserves QoS resources. 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 with TS (Traffic Stream) INFO.
(2) AP receives the DELTS request, releases local resources and
responds to MN with a DELTS response.
(3) MAG initiates a PBU, operational code set to DE-ALLOCATE and with
Traffic Selector constructed from TCLAS and PMIPv6 QoS parameters
from TSPEC.
When TLCAS is not present, the MAG should de-allocate all flows
with the same access category (AC) as indicated in the DELTS
Request. In the typical case, if the client does not support
TCLAS and only MN initiated QoS Service requests are supported,
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then the MAG will have at most one QoS Service request per access
category (AC).
(4) LMA receives the PBU and releases local resources. The LMA then
responds with a PBA.
It should be noted that steps 3 and 4 can proceed independently of
the DELTS Response (step 2).
3.2. LMA Initiated QoS Service Request
3.2.1. LMA Initiated QoS Reservation Request
This section describes the case when the QoS service request is
initiated by the LMA. For example an application such as voice may
request the network to initiate configuration of additional QoS
policy as in [8], Section 7.4.2. In the current WLAN specifications,
there are no standards defined way for the AP to initiate a QoS
service request to the MN. As a result, when the MAG receives a QoS
request from the LMA, it does not have any standard mechanisms to
initiate any QoS requests to the MN over the access network. Given
this, the PMIPv6 QoS service requests and any potential WLAN service
requests (such as described in Section 3.1) are handled
asynchronously.
The PMIPv6 QoS service requests and WLAN QoS service request could
still be coordinated to provide an end to end QoS. If the MAG
receives a UPN request from the LMA to reserve QoS resources for
which it has no corresponding QoS request from the MN, the MAG may in
consultation with the AP provision a policy that can grant a
subsequent QoS request from the MN. If the MN initiates QoS
procedures after the completion of PMIPv6 QoS procedures the AP/MAG
can ensure consistency between the QoS resources in the access
network and QoS resources between the MAG and LMA.
For example, if the MN is requesting a mean data rate of x Mbps, the
AP and MAG can ensure that the rate can be supported on the network
between MAG-LMA based on previous PMIPv6 QoS procedures. If the MN
subsequently requests for data rates of x Mbps or less, the AP can
accept it based on the earlier PMIPv6 QoS provisioning. For the case
where there is a mismatch, i.e., the network does not support the x
Mbps, then either the MAG should re-negotiate the QoS resource and
ask for increased QoS resources or the AP should reject the QoS
request.
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3.2.2. Discussion on QoS Request Handling with IEEE 802.11aa
The network initiated QoS service request scenario poses some
challenges outlined here. IEEE 802.11-2012 does not provide any
mechanisms for the AP to initiate a QoS request. As a result, the
AP/MAG cannot explicitly make any reservations in response to a QoS
reservation request made using UPN. IEEE 802.11aa [5](which is an
amendment to IEEE 802.11-2012) has a mechanism that enables the AP to
ask the client to reserve QoS for a traffic stream. It does this via
the ADDTS Reserve Request. The ADDTS Reserve Request contains a
TSPEC, an optional TCLAS, and a mandatory Stream Identifier. The
specification does not describe how the AP would obtain such a stream
identifier. As a result, there needs to be a new higher layer
protocol defined understood by the MN and AP that provides a common
stream identifier to both ends. Alternately, the 802.11aa
specification could be modified to make the usage optional. When (or
if) the Stream Identifier is made optional, the TCLAS can provide
information about the traffic stream.
Appendix A outlines a protocol sequence with PMIPv6 UPN/UPA if the
above 802.11aa issues can be resolved.
3.2.3. LMA Initiated QoS De-allocation Request
QoS resources reserved for a session are released on completion of
the session. When the application session completes, the LMA, 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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+-----------+
+----+ |+--+ +---+| +-------+
| MN | ||AP| |MAG|| | LMA |
+-+--+ ++-++--+-+-++ +---+---+
| | | |
+-------------------------------------------------------------+
| Establishment of application session |
| and reservation of QoS resources |
| |
| ( Session in progress) |
| |
| Release of application session |
+-------------------------------------------------------------+
| | | | Policy
| | | |<------
| | |UPN(QoS,DE-ALLOC) |
| | |<------------------|
| |<----| (1) |
| |---->|UPA(QoS,RESPONSE) |
| | |------------------>|
| | | (2) |
| | | |
| DELTS Request (TS INFO)(3) | | |
|<----------------------------| | |
| DELTS Response (TS INFO)(4) | | |
|---------------------------->| | |
| | | |
Figure 4: LMA initiated QoS resource release
In this use case shown in Figure 4, the network initiates the release
of QoS resources. When the application session terminates, the LMA
receives notification that the session has terminated. The LMA
releases local QoS resources associated with the flow and initiates
signaling to release QoS resources in the network.
(1) LMA sends a UPN with QoS options 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.
(2) MAG replies with UPA confirming the acceptance and operation code
set to RESPONSE.
(3) AP/WLC (MAG) releases local QoS resources associated with the
flow. The AP derives the corresponding Access Category from the
Traffic Class (TC) field provided in the QoS option. In
addition, if the AP supports TCLAS and the QoS option contains a
Traffic Selector field, then the AP SHALL map the Traffic
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Selector into a TCLAS element. In the case where the AP does not
support TCLAS (for example a WMM-AC compliant AP) then the AP
SHALL only use the Access Category. The AP sends a DELTS Request
with TS INFO identifying the reservation.
(4) MN sends DELTS Response confirming release.
It should be noted that steps 3 and 4 can proceed independently of
the UPA (step 2).
4. Mapping between IEEE 802.11 QoS and PMIPv6 QoS Parameters
4.1. Connection Parameters
TSPEC in IEEE 802.11 is used to reserve QoS for a traffic stream (MN
MAC, TS(Traffic Stream) id). The IEEE 802.11 QoS reservation is for
IEEE 802.11 frames associated with an MN's MAC address.
The TCLAS element with Classifier 1 (TCP/UDP Parameters) is used to
identify a PMIPv6 QoS flow. We should note that WMM-AC procedures do
not support TCLAS. When TCLAS is present, a one-to-one mapping
between the TCLAS defined flow and the Traffic Selector is given
below.
QoS reservations in 802.11 are made for a traffic stream (identified
in TCLAS) and correspond to PMIPv6 QoS session parameters (identified
by Traffic Selector). PMIPv6 QoS [1] specifies that when QoS-
Traffic-Selector is included along with the per-session bandwidth
attributes described in Section 4.3 below, the attributes apply at a
per-session level.
+--------------------------------+----------------------------+
| MN <--> AP(IEEE 802.11) | MAG <--> LMA (PMIPv6) |
+--------------------------------+----------------------------+
| (TCLAS Classifier 1)TCP/UDP IP | Traffic Selector (IP flow) |
| (TCLAS Classifier 1) DSCP | Traffic Class (TC) |
+--------------------------------+----------------------------+
Table 1: IEEE 802.11 - PMIPv6 QoS Connection mapping
If the MN or AP is not able to convey flow parameters in TCLAS, the
QoS reservation request in 802.11 are derived as shown in Table 2.
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+------------------------------+--------------------------+
| MN <--> AP(WMM) | MAG <--> LMA (PMIPv6) |
+------------------------------+--------------------------+
| (no IP flow parameter/TCLAS) | (a) applies to all flows |
| | (b) derived out-of-band |
| | |
| User Priority (802.1D) | Traffic Class (TC) |
| | (derived using Table 3) |
+------------------------------+--------------------------+
Table 2: WMM - PMIPv6 QoS Connection mapping
When WMM [4] is used, and TCLAS is not present to specify IP flow,
one of two options apply for the MAG - LMA (PMIPv6) segment:
(a) Bandwidth parameters described in Section 4.3 apply to all flows
of the MN. This is not a preferred mode of operation if the LMA
performs reservation for a single flow, e.g. a voice flow
identified by an IP 5-tuple.
(b) The IP flow for which the MN requests reservation is derived out-
of-band. For example, the AP/MAG observes application level
signaling (e.g. SIP [10]) or session level signaling (e.g. 3GPP
WLCP (WLAN Control Protocol) [7])and associates subsequent ADDTS
request using heuristics and then derives the IP flow/Traffic
Selector field.
4.2. QoS Class
Table 3 contains a mapping between Access Class (WMM AC) and 802.1D
User Priority (UP) tag in IEEE 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 IEEE 802.11 TSPEC and PMIPv6 QoS
(Traffic Class). Mapping of QCI to DSCP uses the tables in [6].
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+-----+------+-----------+---------+----------------------+
| 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 3: QoS Mapping between QCI/DSCP, 802.1D UP, WMM AC
The MN tags all data packets with DSCP and 802.1D UP corresponding to
the application and the subscribed policy or authorization. The AP
polices sessions and flows based on the configured QoS policy values
for the MN.
For QoS reservations, TSPEC uses WMM AC values and PMIPv6 QoS uses
corresponding DSCP values in Traffic Class (TC). IEEE 802.11 QoS
Access Class AC_VO, AC_VI are used for QoS reservations. AC_BE,
AC_BK should not be used in reservations.
When WMM-AC specifications that do not contain TCLAS are used, it is
only possible to have one reservation per Traffic Class / access
category (AC). PMIPv6 QoS will not contain any flow specific
attributes like Traffic Selector.
4.3. Bandwidth
Bandwidth parameters that need to be mapped between IEEE 802.11 and
PMIPv6 QoS are shown in Table 4.
+-------------------------+---------------------------+
| MN <--> AP(IEEE 802.11) | MAG <--> LMA (PMIPv6) |
+-------------------------+---------------------------+
| Mean Data Rate, DL | Guaranteed-DL-Bit-Rate |
| Mean Data Rate, UL | Guaranteed-UL-Bit-Rate |
| Peak Data Rate, DL | Aggregate-Max-DL-Bit-Rate |
| Peak Data Rate, UL | Aggregate-Max-UL-Bit-Rate |
+-------------------------+---------------------------+
Table 4: Bandwidth Parameters for Admission Controlled Flows
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In PMIPv6 QoS [1], services using a sending rate smaller than or
equal to Guaranteed Bit Rate (GBR) can in general assume that
congestion related packet drops will not occur [8]. If the rate
offered by the service exceeds this threshold, there are no
guarantees provided. IEEE 802.11 radio networks do not offer such a
guarantee, but [4] notes that the application (service) requirements
are captured in TSPEC by the MSDU (MAC Service Data Unit) and Mean
Data Rate. The TSPEC should contain Mean Data Rate and it is
recommended that it be mapped to the GBR parameters, Guaranteed-DL-
Bit-Rate and Guaranteed-UL-Bit-Rate in PMIPv6 QoS [1].
IEEE 802.11 TSPEC requests do not require all fields to be completed.
[4] specifies a list of TSPEC parameters that are required in the
specification. Peak Data Rate is not required in WMM, however for
MNs and APs that are capable of specifying the Peak Data Rate, it
should be mapped to MBR (Maximum Bit Rate) in PMIPv6 QoS. The AP
should use the MBR parameters, Aggregate-Max-DL-Bit-Rate and
Aggregate-Max-UL-Bit-Rate to police these flows on the backhaul
segment between MAG and LMA.
During the QoS reservation procedure, if the MN requests Mean Data
Rate, or Peak Data Rate in excess of values authorized in PMIPv6 QoS,
the AP should deny the request in ADDTS Response. The AP may set the
reject cause code to REJECTED_WITH_SUGGESTED_CHANGES and send a
revised TSPEC with Mean Data Rate and Peak Data Rate set to
acceptable GBR and MBR respectively in PMIPv6 QoS.
5. Security Considerations
This document describes mapping of PMIPv6 QoS parameters to IEEE
802.11 QoS parameters. Thus, the security in the WLAN and PMIPv6
signaling segments and the functional entities that map the two
protocols need to be considered. 802.11-2012 [3] provides the means
to secure management frames that are used for ADDTS and DELTS.
PMIPv6 [9] specification recommends using IPSec and IKEv2 to secure
protocol messages. The security of the node(s) that implement the
QoS mapping functionality should be considered in actual deployments.
The QoS mappings themselves do not introduce additional security
concerns.
6. IANA Considerations
No IANA assignment of parameters are required.
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7. Acknowledgements
The authors thank the NetExt Working Group for the valuable feedback
to different versions of this specification. In particular, the
authors wish to thank Sri Gundavelli, Rajeev, Koodli, Georgios
Karagianis, Kent Leung, Marco Liebsch, Basavaraj Patil, Pierrick
Seite, Hidetoshi Yokota for their suggestions and valuable input.
The authors also thank George Calcev, Mirko Schramm, Mazin Shalash
and Marco Spini for detailed input on parameters and scheduling in
IEEE 802.11 and 3GPP radio networks.
8. References
8.1. Normative References
[1] Liebsch, M., Seite, P., Yokota, H., Korhonen, J., and S.
Gundavelli, "Quality-of-Service Option for Proxy Mobile
IPv6", RFC 7222, May 2014.
[2] Krishnan, S., Gundavelli, S., Liebsch, M., Yokota, H., and
J. Korhonen, "Update Notifications for Proxy Mobile IPv6",
RFC 7077, November 2013.
8.2. Informative References
[3] IEEE, "802.11-2012 - IEEE Standard for Information
Technology - Telecommunications and information exchange
between systems Local and metropolitan area networks-
Specific requirements Part 11: Wireless LAN Medium Access
Control (MAC) and Physical Layer (PHY) Specifications.",
March 2012.
[4] Wi-Fi Alliance, "Wi-Fi Multimedia Technical Specification
(with WMM-Power Save and WMM-Admission Control) Version
1.2.0.", May 2012.
[5] IEEE, "Wireless LAN Medium Access Control (MAC) and
Physical Layer (PHY) Specification, Amendment 2: MAC
Enhancements for Robust Audio Video Streaming, IEEE
802.11aa-2012.", May 2012.
[6] 3GPP, "Guidelines for IPX Provider networks (Previously
Inter-Service Provider IP Backbone Guidelines) Version
11.0", GSMA Official Document IR.34 v11.0, November 2014.
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[7] 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Core Network and Services; Wireless
LAN control plane protocols for trusted WLAN access to
EPC; Stage 3 (Release 12)", 3GPP TS 23.244 12.1.0,
December 2014.
[8] 3GPP, "3rd Generation Partnership Project; Technical
Specification Group Services and System Aspects; Policy
and Charging Control Architecture (Release 13)", 3GPP TS
23.203 13.2.0, December 2014.
[9] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[10] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
June 2002.
Appendix A. LMA Initiated QoS Service Flow with IEEE 802.11aa
+-----------+
+----+ |+--+ +---+| +-------+
| MN | ||AP| |MAG|| | LMA |
+-+--+ ++-++--+-+-++ +---+---+
| | | |
+----------------------------------------------------------------+
| (0) establish connection session to mobile network |
+----------------------------------------------------------------+
| | | |
| | | | Policy
| | | |<----------
| | |UPN(QoS opt(2) | Update(1)
| ADDTS Reserve Request | |<-----------------|
| (TCLAS, TSPEC)(3) |<----| |
|<-------------------------| | |
| ADDTS Reserve Response | | |
| (TCLAS, TSPEC)(4) | | |
|------------------------->| | |
| |---->|UPA(QoS opt)(5) |
| | |----------------->|
| | | |
Figure 5: LMA initiated QoS service request with 802.11aa
In this use case shown in Figure 5, the LMA initiates the QoS service
request and IEEE 802.11aa is used to setup QoS reservation in the Wi-
Fi segment.
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(0) MN sets up best effort connectivity session. 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 PMIPv6 UPN (Update Notification) [2], as outlined in
Section 3.2.1, to the MAG with notification reason set to
QOS_SERVICE_REQUEST and acknowledgement requested flag set to
value of 1. The operational code in QoS option SHOULD be 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. 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
/MAG sends an ADDTS Reserve Request (IEEE 802.11aa) specifying
the QoS reserved for the traffic stream including TSPEC and TCLAS
element mapped from PMIPv6 QoS Traffic Selector to identify the
flow.
PMIPv6 parameters are mapped to TCLAS (Table 1) and TSPEC
(Table 4). If there are insufficient resources at the AP/WLC,
the MAG will not send and ADDTS message and will continue
processing of step (5).
Higher level StreamId in IEEE 802.11aa should be encoded as
discussed in Section 3.2.2.
(4) MN accepts the QoS reserved in the network and replies with ADDTS
Reserve Response.
(4) The MAG (AP/WLC) replies with UPA confirming the acceptance of
QoS options and operational code set to RESPONSE. The AP/WLC
polices flows based on the new QoS.
If there are insufficient resources at the AP in step (3), the
MAG sends a response with UPA status code set to
CANNOT_MEET_QOS_SERVICE_REQUEST (130).
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Authors' Addresses
John Kaippallimalil
Huawei
5340 Legacy Dr., Suite 175
Plano, TX 75024
USA
Email: john.kaippallimalil@huawei.com
Rajesh Pazhyannur
Cisco
170 West Tasman Drive
San Jose, CA 95134
USA
Email: rpazhyan@cisco.com
Parviz Yegani
Juniper
1194 North Mathilda Ave.
Sunnyvale, CA 94089-1206
USA
Email: pyegani@juniper.net
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