1. Management Frame Policy Definition
Month Year
Month Year
doc.: IEEE yy/xxxxr0
doc.: IEEE yy/xxxxr0
Management Frame Policy Definition
Date:
Authors:
Slide 1
Santosh Pandey, Cisco Systems
Page 1
John Doe, Some Company
John Doe, Some Company

2. Outline Requirements addressed
High level exchange – Association enterprise exchange
Policy advertisement
Policy request/report
Policy change request/response
Pre-association/Roaming policy
Legacy STA
IBSS – Exchange
Unless specified otherwise, all references to AP and STA in this presentation imply ae capable AP and ae capable STA respectively

3. Requirements to be addressed
Management policy definition and advertisement
Allow application of policy to groups of management frames
Advertise management frames’ priorities in beacons concisely
Pre-association policy advertisement and implementation
Post-association policy advertisement and implementation
STAs can exchange policies on demand
STAs can request change in policy
Details
ae-proposal-for-prioritization-of-management-frames.doc
ae-tech-proposals.doc
ae-tgae-requirements-and-use-cases.doc

4. High level exchange – Association enterprise exchange
Default policy is to send all management frames at highest priority (AC_VO)
Pre-association
Extended Capabilities IE bit will be set to indicate STA is ae capable. This IE is included in Beacons, Association Request/Response, Reassociation Request/Response and Probe Request/Response
The pre-association policy advertisement and adoption is described later
Association
AP shall include the entire management frame policy in (Re)Association Response
STA shall adopt this policy post-association to send all management frames
Post-Association policy
STA shall request associated AP for changing priority of any management frame if needed
AP shall respond will accept/reject response. The reject response shall include a reason code to indicate if the STA may or may not retry later
Any management frames whose priority is not modified by Management Frame Policy is sent at AC_VO.
Sending entire policy in the beacon may get excessive
11 subtype frames (association etc)
2 Action/Action no ack which have category/action values
22 Categories defined (including 11s – <ANA>)
24 Action values (max) in WNM (categorty 10)
Out of 140 management frames, 79 management frames were identified to be sent at low or medium priority (Only high, low, medium considered in ae-management-frame-analysis.xls)

5. Management Frame Policy IE
Element ID
Length
Priority Definition Count
Priority definition field #1
Priority definition field #2 (optional) …
Priority Definition field #n (optional)
Octets: 1
variable
This IE will be used to advertise and exchange management frame policy between STAs
This IE is sent in Beacons, (Re)Association Request/Response and Probe Request/Response
Contents of IE in beacon frame should only be for frames which can only be transmitted in state 1 and 2. Pre-association details in later slides.
It will also be used in a new policy report frame and policy change request/response frame describe later
Priority Definition Count field indicates the number of priorities defined in the IE
List of Priority Definition fields contains one or more Priority Definition fields

6. Priority Definition Field (PrDf)
Design guiding principles:
To indicate priority of all management frames efficiently
Allow grouping of management frames having the same priority
Future proof – no change needed when future amendments add new management frames

7. Priority Definition Field: Type_PrDf=0
Bits: B0 B1 B2 B3 B4 B7 B0 B3 B4 B7 B0 Bn
Priority Definitio n Field Type
0 0 U M
Priority Definition Field Length
TID
Mgmt Frame Subtype
Category Value (optional)
Action Value Bitmap (optional)
Octets: 1
variable
Priority Definition Field Type (Type_PrDf) subfield is 2 bits in length and defines the structure of the Priority Definition field.
Unicast bit (U) is set if the management frames priorities defined in PrDf is applicable to unicast management frames
Multicast bit (M) is set if the management frames priorities defined in PrDf is applicable to multicast management frames
Priority Definition Field Length (Length_PrDf) subfield is 4 bits in length and defines the length in octets of the Priority Definition field, excluding the 1 octet used for Type_PrDf and Length_PrDf subfields. This can support maximum of 15 octets.
TID subfield is 4 bits in length and is defined in The management frames indicated in this priority definition field are sent at priority defined by this TID.
Management Frame Subtype (Subtype_PrDf) subfield is 4 bits in length. The values are defined in Table 7-1 for management frame type. For example,
a value of 0000 indicates Association Request management frame
a value of 1101 indicates Action management frame
Category Value (CV_PrDf) subfield is 1 octet in length and is included only for frames of subtype Action and Action No Ack
For example, a Category Value of 10 will indicate WNM category action frame when Subtype_PrDf = Action subtype
Action Value Bitmap (AVB_PrDf) subfield length is variable and it indicates the corresponding Action values
For example, setting Bit 0 and Bit 1 will indicate Event Request/Response when Subtype_PrDf = Action subtype and CV_PrDf = WNM Category
In all for any given category, a maximum of 104 action value frames can be supported in this format
This subfield is zero padded to complete any incomplete octet

8. Priority Definition Field: Type_PrDf=0
Action Value Bitmap subfield may be included for frames of subtype Action and Action No Ack and when the Category subfield is included
Each bit in the Action Value Bitmap subfield is mapped to the corresponding action value.
Multiple Action frames are indicated by setting multiple bits
Length_PrDf (octet(s))
Subtype_PrDf
CV_PrDf
AVB_PrDf
Description 1  
Policy to be applied to all management frames of the corresponding subtype 2
Policy to be applied to all action frames of corresponding category value belonging to the management subtype frames
Var
Policy to be applied to only Action frames indicated via the action value bitmap for corresponding category value and management subtype frames
Table: Valid combination of optional fields to be included in Priority Definition Field

9. Example 1 For example, above frame
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 3 13
Octets:
Action Value Bitmap B0 B1 B2 B3 B4 B5 B6 B7
Priority Definition Field
For example, above frame
TID = 1 (AC_BK)
Subtype = 13 (Action)
Category Value = 0 (Spectrum management)
Action Value Bitmap subfield (B7-B0) = , indicates frames with Action value = 0 and 1 (i.e. Measurement Request/Response respectively)
This indicates that the Measurement Request/Response of Spectrum Measurement Category will be sent at AC_BK priority

10. Example 2 For example, above frame
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 2 13 11
Octets:
Priority Definition Field
For example, above frame
TID = 0 (AC_BE)
Subtype = 13 (Action)
Category Value = 11 (unprotected WNM)
This indicates that all unprotected WNM Action frames will be sent at AC_BE priority

11. Example 3: Mgmt Frame Policy IE with 3 priority definitions
Element ID
<ANA>
Length 8
Priority Definition Count 2
Octets: 1
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 3 13
Octets:
Action Value Bitmap
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 2 13 11
Octets:
The above defines complete management policy IE which includes different priorities defined in examples 1-2 in previous slides

12. Considering trade offs for priority definition
Brute force – specifying subtype, category, action value for each management frame priority
Pros
Future proof – no change needed for any future amendments
Cons
Requires minimum 3 bytes for each management frame (TID, Subtype, Category, Action)
No grouping possible, each frame has to be individually specified
Very large size (237 octets) considering that 79 of the 140 management frames priority may need to be changed to low priority (from ae-management-frame-analysis.xls)
Lookup Table – have a table of bitmap for all the management frames
Can specify all the management frame for a given priority in a single Priority Definition field
Selectively define management frames in the table (implicitly club request/response to a single priority)
Size can be limited (with current management frames) to 19 octets
Requires table which needs to be updated for every amendment which introduces management frames
Table may grow too large for future
Extra lookup overheads in STA
Proposed scheme
Provides some level of grouping/aggregation. Logically, priorities would be changed for contiguous set of Action values
All frame subtypes or categories can be aggregated
Requires minimum 2 octets and maximum 7 octets for all current subtype-category pairs. 52 octets will be required to change priorities of 79 of the 140 management frames (from ae-management-frame-analysis.xls)
A Priority Definition field can support only a single subtype-category pair of management frames. Multiple Priority Definition field is required for unique subtype-category pairs to be defined
Brute force 237 octets
79 x 3 = 237
Table lookup
140 management type = 1 octet TID + 18 octets map = 19 octets
Proposed scheme
52 octets for our size - Used only Field Type field = 00,
Default high – 1 octet
1 M subtype (ATIM) – 2 octets
Some Low (1 octet Action Value bitmap) Categories = 0, 1, 5, 7, mesh – 4x5 = 20 octets
Some Low (2 octet Action Value bitmap) Categories = 4, Protected dual – 5x2 = 10 octets
Some Low (4 octet Action Value bitmap) Categories = x1 = 7 octets
All Low (0 octet Action Value bitmap) Categories = 2, 12, 126, x4 = 12 octets

13. Optimizations: Policy Definition IE
Contents of IE in beacon frame should only be for frames which can only be transmitted in state 1 or 2.
The complete policy shall be sent to STA in (Re)Association Response
If same management frame is indicated in multiple Priority Definition fields, the management frame is sent at the priority defined in the last Priority Definition field
This can be used to set the priority of the entire category and change only specific action frames
For example, to set the entire WNM category (10) at AC_BE priority with the exception of Event Request/Report (Action value = 0,1), which are to be sent at AC_BK, the following sequence of Priority Definition fields can be used in the Management Frame Policy IE
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 2 13 10
Octets:
Type_PrDf U M
Length_ PrDf
TID
Subtype_ PrDf
Category Value 1 3 13 10
Octets:
Action Value Bitmap

14. Management Policy Exchange action
Table 7-24—Category values
Code
Meaning
See Subclause
Robust
<ANA>
Management Policy Exchange (MPE) ?
Table X -- MPE Action field values
Action field value
Description
Policy Query 1
Policy Response 2
Policy Config Request 3
Policy Config Response 4
Policy Config Delete
The management policy can be exchanged and changed using the above action frames

15. Policy Query
Category
Action
Dialog Token
Octets: 1
Policy Request frame body format
This frame is used to request policy from an STA to another
The Category field is set to the value indicating the MPE category, as specified in Table 7-24 in
The Action field is set to the value indicating Policy Request, as specified in Table X
The Dialog Token field is set to a nonzero value chosen by the STA sending the policy request to identify the request/report transaction.

16. Policy Response
Category
Action
Dialog Token
Management Frame Policy element
Octets: 1
variable
Policy Report frame body format
This frame is used to indicate the policy when a policy request is received from an STA
The Category field is set to the value indicating the MPE category, as specified in Table 7-24 in
The Action field is set to the value indicating Policy Report, as specified in Table X
The Dialog Token field is set to the nonzero value of the corresponding Policy Request frame.
If the Policy Report frame is being transmitted other than in response to an Policy Request frame, then the Dialog token is set to zero –not required, any reason why this will be needed?

17. Policy Config Request
Category
Action
Dialog Token
Management Frame Policy element
Octets: 1
variable
Policy Change Request frame body format
This frame is used to request change in management frame policy configuration
The Category field is set to the value indicating the MPE category, as specified in Table 7-24 in
The Action field is set to the value indicating Policy Change Request, as specified in Table X
The Dialog Token field is set to a nonzero value chosen by the STA sending the policy request to identify the request/response transaction.
The Management Frame Policy element is as define earlier.
When sent by an associated STA, this frame will indicate the new management frame policy requested by the STA
Management frames not indicated in this request are sent at policy advertised by associated AP
Only unicast allowed
When sent by an AP, this frame will indicate the new management frame policy that STAs associated to this AP shall adopt
Only unicast allowed. Multicast is discussed later
This will be used to set policy by AP post-association to some or all associated STA

18. Policy Config Response
Month Year
doc.: IEEE yy/xxxxr0
Policy Config Response
Category
Action
Dialog Token
Status Code
Octets: 1
Policy Change Response frame body format
This frame is used to respond to a policy config change request
The Category field is set to the value indicating the MPE category, as specified in Table 7-24 in
The Action field is set to the value indicating Policy Change Response, as specified in Table X
The Dialog Token field is set to the nonzero value of the corresponding Policy Change Request frame.
The Status Code field contains status code in response to Policy Change Request frame as defined in adjacent Table.
Only unicast frames allowed
Status Code Definitions
Status Code
Status code description
Accept 1
Reject – don’t retry 2
Reject – may retry
May add partial accept later
John Doe, Some Company

19. High level management policy exchange
Policy Config Request
Requestor
Responder
Action
Policy Config Response
Unicast AP
STA
STA adopts policy
Sends response
AP may or may not allow STA to change policy
Non-AP STA
STA may or may not adopt policy
(Re)Association Request/Response will be used to exchange complete management policy during association
Policy Query/Response can only be unicast
Multicast may lead to response storm in network
Policy Config Request/Response actions are governed by the adjacent table
Policy Config Request/Response combinations

20. Policy Config Delete
Category
Action
Dialog Token
Octets: 1
Policy Change Request frame body format
This frame is used to delete the change previously requested in management frame policy configuration using Policy Config Request
The Category field is set to the value indicating the MPE category, as specified in Table 7-24 in
The Action field is set to the value indicating Policy Config Delete, as specified in Table X
The Dialog Token field is set to the dialog token value used in the Policy Config Request
This will be used to set policy by AP post-association to some or all associated STA

21. Other cases and open issues
Pre-association
In AP beacons, only the policy for pre-association management frames to be sent at non-default priority will be included
All unicast management frames to the AP (by unassociated STAs) shall be sent at the policy advertised in AP beacon
Multicast management frames? Frames to other APs? Default priority?
AP may configure priority of STA post-association
Policy Config Request frames will be used
Multicast may induce unreliability – no certainty that the STA received the policy definition or not, which may lead to sequence number issues. So should we only allow unicast configuration? Is there a group address response – can 11aa help?
Roaming
Associated STA shall follow the associated AP management policy to send management frames (e.g. Probe Request) to other APs in the same ESS
If the target AP is in different ESS?
If associated AP is a legacy AP, then should the STA adopt the policy of the target AP if it received the management frame policy in the target AP beacon ?
Legacy STA
An 11ae capable STA shall associate in 11ae mode to an 11ae capable AP.
An 11ae capable STA shall associate in legacy mode to a non 11ae capable AP.
A non-11ae capable STA shall associate in legacy mode to an 11ae capable AP.
An 11ae capable STA shall adhere to the policy advertised by the 11ae capable AP.
Any management frame not defined in the policy defaults to the AC_VO
Policy exchange in IBSS shall be carried out using Management Policy Exchange Action frames
As default action drop the packet when received at incorrect priority?
Sending entire policy in the beacon may get excessive
11 subtype frames (association etc)
2 Action/Action no ack which have category/action values
22 Categories defined (including 11s – <ANA>)
24 Action values (max) in WNM (categorty 10)
Out of 140 management frames, 79 management frames were identified to be sent at low or medium priority (Only high, low, medium considered in ae-management-frame-analysis.xls)