1. Proposed DLS Teardown Date: 2006-03-07 Ovadia, Ginzburg, Intel
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Ovadia, Ginzburg, Intel

2. Abstract
This submission addresses DLS teardown conditions that are not included in IEEE ma/D5.1 draft Standard.
Ovadia, Ginzburg, Intel

3. Agenda DLS Teardown Process DLS Teardown Problem Proposed solution
AP-initiated DLS teardown
Ovadia, Ginzburg, Intel

4. DLS Teardown Assumptions:
Initiating & recipient QSTAs are in the same BSS and still within reach of the QAP.
Initiating & recipient QSTAs are able to reliably transmit and receive frames over
the WM before starting the DLS teardown operation.
Ovadia, Ginzburg, Intel

5. DLS Teardown Problem
Under certain operating conditions, one or both of the STAs participating
in the DLS link suddenly can not ‘hear’ the AP, but can still hear its
DLS peer.
What is the status of the DLS link?
Who is responsible for DLS link teardown?
Wireless
AP / Router
DLS Request
DLS Response
DMA TV
Bidirectional DLS PC PC
Ovadia, Ginzburg, Intel

6. Proposed Solution
DLS teardown frame is sent directly to the peer STA (1) by either
the DLS initiating STA or by the STA that can not ‘hear’ the AP
The peer STA sends the DLS teardown frame to AP (2)
L2 ACK is sent to Peer STA (DMA)
AP removes the link from its DLS list
Wireless
AP / Router
DLS Request
DLS Response
(2)
Bidirectional DLS
DMA TV
DLS Teardown frame (1)
Ovadia, Ginzburg, Intel

7. Proposed Solution (continue)
Conditions for direct DLS Teardown include:
One or both of the STAs move out-of-range of the AP (peer
STAs can still ‘hear’ each other)
Sudden reboot of the STA (assuming DLS inactivity timer expired)
If target STA wants to go off channel (e.g., channel scanning)
Order
Information 1
Category (2) 2
Action (2) 3
Destination MAC Address 4
Source MAC Address 5
Reason Code (46)
Add new Reason Code to describe
a new condition
Ovadia, Ginzburg, Intel

8. DLS Teardown Reason Code Table
Reason Code Field
Applicable at
QSTA_LEAVING 36
Non-AP QSTA
END_DLS 37
UNKNOWN_DLS 38
TIMEOUT 39
STAKEY_MISMATCH 45
PEER_INITIATED 46
AP and Non-AP QSTA
AP_INITIATED 47
Proposed
Reason
Codes
* The Peer STA sends DLS Teardown frame to AP.
Ovadia, Ginzburg, Intel

9. AP-initiated DLS Teardown
Under certain operating conditions, an AP can remove one or more STAs from its BSS list. The DLS teardown should be applied to specific DLS session.
These conditions include:
If STA left the BSS
Teardown with Reason Code = 36
Sudden reboot or failure of the STA
AP detects that the STA left its BSS
AP loses its DLS session state
 Teardown with Reason Code =47
If these STAs have open DLS connections, then the AP send a DLS Teardown message to all the peers of the removed STAs.
Ovadia, Ginzburg, Intel

10. Feedback?
Ovadia, Ginzburg, Intel