doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 1 Simplified DLS Action Frame Transmission in 11Z Date: Authors:

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 2 Simplified direct link setup frame transmission Solution to frame reordering Backup Slides

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 3 Tunneled Direct Link Setup (TDLS) in [1] TDLS action frames are encapsulated in data frames as data frame payload. Encapsulated TDLS action frames go through an AP path from STA1 to STA2 –An AP transparently forwards encapsulated TDLS management action frames. –An AP is unaware of TDLS management frames that it forwards! AP Path STA1 AP STA2 1a 2a Direct Link 1b 2b MAC Data Header LLC/SNAP Remote Frame Type TDLS Packet Type TDLS Information FCS Data Frame Payload Octets:24/ Variable4

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 4 Problems with TDLS MAC layer entity in a STA has to analyze the ethertype octet at the link layer in each data frame that it accepts. –It violates IEEE 802 architecture. –It puts much overhead on the MAC layer entity. Some overhead is put in AP. –An AP has to forward TDLS action frames. AP Path STA1 AP STA2 1a 2a Direct Link 1b 2b

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 5 Simplified Direct Link Setup Frame Transmission New DLS action frames are defined with new action type. New DLS action frames are sent between two STAs directly –New DLS action frames are not encapsulated in MAC data frames. –An AP does not forward the proposed DLS action frames. AP Path STA1 AP STA2 Direct Link Path 1 2 New DLS action frame path. Management Frame Header Category Action Value TDLS Information FCS Management Frame Payload Octets: Variable 4

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 6 PROs of Simplified DLS Frame Transmission PROs –This method does not violate the 802 architecture. –This method does not need a new ethertype octet. –The MAC entity does not need to analyze ethertype in each data frame! –An AP does not forward the proposed DLS action frames. AP Path STA1 AP STA2 Direct Link Path 1 2 SDLS action frame path.

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 7 Simplified direct link setup frame transmission Solution to frame reordering Backup Slides

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 8 Solution to Frame Reorder When STA1 sends a Tx Path Switch Request with the direct path indication, it shall stop transmitting frames to STA2 through the AP. STA1 shall buffer the frames to STA2. When STA1 receives a Tx Path Switch Response with the direct path indication, it starts a delay timer. When the delay timer times out, STA1 starts to transmit frames to STA2 through direct link path. AP Path STA1 AP STA2 Direct Link Path

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 9 Reference [1] 11-07/2515r8, Tunneled Direct Link Setup (TDLS), Menzo Wentink etc.

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 10 Simplified direct link setup frame transmission Solution to frame reordering Backup Slides

doc.: IEEE /2952r2 Submission Dec 2007 L.Chu Etc.Slide 11 [Comment] A station normally receives only frames from the AP, but in your case it also needs to receive frames from any other TA. This does not seem right. It appears like you assume that a direct link is already in place before setting one up? [Answer] This is a very good point. Actually I asked this question to myself many times when I prepared this presentation. You are right, a station normally receives only frames from the AP in a infrastructure BSS. My assumption is that if a station implements 11z DLS, it will receive only new DLS management frames from another non-AP station directly before DLS connection is set up. No data frames are allowed being transmitted between two non-AP stations before the DLS is set up. So this does not means that a direct link is already in place before setting one up. This is what will be defined in 11z standard. This is similar to the security association between two stations. Unprotected data frames are not allowed between two stations before security association is set up. But security management frames are allowed before this security association is set up. [Comment] How do you know whether the intended peer station is in power save or not? [Answer] The initiator does not need to know if the intended peer is in power save or not. If the intended peer station is in power save state, the initiator can not set up a direct link any way. So in this case, the initiator will fail to set up a direct link with the destination after being timing out. It can try again later if it wants. [Comment] How do you propose to setup a secure direct link without the secure connection via the AP? [Answer] To my understanding, it is the master session key that authenticates the peer station. If peer stations have master session key of another station, they can authenticate each other and set up DLS security association. The master session key may be got through the pre-installed key or the security connection with AP to the AAA server. Comments And Replies