1. TGaq Transaction Protocol (update) Authors: Date: 2013-07-16 Michael Montemurro, BlackBerry

2. Abstract Transaction Protocol for TGaq Michael Montemurro, BlackBerry

3. Background • TGaq develops simple MAC protocol • Defines over-the-air messages only (PAM) • Meets low level requirements of use cases • Other Fora deal with higher layers (L2+) • Liaison to other fora of our use cases Michael Montemurro, BlackBerry

4. Transaction Protocol • Part of the PAM (Pre-Association Messages) • The TP is implemented as an advertisement protocol enabling it to be carried, over the IEEE 802.11 air interface, by the existing GAS mechanism. • Use a new advertisement protocol id “STP” – service transaction protocol (e.g. like RLQP) • New bit in AP extended capability IE Michael Montemurro, BlackBerry

5. Transaction Protocol • STP is different from ANQP • Not a request/response mechanism • Allows unsolicited push messages from the STA • Messages can carry information from non-AP STA to AP • ANQP is a network oriented protocol. STP is not for network discovery. Separate rules are needed. • STP can use broadcast. Michael Montemurro, BlackBerry

6. Michael Montemurro, BlackBerry

7. Michael Montemurro, BlackBerry

8. Transaction Protocol • A service discovery ULP within the mobile device wishes to send a message A to the LAN or external network (e.g. to discover a service). • Mobile device may need to discover BSS architecture • Send STP to AP, or to a proxy? • An STP Encapsulation message carries the ULP message A to the TXP. In turn the TXP passes the message to the co-located service discovery ULP. As the STP element type is STP Encapsulation the TXP recognises that no analysis is required. It merely forwards the message to the higher layer. Michael Montemurro, BlackBerry

9. Transaction Protocol • STP operates between the ULP entities within itself and that of the Service Transaction Proxy (TXP). • The ULP is not tunnelled, as this may require a proxy for multicast DNS. • More detail required. • Thoughts on possible Push mode: • Push mode could be troublesome during the discovery/scanning phase • Need some state on STA to do push mode (potentially after 802.11 Authentication or potentially during Association sequence) Michael Montemurro, BlackBerry

10. Michael Montemurro, BlackBerry

11. Transaction Protocol • ULP does not need to be standardised within Tgaq • deliberately hide the details of the ULP so that we can focus on MAC design • When the higher layer ULP responds with another message B, the TXP uses another STP Encapsulation message to transmit message B back to the mobile device including the STP token. If an error occurs in the TXP transaction a Return Code may be alternatively returned to the mobile. • When the STP Encapsulation message is received by the mobile terminal the contents are passed back to the service discovery ULP. Michael Montemurro, BlackBerry

12. Transaction Protocol • The message sequence is bi-directional and can be initiated by the ULP co-located with the TXP. Additionally STP does not need to “answer” Message A with a Message B, as it has no knowledge of how the ULP operates. • May require some IDs of ULP protocols and associate it with the encapsulation. • Possibly need to fragment large ULP frames. • Could just use GAS fragmentation • Possibly use a hash of a large ULP frame. (see 13-893r0) • Messages could be signed to provide some level of data integrity. • Need to do some additional work on defining the ULP ID space and its management Michael Montemurro, BlackBerry

13. Possible IE Michael Montemurro, BlackBerry

14. Data Integrity • Signature may be useful for data integrity, not security. Michael Montemurro, BlackBerry