Transcript 11-13-0788-00-00aq-transaction-protocol.ppt

July 2013
doc.: IEEE 802.11-13/0788r0
TGaq Transaction Protocol
Date: 2013-07-16
Authors:
Name
Company
Michael Montemurro
BlackBerry
Stephen McCann
BlackBerry
Submission
Address
4701 Tahoe Blvd
Mississauga, ON, Canada
L4W0B4
200 Bath Road, Slough,
Berkshire, SL1 3XE, UK
Slide 1
Phone
email
+1-905-629-4746
x14999
mmontemurro@blackberry.com
+44 1753 667099
smccann@blackberry.com
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
Abstract
Strawman Transaction Protocol for TGaq
Submission
Slide 2
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
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
Submission
Slide 3
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
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)
• 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
Submission
Slide 4
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
Network
Service Query Messages
AP2
Local Access
Network
Service
Transaction Proxy
(TPX)
AP1
Pre-association Messages
STA
Submission
Slide 5
Michael Montemurro, BlackBerry
July 2013
STA
doc.: IEEE 802.11-13/0788r0
Service
Transaction
Proxy
AP
1) Initialisation
2) Request (token, “3D Printer”)
3) Response (token, “available”, destination_address)
Submission
Slide 6
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
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).
• 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.
Submission
Slide 7
Michael Montemurro, BlackBerry
July 2013
Upper Layer
Protocol
(ULP)
doc.: IEEE 802.11-13/0788r0
STA
AP
TXP / ULP
1) ULP message A
2) Encapsulation (token, “ULP message A”)
3) Encapsulation (token, “ULP message B”)
4) ULP message B
Submission
Slide 8
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
Transaction Protocol
• 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.
Submission
Slide 9
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
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.
• Messages could be signed to provide some level of data
integrity.
Submission
Slide 10
Michael Montemurro, BlackBerry
July 2013
doc.: IEEE 802.11-13/0788r0
Possible IE
Octets:
Submission
ID
STP
Token
Length
ULP ID
ULP payload
2
2
2
1
variable
Slide 11
Signature Length
(optional)
Signature
(optional)
2
variable
Michael Montemurro, BlackBerry