1. Scalable Station Association Information Handling
January 2007
doc.: IEEE /1842r4
January 2007
Scalable Station Association Information Handling
Date:
Authors:
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Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

2. January 2007
Abstract
In this presentation, we investigate how to handle the legacy stations in the s Mesh WLAN and we propose three schemes to provide a better solution in managing the legacy station information among the MAPs.
Azman Osman Lim, et.al.

3. Legacy STA impacts 802.11s Mesh WLAN
January 2007
Legacy STA impacts s Mesh WLAN
Seamless integration and self-configuration
stations (legacy STAs) and s Mesh Access Points (MAPs).
Security issue
Man-In-The-Middle (MITM) Attack problem and etc.
Fully backwards compatibility
No change to existing legacy STAs is needed.
No interruption of a radio signal from legacy STA to MAP happens.
Shortage of 4-to-6 and 6-to-4 address conversion
4-address scheme for legacy STAs and 6-address scheme for MAPs.
Shortcomings of multi-radio configuration
Single interface for legacy STAs and multi-interface for MAPs.
Interoperability Problem
Path selection protocol for only MAPs and no routing table for legacy STA.
Azman Osman Lim, et.al.

4. 802.11s Path Selection Protocol
January 2007
802.11s Path Selection Protocol
Path selection protocol must be implemented on all MPs/MAPs to ensure baseline interoperability for
802.11s MPs/MAPs and s MPs/MAPs.
legacy STAs and legacy STAs.
legacy STAs and s MPs/MAPs.
In current s specification, two path selection protocols are defined.
Hybrid Wireless Mesh Protocol (HWMP) – default protocol.
Radio-aware OLSR (RA-OLSR) – optional protocol.
HWMP: So far, no Station Association Discovery Scheme to handle the legacy STAs.
RA-OLSR: LAB/GAB Scheme is applied to handle the legacy STAs.
Does this interoperability work???
We focus on RA-OLSR in this presentation.
Azman Osman Lim, et.al.

5. January 2007
Motivation
By using the RA-OLSR protocol, each MAP broadcasts LABA message periodically. This phenomenon gives a difficulty to handle a huge proxy table of each MAP.
Azman Osman Lim, et.al.

6. The problem of a huge proxy table for all MAPs
January 2007
The problem of a huge proxy table for all MAPs + +
MAP
Table +
STA
Table +
MAP
STA
Azman Osman Lim, et.al.

7. January 2007
Our Proposed Schemes
We propose three schemes to solve the problem of a huge proxy table in each MAP when the RA-OLSR protocol is applied.
Efficient LAB/GAB Management Scheme
Centralized Station Discovery Scheme
On-demand Station Discovery Scheme
Azman Osman Lim, et.al.

8. Efficient LAB/GAB Management Scheme
January 2007
Scheme 1:
Efficient LAB/GAB Management Scheme
Azman Osman Lim, et.al.

9. January 2007
Motivation
The periodical broadcasting of LABA/LABCA message will generate a large communication overhead throughout the network of s Mesh WLAN.
To solve the CID 3649, 3651, 5697, 5698, 5699, 5700 of comment resolution (07/0023r2)
Approach
We introduce a Local Association Update Checksum Advertisement (LAUCA) message to shrink down the overhead.
We introduce GABI_REQ and GABI messages to obtain the GAB in a shorter time with less overhead for a newly joined MP/MAP.
Azman Osman Lim, et.al.

10. Proposed LAUCA Message
January 2007
doc.: IEEE /1842r4
January 2007
Proposed LAUCA Message
“Local Association Base Checksum Advertisement (LABCA)” is changed to “Local Association Update Checksum Advertisement (LAUCA)”
LAUCA message consists of
an updated (associated/disassociated) STA address information; and
an updated checksum of the LAB.
Advantage: Overhead reduction of the LABA/LABCA method by using LAUCA method.
Disassociated STA Info
Proposed LAUCA Method
MAP
LAB
Associated STA Info
LAUCA
Disassociated STA Info
= Checksum
join
leave
leave
LABA
LABCA
MAP
MAP
join
LAB
Associated STA Info
MAP
Original LABA/LABCA Method
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

11. Proposed GABI_REQ and GABI Messages
January 2007
doc.: IEEE /1842r4
January 2007
Proposed GABI_REQ and GABI Messages
Define a GABI_REQ message to obtain a GAB Information (GABI) message from the nearest neighbor MP/MAP.
Upon receiving the GABI_REQ message, the nearest neighbor MP/MAP sends its own GABI message to the new MP/MAP.
Advantage: A new MP/MAP can obtain the GAB in a shorter time with less overhead.
new MP/MAP
Proposed Method
GABI_REQ
(unicast)
GAB
This MP/MAP is proactively obtaining the GAB.
GABI
Wireless Mesh Networks
Wireless Mesh Networks
LABA
LABA
LABA
ABBR
(Unicast)
new MP/MAP
GAB
Current Method in the s draft
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

12. Centralized Station Discovery Scheme
January 2007
Scheme 2:
Centralized Station Discovery Scheme
Azman Osman Lim, et.al.

13. January 2007
Motivation
The periodical sharing of GAB information by all the MPs/MAPs will generate a large communication overhead in the network of s Mesh WLAN.
To solve the CID 5701, 5702, 5703 of comment resolution (07/0023r2)
Approach
By assuming the periodical collecting GAB information is configured and the 6-address scheme is applied, we propose a Centralized Station Discovery Scheme, which allows the Root to collect the LABA messages from all MAPs and provide the required entry of the proxy table to MPs/MAPs.
Azman Osman Lim, et.al.

14. Unicasting the LABA message to the Root
January 2007
doc.: IEEE /1842r4
January 2007
Unicasting the LABA message to the Root
Periodically, e.g., MAP-16 generates a LABA message and sends it to the Root.
Root constructs the GAB based on the LABA messages from all MAPs.
Root X 1 3 2 5 9 4 7 6 8 12 11
LABA
message 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

15. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
When a source station S1 wants to communicate with a destination station S2, S1 sends its data message to MAP-15.
Upon receiving the data message from S1, MAP-15 transforms the header of the data message to the header that is containing 6-address format and directs it to the Root.
Root X 1 3 2 5 9 4
Data message 7 6 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

16. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
Upon receiving the data messages from MAP-15, the Root that is knowing the MAP-16 is associating S2 redirects the data message to the MAP-16.
Upon receiving the data message from the Root, the MAP-16 sends the data message to S2.
Root X 1 3 2 5 9 4 7 6
Data message 8 12 11 10 15 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

17. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
To perform a centralized station discovery scheme, the Root informs the MAP-15 of address set, which contain the address of S2 that is corresponding to the address of MAP-16.
Upon receiving the address set message from the Root, the MAP-15 sends the S1’s data message to MAP-16 along the route, which is maintained by the OLSR’s normal functions.
Root X 1 3 2
address set of S2 and MAP-16 5 9 4 7 6 8 12 11 10 15
Data message 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

18. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
The route within the MAPs that is maintained by the OLSR’s normal functions will not expire.
In contrast to that, an entry of the route to station inevitably expired unless it is updated periodically.
Root X 1 3 2 5 9 4 7 6 8 12 11 10 15
Data message 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

19. On-demand Station Discovery Scheme
January 2007
Scheme 3:
On-demand Station Discovery Scheme
Azman Osman Lim, et.al.

20. January 2007
Motivation
The periodical sharing of GAB information by all the MPs/MAPs will generate a large communication overhead in the network of s Mesh WLAN.
To solve the CID 4605, 4606, 4607, 5701, 5702, 5703 of comment resolution (07/0023r2)
Approach
By assuming the periodical sharing GAB information is not configured, we propose an On-demand Station Discovery Scheme, which allows a MP/MAP to broadcast an Association Base Address Request (ABAR) message to discover a station and also allows a MAP to unicast a LABA message to inform the discovered station information.
Upon receiving the LABA message, the MP/MAP treats the LABA message as an entry of discovered station in its proxy table.
This proxy table indirectly takes the role of GAB.
Azman Osman Lim, et.al.

21. On-Demand Station Discovery Scheme
January 2007
On-Demand Station Discovery Scheme
When the MP/MAP searches for the MAP that is associating the destination STA, the MP/MAP generates an Association Base Address Request (ABAR) message and broadcasts it to the whole network.
Upon receiving the ABAR message, the MAP that is associating the destination STA replies a LABA message in unicasting manner to the MP/MAP originator.
Octets: 6 … 6
STA address
Fields specific to RA-OLSR ABAR element
Field
Value/Description
STA address
A list of source STA address that is requested by a MAP that is associating the destination STA.
Azman Osman Lim, et.al.

22. When S1 wants to communicate to S2
January 2007
When S1 wants to communicate to S2
When a source station S1 wants to send a data to a destination station S2, first S1 sends it to MAP-15.
When the MAP-15 has no entry in its own proxy table, MAP-15 broadcasts an ABAR message to request for the address of S2. 1 3
Flooding ABAR message 2 5 9 4 7 6 8 12 11 10 15 14 13 16 S2 17 18 S1 21 19 23 22 20
Azman Osman Lim, et.al.

23. When S1 wants to communicate to S2
January 2007
When S1 wants to communicate to S2
Upon receiving the ABAR message, the MAP-16 unicasts a LABA message, which contains a “address set.”
In this address set, it contains the address of S2 that is corresponding to the address of the MAP originator. 1 3 2 5 9 4 7 6 8 12 11 10 15 14
LABA message 13 16 S2 17 18 S1 21 19 23 22 20
Azman Osman Lim, et.al.

24. When S1 wants to communicate to S2
January 2007
When S1 wants to communicate to S2
Upon receiving the LABA message, the MAPs along the route (e.g., MAP-13, MAP-14, MAP-17) and also MAP-15 insert the LABA message as an entry of S2 in its proxy table.
This proxy table indirectly takes the role of GAB.
At last, the MAP-15 sends the S1’s data to S2 via the route between MAP-15 and MAP-16. 1 3 2 5 9 4 7 6 8 12 11 10 15 14 13 16
Data message 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.

25. January 2007
Conclusions
We addressed the problem of a huge proxy table in each MAP when the RA-OLSR is applied.
We also proposed three schemes to solve the problem of huge proxy table in each MAP:
Efficient LAB/GAB Management Scheme
Centralized Station Discovery Scheme
On-demand Station Discovery Scheme
Azman Osman Lim, et.al.

26. January 2007
Straw Poll
Shall we consider the first scheme (Efficient LAB/GAB Management Scheme) and prepare texts based on it for adoption ?
Yes: No: Abstain:
Shall we consider the second scheme (Centralized Station Discovery Scheme) and prepare texts based on it for approval ?
Shall we consider the third scheme (On-demand Station Discovery Scheme) and prepare texts based on it for approval ?
Azman Osman Lim, et.al.

27. References IEEE P802.11s Draft D1.0
January 2007
References
IEEE P802.11s Draft D1.0
Comments Resolution of IEEE P802.11s, 11-07/0023r02
Azman Osman Lim, et.al.

28. January 2007
Backup Slides
Azman Osman Lim, et.al.

29. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
If the entry of the route to S2 is expired, the MAP-15 directs the data message to Root.
Root X 1 3 2 5 9 4
Data message 7 6 8 12 11 10 15
Expired route 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

30. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
When the MAP-15 sends the LABA message (with a list of active destination stations) to the Root.
Root X 1 3
destination STA (e.g., S2)s’ list
LABA message with active 2 5 9 4 7 6 8 12 11 10 15
Data message 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.

31. When S1 wants to communicate with S2
January 2007
doc.: IEEE /1842r4
January 2007
When S1 wants to communicate with S2
Upon receiving the LABA message with active destination STAs’ list from the MAP-15, the Root sends a message of the address sets’ list that is corresponding to the active destination STAs’ list to the MAP-15.
In each address set, it contains the address of active destination station that is corresponding to the address of the MAP and the Destination Sequence Number (DSN) of active destination station. With such information, the route to the active destination station is being updated.
Root X 1 3 2 5
a list of address sets 9 4 7 6 8 12 11 10 15
Data message 14 13 16 17 18 S1 21 S2 19 23 22 20
Azman Osman Lim, et.al.
Azman Osman Lim, et.al.