1. Siemens Partial Proposal for WLAN Mesh Networking
June 2005
doc.: IEEE /0593r0
June 2005
Siemens Partial Proposal for WLAN Mesh Networking
Date:
Authors:
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Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

2. June 2005
doc.: IEEE /0593r0
June 2005
Abstract
This presentation is about the “Siemens Partial Proposal for WLAN Mesh Networking” (doc 11-05/0592r0) in response to the Call for Proposals of the IEEE s task group. We consider a mainly unmanaged WLAN mesh network. All mesh points have to authenticate in order to become part of the WLAN mesh network. Mesh points can be both access point devices and client devices. Our proposed WLAN mesh networks with wireless multi-hop communication can be deployed in different usage scenarios: residential and home networks, office networks, campus, community, and public access networks, as well as public safety networks.
The proposal is centered around but is not exclusively about multi-hop path selection. A layer 2 adaptation of the AODV routing protocol is proposed. An important aspect is extensibility. Furthermore we provide contributions to security in WLAN mesh networks and to interworking.
Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

3. Overview of Presentation
June 2005
Overview of Presentation
Scope of proposal
Applicable usage scenarios
Mesh path selection
route discovery
routing management messages
routing metrics
proactive routing towards mesh portal
Mesh data frame
Broadcast
Beaconing
Mesh Portal and Interworking
Security
Extensibility
Summary
References
Michael Bahr, Siemens AG, Corporate Technology

4. Scope of Proposal Main Focus Contributions General information
June 2005
Scope of Proposal
Main Focus
wireless multi-hop routing
extensibility
Contributions
Interworking / Mesh Portal
Security
General information
Consider mainly unmanaged WLAN mesh network
Mesh points can be both access points and client devices.
Mesh points in a WLAN mesh network are peers.
All mesh points have to authenticate in order to become part of the WLAN mesh.
WLAN mesh is located in WDS.
Deployable in several usage scenarios
Michael Bahr, Siemens AG, Corporate Technology

5. Applicable Usage Scenarios
June 2005
Applicable Usage Scenarios
Residential Office
Campus / Community / Public Access Public Safety
Michael Bahr, Siemens AG, Corporate Technology

6. June 2005
Mesh Path Selection
reactive routing protocol for path selection in WLAN mesh networks with multiple wireless hops
adaptation of Ad hoc On-demand Distance Vector routing protocol (AODV) [2]
sequence numbers for chronological order of routing information
layer 2 routing protocol  uses MAC addresses
additional routing metrics besides hop count
routing control messages as information elements in action management frame
route request, route reply, route reply acknowledgement, route error
proactive routing towards mesh portal
flexible use of routing metrics
Michael Bahr, Siemens AG, Corporate Technology

7. Route Discovery n p l k o m S a q D j c g i f e b h June 2005 RREQ
Originator o m S a
Destination q D j c g i f e b h
RREQ
RREP
reverse route
route
Michael Bahr, Siemens AG, Corporate Technology

8. Route Discovery n p l k o m S a q D j c g i f e b h June 2005 RREQ
Originator o m S a
Destination q D j c g i f e b h
RREQ
RREP
reverse route
route
Michael Bahr, Siemens AG, Corporate Technology

9. Route Discovery n p l k o m S a q D j c g i f e b h June 2005 RREQ
Originator o m S a
Destination q D j c g i f e b h
RREQ
RREP
reverse route
route
Michael Bahr, Siemens AG, Corporate Technology

10. Route Discovery n p l k o m S a q D j c g i f e b h June 2005 RREQ
Originator o m S a
Destination q D j c g i f e b h
RREQ
RREP
reverse route
route
Michael Bahr, Siemens AG, Corporate Technology

11. Route Discovery n p l k o m S a q D j c g i f e b h June 2005 RREQ
Originator o m S a
Destination q D j c g i f e b h
RREQ
RREP
reverse route
route
Michael Bahr, Siemens AG, Corporate Technology

12. Route Request Information Element (RREQ)
June 2005
Route Request Information Element (RREQ)
flags
gratuitous route reply
destination only
unknown destination sequence numbers
mesh portal
Michael Bahr, Siemens AG, Corporate Technology

13. Route Reply Information Element (RREP)
June 2005
Route Reply Information Element (RREP)
flags
acknowledgement
destination is mesh portal
route reply acknowledgement information element (RREP-ACK)
Michael Bahr, Siemens AG, Corporate Technology

14. Route Error Information Element (RERR)
June 2005
Route Error Information Element (RERR)
flags
no delete
Michael Bahr, Siemens AG, Corporate Technology

15. Routing Metrics hop count 0 .. n optional routing metrics
June 2005
Routing Metrics
hop count
simple and basic routing metric
backup routing metric
0 .. n optional routing metrics
Michael Bahr, Siemens AG, Corporate Technology

16. Proactive Routing towards Mesh Portal
June 2005
Proactive Routing towards Mesh Portal
assumption: subtantial fraction of traffic transits mesh portal
usage is optional
mesh portal initiated:
mesh portal periodically annouces its existence  RREP IE in beacon
mesh points put received RREP with updated metrics into their own beacon
mesh point uses path with best path metric
mesh point initiated:
mesh points do route discovery for mesh portals (mesh portal flag set, destination is broadcast address)
only mesh portal answers with RREP
Michael Bahr, Siemens AG, Corporate Technology

17. Mesh Data Frame new subtype 1101 for data frames: Mesh Data
June 2005
Mesh Data Frame
new subtype 1101 for data frames: Mesh Data
mesh data frame format:
Michael Bahr, Siemens AG, Corporate Technology

18. Extensions of Mesh Data Frame
June 2005
Extensions of Mesh Data Frame
time-to-live (TTL) field
flags
mesh data frame options
variable number of options
Michael Bahr, Siemens AG, Corporate Technology

19. Mesh Data Frame Option June 2005
Michael Bahr, Siemens AG, Corporate Technology

20. Broadcast link-local mesh-wide same as IEEE 802.11 broadcast
June 2005
Broadcast
link-local
same as IEEE broadcast
only direct neighbors receive broadcast
mesh-wide
all mesh points receive broadcast
flooded in mesh
RA = DA = broadcast address
SA and broadcast identifier (mesh data frame option) avoid rebroadcast by uniquely identifying frames of same mesh-wide broadcast
jittering of rebroadcast
TTL limits broadcast range
Michael Bahr, Siemens AG, Corporate Technology

21. Beaconing periodic beaconing of mesh points
June 2005
Beaconing
periodic beaconing of mesh points
every dot11sbeaconinterval, jittered
beacon interval contained in beacon interval field
new information elements in beacons
mesh identity
active mesh routing protocol
active mesh routing metrics
mesh security
Michael Bahr, Siemens AG, Corporate Technology

22. Mesh Portal and Interworking
June 2005
Mesh Portal and Interworking
mesh portal is L2 bridge between IEEE s MAC and IEEE 802 MAC
conforms to IEEE 802.1D for IEEE 802 MAC side
address learning at mesh portal
inside, outside, beyond mesh
route discovery
from outside into mesh
RREQ by mesh portal for destination
from inside mesh to outside
mesh portal answers to RREQ
if no RREP, data frame sent to mesh portals
mesh portals relay data frame to all segments
mesh portal learns address and sets up route to source
Michael Bahr, Siemens AG, Corporate Technology

23. Mesh Portal and Interworking
June 2005
Mesh Portal and Interworking
data frame forwarding
data frames for destinations outside mesh or vice versa are tunneled to/from mesh portal
WLAN mesh routing protocol provides information on mesh portal through which destination is reachable
broadcasts transmissions
translation between broadcast mechanisms of mesh and outside mesh
tunneling might be necessary
Michael Bahr, Siemens AG, Corporate Technology

24. Security Based on IEEE 802.11i
June 2005
doc.: IEEE /0593r0
June 2005
Security Based on IEEE i
Key Parts
authentication of mesh points joining a mesh
protected signaling and data traffic based on IEEE i
efficient IEEE i operation in multi-hop mesh environments
Variations
central model using AAA (e.g. RADIUS) and 802.1x if infrastructure available
completely distributed model for stand-alone mesh environments
Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

25. Security Based on IEEE 802.11i
June 2005
doc.: IEEE /0593r0
June 2005
Security Based on IEEE i
Central model
AAA server, 802.1x used to establish PMK between mesh points
Mesh points with direct contact to AAA server are authenticated first
Authenticated mesh points display its status using beacons
Authenticated mesh points authenticate yet unauthenticated neighbors
Distributed model
Pre-shared secrets are distributed to all nodes
PMK and GMK based on these pre-shared secrets
Difference between central / distributed model
Central model provides security/confidentiality among mesh points
Distributed model does not
Focus is protection from outside nodes  both models provide this protection
Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

26. Efficient IEEE 802.11i in Multi-hop Environments
June 2005
doc.: IEEE /0593r0
June 2005
Efficient IEEE i in Multi-hop Environments
Challenge:
802.11i optimized for single hop (AP-client)
Different keys on every link result in cumulative additional computation overhead / delay on multi-hop path
Solution:
PMK for data traffic directly between source and destination
Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

27. Extensibility important feature for IEEE 802.11s routing metrics
June 2005
Extensibility
important feature for IEEE s
routing metrics
variable use of several different, vendor-specific routing metrics
routing protocols
definition of new routing control messages in vendor-specific management frame
mesh identifier in beacons
general purpose column in forwarding table
options field in mesh data frame
flexible extension of mesh data frame
Michael Bahr, Siemens AG, Corporate Technology

28. Summary mainly unmanaged WLAN mesh networks
June 2005
Summary
mainly unmanaged WLAN mesh networks
clients and access points as mesh points
L2-adaptation of AODV (reactive routing protocol) for mesh path selection
contributions to mesh portal / interworking and security
extensible architecture
applicable for many usage scenarios
Michael Bahr, Siemens AG, Corporate Technology

29. June 2005
doc.: IEEE /0593r0
June 2005
Documents of Proposal
11-05/0593r0 p19-presentation-partial-proposal-for-wlan-mesh-networking  this presentation about the proposal
11-05/0592r0 p19-partial-proposal-for-wlan-mesh-networking  the actual proposal on WLAN mesh networking
11-05/0598r0 p19-tgs-checklists  filled in checklists
Michael Bahr, Siemens AG, Corporate Technology
Michael Bahr, Siemens AG, Corporate Technology

30. June 2005
References
[1] IEEE Wireless LAN Edition – A compilation based on IEEE Std ™-1999 (R2003) and its amendments; IEEE Standards Information Network, IEEE Press
[2] Charles Perkins, Elizabeth Belding-Royer, Samir Das: Ad hoc On-Demand Distance Vector (AODV) Routing; IETF RFC 3561 (Experimental), July 2003
[3] IEEE P802.11e/D13.0: Amendment : Medium Access Control (MAC) Quality of Service Enhancements; January 2005
[4] 11-04/54r2 “PAR for IEEE ESS Mesh”
[5] 11-04/56r1 “Five Criteria for IEEE ESS Mesh”
[6] 11-04/1430r12 „Call for Proposals for IEEE s“
[7] 11-04/1174r13 „Functional Requirements and Scope for IEEE s“
[8] 11-04/1175r10 „Comparison Categories and Informative Checklists for IEEE s“
[9] 11-04/662r16 „Usage Models for IEEE s“
[10] 11-04/1477r4 „Terms and Definitions for s“
[11] IEEE Std i™-2004: i™ - Amendment 6: Medium Access Control (MAC) Security Enhancements
Michael Bahr, Siemens AG, Corporate Technology