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Doc.: IEEE 802.11-07/2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 1 Mesh points that do not forward Date: 2007-09-17 Authors:

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1 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 1 Mesh points that do not forward Date: Authors:

2 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 2 Abstract This submission describes a mechanism that allows low complexity devices to join a Mesh network without a full implementation of HWMP

3 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 3 Background Tuesday May 15 th discussion resulted in submission of 11-07/732r0 “resolution of LWMP CIDs” Result was mostly elimination of LWMPs from the draft Null Routing (the path selection protocol [sic] associated with LWMPs) remains! Impetus to keep meshes clean (one ID, one protocol, one metric etc.) –Separate beacon? Separate action frame? –ToDS, FromDS = 1  Mesh Data

4 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 4 What is this “special” MP supposed to be? Impetus for dealing with battery-operated (or energy- efficient) devices: –Concerns over footprint/complexity of full-fledged HWMP –“Obligation” to participate in path selection Burden of maintaining forwarding tables (memory) –“Obligation” to forward frames Power consumption burden (Tx and CPU)

5 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 5 Null Path Selection Null Path Selection does a disservice to the Mesh in general and to the Mesh Point in particular –Mesh is not cognizant of the MP –MP is not cognizant of the Mesh Authors believe Null Path Selection makes mesh operation more complex and that a simple solution is available –Pros of null routing No routing implementation required on terminal device –Cons of null routing Proprietary implementation of dual-function MP at the junction of two networks Proprietary implementation of next hop selection on terminal device No guarantee of collaboration between terminal device and dual-function MP!

6 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 6 Unavoidable fact There will be non forwarding devices that send traffic through the mesh –The questions are: who and how? non entity STA MP MPP MP MAP MP STA MP Well documentedUndocumented!?Well documented

7 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 7 Null routing and non forwarding NR F F FF F F F F NF Independent links (no path selection) Real paths (links selected based on an end-to-end metric) NR: Null Routing NF: Non-forwarder F: Forwarder NF

8 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 8 Proposed changes to the draft Add one paragraph explaining the purpose Add 5 conditions allowing MPs to ignore IEs/conditions that would “force” them into becoming forwarders –The real problem is that processing IEs “properly” identifies these MPs as being forwarders from the other MPs’ point of view Too simple to work?

9 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 9 Practical example A E C H F I D B J G K Reference MP Forwarding MP NF MP Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM 9

10 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 10 Practical example A E C H F I D B J G K MP E wishes to communicate with MP A Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM Bcast PREQ 10 Reference MP Forwarding MP NF MP

11 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 11 Practical example A E C H F I D B J G K Receiving MPs establish a path to the source Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM Bcast PREQReverse path is established EE1 11 Reference MP Forwarding MP NF MP Path is not established

12 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 12 Practical example A E C H F I D B J G K Other MPs propagate the path request Paths are established selectively Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM EE1 Bcast PREQReverse path is established CC1CC1 12 Reference MP Forwarding MP NF MP not sent not established

13 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 13 Practical example A E C H F I D B J G K Once the destination is found, the forward path is created Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM EE1 CC1CC1 Forward path is established AA1 Ucast PREP EC2 13 Reference MP Forwarding MP NF MP

14 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 14 Practical example A E C H F I D B J G K Once the destination is found, the forward path is created Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM EE1 CC1CC1 AA1 EC2 Ucast PREP Forward path is established AC2 CC1 14 Reference MP Forwarding MP NF MP

15 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 15 Practical example A E C H F I D B J G K Mesh Point E Dest.NH Mesh Point C Mesh Point AMesh Point B MDest.NHM Dest.NHMDest.NHM EE1 CC1CC1 AA1 EC2 Eventually, bidirectional paths are formed AC2 CC1 15 Reference MP Forwarding MP NF MP

16 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 16 What if MP E is a Null Routing entity? A E C H F I D B J G K E will select an MP to send its traffic to C, H and J do not know how to tell E how good their path is E has to establish a peer link with C, H or J—although it does not implement their primary path selection protocol 16 Reference MP Forwarding MP NF MP ? ??

17 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 17 Conditions for generating HWMP IEs MPTerminal MP PREQ Case A: Original Transmission (Path Discovery) Case B: Original Transmission (Path Maintenance) Case C: Root Path Confirmation Case D1: PREQ Forwarding (no PREP generation)  Case D2: PREQ Forwarding (PREP generation as intermediate MP)  Case E: Proactive PREQ (original transmission)  PREP Case A: Original transmission Case B: PREP Propagation  Case C: Intermediate reply  Case D: Gratuitous PREP PERR Case A: Original transmission  Case B: PERR propagation  RANN Case A: Original transmission  Case B: Forwarding 

18 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 18 MP responsibilities MPTerminal MP PREQ 1. Record (if dest) 2. Update forwarding information (if dest) 3. Initiate RREP (if dest) 4. Proxy (if dest) 5. Intermediate reply  6. Reply and forward  7. Precursor list  PREP 1. Record (if orig) 2. Record dependents  3. Propagate  4. Record proxy at originator (if orig) 5. Record proxy at intermediate node  6. Update precursors  PERR 1. Update records 2. Update route 3. Transmit RERR  RANN 1. Propagate  2. Establish path 3. Record

19 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 19 Terminology Heard in TGs: –“Leaf node” –“Mesh station” –“Non forwarding MP” –“Parasitic MP” –“Selfish MP” –“Terminal MP” –“Lightweight” –“Low complexity”

20 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 20 Conclusion The Mesh Point that does not forward only performs the following: 1.Send a PREQ to whichever destination it would like to establish a path with 2.Process PREPs that are specifically addressed to itself (as a consequence of step 1.) Select the PREP with the best metric and the correct sequence number 3.Respond to PREQs that specifically address the terminal MP (or its proxies) as a destination (within implementation limits) Sometimes the response will based on the value of the path selection metric 4.Keep track of its own sequence number 5.Keep track of the sequence number of its destinations (within the constraints of step 3.) 6.Store a next hop, a metric, a lifetime, a sequence number for each of its destinations (within the constraints of step 3.)

21 doc.: IEEE /2555r0 Submission September 2007 Guenael Strutt, MotorolaSlide 21 References Normative text: r0


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