1. Qamar A TararOLSR Protocol1 Optimized Link State Routing Protocol for Ad Hoc Networks Qamar Abbas Tarar “Mobile ad-hoc networks based on wireless LAN”

2. Qamar A TararOLSR Protocol2 Problems in MANETs  Scalability  QoS  Security  Interoperation with the Internet  Limited Battery Life  Node Mobility  Unreliable radio channel Hidden terminal problem  Route maintenace  Unpredictable link properties

3. Qamar A TararOLSR Protocol3 Unicast-Routing Protocol for MANET (Topology-based) Table-Driven/ Proactive HybridOn-Demand- driven/Reactive Clusterbased/ Hierarchical Distance- Vector Link- State ZRPDSR AODV TORA LANMAR CEDAR DSDVOLSR TBRPF FSR STAR MANET: Mobile Ad hoc Network (IETF working group) Classification of Routing Protocols for MANETS CBRP

4. Qamar A TararOLSR Protocol4 Proactive vs Reactive Routing Protocols  Proactive Routing Protocols (DSDV, OLSR) + Routes to all reachable nodes in the network available. + Minimal initial delay for application. - Larger signalling traffic and power consumption.  Reactive Routing Protocols (DSR, CBR etc) + Smaller signalling traffic and power consumption. - A long delay for application when no route to the destination available

5. Qamar A TararOLSR Protocol5 Structure OLSR  Overview  Multipoint relays  Neighbor sensing  MPR selection  MPR information declaration  Routing table calculation  Extensions in OLSR  Conclusions

6. Qamar A TararOLSR Protocol6 Overview  OLSR  Developed by IETF  Table driven  Inherits Stability of Link-state protocol  Selective Flooding  Periodic Link State Information generated only by MPR  MPRs employed for optimization

7. Qamar A TararOLSR Protocol7 Link State Routing (eg, OSPF)  Each node periodically floods status of its links  Each node re-broadcasts link state information received from its neighbour  Each node keeps track of link state information received from other nodes  Each node uses above information to determine next hope to each destination 24 retransmissions to diffuse a message up to 3 hops Retransmission node

8. Qamar A TararOLSR Protocol8 OLSR Overview  In LSR  protocol a lot of control messages unnecessary duplicated  In OLSR  only MPR retransmit control messages:  Reduce size of control message;  Minimize flooding  Other advantages (the same as for LSR):  As stable as LSR protocol;  Proactive protocol(routes already known);  Does not depend upon any central entity;  Tolerates loss of control messages;  Supports nodes mobility.  Good for dense network

9. Qamar A TararOLSR Protocol9 Optimized Link state routing (OLSR) 24 retransmissions to diffuse a message up to 3 hops Retransmission node 11 retransmission to diffuse a message up to 3 hops Retransmission node

10. Qamar A TararOLSR Protocol10 Description of OLSR  MPR (Multipoint relays)  MPR selector  Symmetric 1-hop neighbours  Symmetric strict 2-hop neighbours D S B M X Y Z P A

11. Qamar A TararOLSR Protocol11 Neighbor sensing  Each node periodically broadcasts Hello message:  List of neighbors with bi-directional link  List of other known neighbors.  Hello messages permit each node to learn topology up to 2 hops  Based on Hello messages each node selects its set of MPR’s

12. Qamar A TararOLSR Protocol12 Example of neighbor table One-hop neighbors Neighbor’s idState of Link BBidirectional GUnidirectional CMPR …… Two-hop neighbors Neighbor’s idAccess though EC D C …… Also every entry in the table has a timestamp, after which the entry in not valid

13. Qamar A TararOLSR Protocol13 Multipoint Relays (MPR) N  Reduce re-transmission in the same region  Each node select a set of MPR Selectors  MPR Selectors of node N - MPR(N) - one-hop neighbors of N

14. Qamar A TararOLSR Protocol14 Multipoint Relays (MPR) N  Reduce re-transmission in the same region  Each node select a set of MPR Selectors  MPR Selectors of node N - MPR(N) - one-hop neighbors of N  MPR set of Node N  Set of MPR’s is able to transmit to all two-hop neighbors  Link between node and it’s MPR is bidirectional.

15. Qamar A TararOLSR Protocol15  Every node keeps a table of routes to all known destination through its MPR nodes  Every node periodically broadcasts list of its MPR Selectors (instead of the whole list of neighbors).  Upon receipt of MPR information each node recalculates and updates routes to each known destination Multipoint Relays (MPR)

16. Qamar A TararOLSR Protocol16 MRP selection in OLSR Node 1 Hop Neighbors 2 Hop Neighbors MPR(s) B A,C,F,G D,E C  Available BW  OLSR: node B will select C as its MPR So all the other nodes know that they can reach B via C 30 100 50 110 25 60 10 40 5 10  D->B route is D-C-B, whose bottleneck BW is 3 3

17. Qamar A TararOLSR Protocol17 MRP selection in OLSR Node 1 Hop Neighbors 2 Hop Neighbors MPR(s) B A,C,F,G D,E C  Available BW  OLSR: node B will select C as its MPR So all the other nodes know that they can reach B via C 30 100 50 110 25 60 10 40 5 10  D->B route is D-C-B, whose bottleneck BW is 3 3  Optimal route (i.e., path with maximum bottleneck bandwidth: D-F-B (bottleneck bandwidth of 10)

18. Qamar A TararOLSR Protocol18 Multi-Point Relays/routers Passes Topology Information Acts as router between hosts Minimizes information retransmission Forms a routing backbone

19. Qamar A TararOLSR Protocol19 Structure of an OLSR Network MPRs form routing backbone Other nodes act as “hosts”

20. Qamar A TararOLSR Protocol20 Structure of an OLSR Network MPRs form routing backbone Other nodes act as “hosts” As devices move

21. Qamar A TararOLSR Protocol21 Structure of an OLSR Network MPRs form routing backbone Other nodes act as “hosts” As devices move Topological relationships change Routes change Backbone shape and composition changes

22. Qamar A TararOLSR Protocol22 MPR information declaration  TC – Topology control message:  Sent periodically. Message might not be sent if there are no updates and sent earlier if there are updates  Contains:  MPR Selector Table  Sequence number  Each node maintains a Topology Table based on TC messages  Routing Tables are calculated based on Topology tables

23. Qamar A TararOLSR Protocol23 Topology Table Destination address Destination’s MPR MPR Selector sequence number Holding time MPR Selector in the received TC message Last-hop node to the destination. Originator of TC message

24. Qamar A TararOLSR Protocol24 Topology Table (cont)  Upon receipt of TC message:  If there exist some entry to the same destination with higher Sequence Number, the TC message is ignored  If there exist some entry to the same destination with lower Sequence Number, the topology entry is removed and the new one is recorded  If the entry is the same as in TC message, the holding time of this entry is refreshed  If there are no corresponding entry – the new entry is recorded

25. Qamar A TararOLSR Protocol25 Routing Table  Each node maintains a routing table to all known destinations in the network  Routing table is calculated from Topological Table, taking the connected pairs  Routing table:  Destination address  Next Hop address  Distance  Routing Table is recalculated after every change in neighborhood table or in topological table

26. Qamar A TararOLSR Protocol26 Extensions in OLSR  Qos OLSR  Fast OLSR  Towards IPv6 OLSR  Power saver mode  Change in the contents of TC packet

27. Qamar A TararOLSR Protocol27 QoS Routing: Difficulties in QoS routing Due to mobility  Availability and manageability of Link state metrics  Link quality changes quickly and continuously  Computational cost and protocol overhead affect the performance of the QoS routing protocol  Protocol performance evaluation is complex

28. Qamar A TararOLSR Protocol28 Proactive QoS Routing  Advantages  suitable for the unpredictable nature of Ad-Hoc networks  suitable for the requirement of quick reaction to QoS demands  makes call admission control possible  avoids the waste of network resources  Disadvantages  introduces additional protocol overhead  trade-off between the QoS performance and traditional protocol performance But.. Little work has been done to analyse the impact of the additional overhead on pro-active QoS routing

29. Qamar A TararOLSR Protocol29 QoS Versions of OLSR 30 100 50 110 25 60 10 40 5 10  OLSR protocol does not guarantee to find the best bandwidth route  3 heuristics are proposed to enhance OLSR in bandwidth aspect  The heuristics select good bandwidth neighbour as MPR 3

30. Qamar A TararOLSR Protocol30 QoS Versions of OLSR  OLSR_R1: similar to OLSR (i.e., choose 1-hop neighbours that cover max. number of 2-hop neighbours), tie-breaker now max BW Node 1 Hop Neighbors 2 Hop Neighbors MPR(s) B A,C,F,G D,E C  OLSR_R2: select the best BW neighbors as MPRs until all the 2-hop neighbors are covered. Node 1 Hop Neighbors 2 Hop Neighbors MPR(s) B A,C,F,G D,E F  OLSR_R3: selects the MPRs in a way such that all the 2-hop neighbors have the max. bottleneck BW path through the MPRs to the current node. Node 1 Hop Neighbors 2 Hop Neighbors MPR(s) B A,C,F,G D,E A,F 30 100 50 110 25 60 10 40 5 10 3

31. Qamar A TararOLSR Protocol31 Evaluation of QoS OLSR  Simulation: generate networks, run OLSR algorithms, compare results against paths calculated by Link-State algorithm (i.e. complete knowledge, all-pair shortest path)  Network area: 1000 M  1000 M  Number of nodes: 100  Transmission range: 100 M, 200 M, 300 M  Bandwidth: assigned randomly  Results are averaged over 100 randomly generated networks

32. Qamar A TararOLSR Protocol32 Performance Metrics Error rate: percentage of routes with non-optimal bandwidth Average difference: for routes with non-optimal bandwidth, how far off the optimal bandwidth are we Overhead: the average number of control messages transmitted per node MPR count: average number of MPRs in the network

33. Qamar A TararOLSR Protocol33 Experimental Results AlgorithmTransmissi on Range PerformaceCost Error Rate Average differenceOver- head MPR Count Standard OLSR 300 M28%46%1265 200 M41%51%2468 100 M12%45%542 OLSR_R1 300 M14%22%1265 200 M21%26%2468 100 M8%44%542 OLSR_R2 300 M0% 1870 200 M0% 3372 100 M0% 5.745 OLSR_R3 300 M0% 2671 200 M0% 3873 100 M0% 5.744 Pure Link State Algorithm 300 M0% 1245100 200 M0% 979100 100 M0% 28100

34. Qamar A TararOLSR Protocol34 Fast OLSR  Due to Proactive nature,routes available when needed However  In dense network, due to fast node Mobility, links valid only for short time period.  Hence to minize packet loss,  broken links between node and its neighbors must be quickly detected.

35. Qamar A TararOLSR Protocol35 Neighbor Discovery in Fast OLSR 3-procedures:  Switch to Fast-Moving/Default mode: In Fast mode,send Fast-Hellos and vice versa. A Fast-Hello is smaller than a Hello  Establishing fast Links: A node in Fast-Moving mode sends Fast-Hello messages at high frequency.  Refresh Fast links & Detect new broken links: by sending periodic Fast-Hellos

36. Qamar A TararOLSR Protocol36 Towards IPv6 OLSR  OLSR operate well with both IPv4 and IPv6  To operate with IPv6, the only required change  is to replace the IPv4 addresses with IPv6 address.  The minimum packet and message sizes should be adjusted accordingly, considering the greater size of IPv6 addresses.

37. Qamar A TararOLSR Protocol37 Power saver mode  A node can indicate if it agrees to keep the packets of its neighbors  Any node, who wants to go in sleep mode, will select ONLY that neighbor as MPR who can keep its packets  TC packet will diffuse this info, and all data packets will be routed through that “power saver” node

38. Qamar A TararOLSR Protocol38 Change in the contents of TC packet  Instead of advertising its set of MPRs, a node will list its neighbors who has selected him as an MPR  Many nodes (loosely connected, or at the boundaries) will not be selected MPR any node. So they will not send any TC (25% less overhead)  Less frequent changes in this set

39. Qamar A TararOLSR Protocol39  Advantages  Route immediately available  Reactivity to topological changes can be adjusted by setting the time interval for HELLO messages  Minimize flooding by using MPR  Can be integrated into existing system as it requires no change to IP format  Disadvantages  Bigger overhead  Need more power  Not all allgoritms pubically documented  Needs more operational experience to debug Conclusions

40. Qamar A TararOLSR Protocol40 Readings  G. Pei, M. Gerla, and X. Hong, " LANMAR: Landmark Routing for Large Scale Wireless Ad Hoc Networks with Group Mobility," In Proceedings of IEEE/ACM MobiHOC 2000, Boston, MA, Aug. 2000. LANMAR: Landmark Routing for Large Scale Wireless Ad Hoc Networks with Group Mobility  R. Ogier, F. Templin, M. Lewis, " Topology Dissemination Based on Reverse-Path Forwarding (TBRPF)," IETF Internet Draft, July 28 2003. Topology Dissemination Based on Reverse-Path Forwarding (TBRPF)  Thomas Clausen, Philippe Jacquet, " Optimized Link State Routing Protocol (OLSR)," IETF Internet Draft, July 3 2003. Optimized Link State Routing Protocol (OLSR)  X. Hong, K. Xu, and M. Gerla, " Scalable Routing Protocols for Mobile Ad Hoc Networks " IEEE Network Magazine, July-Aug, 2002, pp. 11-21 Scalable Routing Protocols for Mobile Ad Hoc Networks  Thomas Kunz,Ying Ge, Louise Lamont, “ Quality of Service Routing in Ad-Hoc Networks Using OLSR” Carleton University, CRC,2002  M Benzaid, P Minet and K A Agha, “Integrating fast mobility in the OLSR routing protocol” INRIA, LRI, France,September 2002.

41. Qamar A TararOLSR Protocol41 Q & A