UM-OLSR OLSR routing protocol in NS2

1. UM-OLSROLSR routing protocol in NS2 郭祐暢 695430044

2. Outline • Brief overview of OLSR • MPR selection algorithm • UM-OLSR install • Example • UM-OLSR code

3. Table driven Source-Initiated On demand DSDV CGSR OLSR TBRPF AODV DSR LMR TORA ABR SSR Ad Hoc Routing Protocols Classification reactive proactive

4. OptimizedLinkStateRoutingProtocol • Proactive & Table-driven • Link State Routing • Each node expands a spanning tree • Each node can obtain the whole network topology • Utilizes a technique to reduce message flooding • MultiPoint Relaying (MPR)

5. 24 retransmissions to diffuse a message up to 3 hops Retransmission node OptimizedLinkStateRoutingProtocol • Each node periodically floods status of its links • Each node re-broadcasts link state information received from its neighbors • Each node keeps track of link state information received from other nodes • Each node uses above information to determine next hope to each destination

6. 11 retransmission to diffuse a message up to 3 hops Retransmission node - MPR OptimizedLinkStateRoutingProtocol • Only selected neighbors(MultiPointRelays,MPRs)retransmitmessages • Select MPRs such thatthey cover all 2hopneighbors • 2-hopneighbors takenfrom neighbors' HELLOmessages

7. OptimizedLinkStateRoutingProtocol • Three main modules • Neighbor/link sensing • Provide topology information up to two hops • MPR selector information notification (“A select B as A’s MPR” in HELLO message to B) • Optimized flooding/forwarding • MPR set to cover all the two hop neighbors • MPR selector set: set of nodes that select me as one of their MPR set • OLSR-Messages from MPR selector set are to be forwarded • Link-State messaging and route calculation • Topology table • Route table

8. B MPR selection • Each node select a set of MPR Selectors • Who can be a MPR Selectors of node N ? • one-hop neighbors of N • MPR set of Node N (Rules) • Set of MPR’s is able to transmit to all two-hop neighbors • Link between node and it’s MPR is bidirectional. Y N X M D Z A

9. Multipoint Relays (MPR) • 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

10. MPR selection algorithm • Each point u has to select its set of MPR. • Goal : Select in the 1-neighborhood of u (N1(u)) a set of nodes as small as possible which covers the whole 2-neighborhood of u(N2(u)). • Step 1: Select nodes of N1(u) which cover isolated points of N2(u). • Step 2: Select among the nodes of N1(u) not selected at the first step, the node which covers the highest number of points of N2(u) and go on till every points of N2(u) are covered.

11. MPR selection algorithm • First step: Select nodes in N1(u) which cover “isolated points” of N2(u). u

12. MPR selection algorithm • Second step : Consider in N1(u) only points which are not already selected at the first step NPR1(u) and points in N2(u) which are not covered by the NPR1(u) . While there exists points in N2(u) not covered by the selected MPR, select in N2(u), the node which covers the highest number of non-covered nodes in N2(u). u

13. MPR selection algorithm • Final：MPRs u

14. Installation • Download UM-OLSR 0.8.8 from http://masimum.dif.um.es/?Software:UM-OLSR • Ns2.27、2.28、2.29 / UM-OLSR 0.8.7、0.8.8 • Copy um-olsr-0.8.8.tgz to ns-allinone-2.29/ns-2.29/ • $ cd ns-allinone-2.29/ns-2.29/ $ tar zxvf um-olsr-0.8.8.tgz $ ln -s ./um-olsr-0.8.8 ./olsr $ patch -p1 < olsr/um-olsr_ns-2.29_v0.8.8.patch $ ./configure $ make

15. Example • Download olsr_example.tcl from http://masimum.dif.um.es/um-olsr/olsr_example.tcl

16. OLSR • Hello message one hop for • Two hop topology information • MPRs • Transmit two hop top topology information • By MPRs • TC message • Complete Topology Information • Shortest Path Tree calculation (Dijkstra) • Routing table build

17. TC message • 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

18. Topology Table MPR Selector in the received TC message Last-hop node to the destination. Originator of TC message

19. TC message • 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

20. 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

21. UM-OLSR File List (Header) • OLSR.h • header file for OLSR agent and related classes • OLSR_pkt.h • contains all declarations of OLSR packets and messages • OLSR_printer.h • includes all printing functions related to OLSR • OLSR_repositories.h • defined all data structures needed by an OLSR node • OLSR_rtable.h • header file for routing table's related stuff • OLSR_state.h • declares and defines internal state of an OLSR node

22. UM-OLSR File List • OLSR.cc • Implementation of OLSR agent and related classes • OLSR_printer.cc • Printing functions used for debugging and tracing are implemented in this file • OLSR_rtable.cc • Implementation of our routing table • OLSR_state.cc • Implementation of all functions needed for manipulating the internal state of an OLSR node