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Routing in Ad Hoc Networks

Routing in Ad Hoc Networks. Audun Søberg Henriksen Truls Becken. Overview. Short introduction Example of a basic routing algorithm Routing protocols IP configuring Security. Short introduction to wireless multihop networks.

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Routing in Ad Hoc Networks

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  1. Routing in Ad Hoc Networks Audun Søberg Henriksen Truls Becken

  2. Overview • Short introduction • Example of a basic routing algorithm • Routing protocols • IP configuring • Security

  3. Short introduction to wireless multihop networks • Two or more nodes equippedwith wireless communicationsand networking capability • Base station is not necessary • A node can communicate directlywith another node that is immediately within radio range • To communicate with nodes outside its own radio range an intermediate node is used to forward the packet • The network is self-organizing and adaptive(autonomous distributed control is required) • Nodes are able to detect the presence of other nodes and join them into the network • The nodes don’t need to be of the same type(phone, PDA, laptop, sensor, etc.)

  4. Application areas • Tactical military • Emergencies • Disaster relief • Sensor • Meetings/conferences

  5. Challenges • Dynamic topologies • Bandwidth-constrained, variable capacity links • Energy-constrained • Limited physical security • Scalability

  6. Simple routing protocol example • Propagation of routing table • Routing and transmitting

  7. Routing table • Each terminal has its own routing table(in proactive routing algorithms)

  8. Position notification packet • Used to make and update the Routing Table • Broadcasted in a limited area Contents of the packet:

  9. Renewal of Position Notification Packet A B D C A A B A C A B B C C t =3 t =1 t =2 t =4

  10. Routing Table in D Routing G B E C To F D I A F H

  11. Routing Table in I Routing G B E C To F D I A F H

  12. Routing Table in H Routing G B E C To F D I A F H

  13. Basic transmitting procedure • Request to send (RTS) • Clear to send (CTS) • Ready to receive (RTR)

  14. Topology problem • Hidden terminal problem • Exposed terminal problem • Busy tones

  15. Ad Hoc routing protocols • Proactive • Large overhead • Reactive • Delay before first packet • Doesn’t scale • Hybrid scheme • Clusters

  16. Destination Sequenced Distance Vector (DSDV) • Periodic routing • Distance vector • dest, next hop, distance, seq no • Two ways to update neighbors • Full dump • Incremental update

  17. Dynamic Source Routing (DSR) • On demand • Source routing • Each packet contains full route • Route discovery • Flood RREQ packets • RREP returned when route found • Route maintenance • RERR when route is broken

  18. Ad-hoc On-demand Distance Vector (AODV) • From DSR • Route discovery • Route maintenance • From DSDV • Hop-by-hop routing • Sequence numbers

  19. Zone Routing Protocol (ZRP) • Predefined zones • Centered around each node • Proactive local routing • Reactive global routing

  20. IP address assignment • No centralized logic • Small address room in IPv4 • Network splitting • Network merging

  21. Two approaches • A leader • Responsible for all addresses • Buddy system • Start with one node responsible for all addresses • Joining node gets half of the addresses from an existing node

  22. Routing security vulnerabilities • Open medium • Dynamic topology • Distributed cooperation(absence of central authorities) • Constrained capability(energy)

  23. Types of attacks • Black hole • Denial of service • Routing table overflow • Impersonation • Energy consummation

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