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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. - PowerPoint PPT Presentation
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Routing in Ad Hoc Networks
Audun Søberg HenriksenTruls Becken
Overview
Short introduction Example of a basic routing algorithm Routing protocols IP configuring Security
Short introduction to wireless multihop networks
Two or more nodes equippedwith wireless communicationsand networking capability
Base station is not necessary A node can communicate directly
with 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.)
Application areas
Tactical military Emergencies Disaster relief Sensor Meetings/conferences
Challenges
Dynamic topologies Bandwidth-constrained, variable
capacity links Energy-constrained Limited physical security Scalability
Simple routing protocol example
Propagation of routing table Routing and transmitting
Routing table
Destination terminal
Nextnode
A AB AC ED D… …
Each terminal has its own routing table(in proactive routing algorithms)
Position notification packet
ID of terminal which the created the packet
Timestamp for the created packet
ID of hop source terminal
Hop count
Contents of the packet:
Used to make and update the Routing Table Broadcasted in a limited area
Renewal of Position Notification Packet
A B D
t =1 t =2 t =3 t =4
A A A B A C
A 1 A 1 A 1 B 2 A 1 C 3
C
B B CC
Routing
A
B
Routing Table in D
D
G
E
I
C
HF
To F
Dest Next
A AB BC ED -E EF IG E
H II I
Routing
A
B
D
G
E
I
C
HF
To F
Routing Table in I Dest Next
A DB DC CD DE EF HG E
H HI -
Routing
A
B
D
G
E
I
C
HF
To F
Routing Table in H Dest Next
A IB IC CD IE IF FG C
H -I I
Basic transmitting procedure
Request to send (RTS) Clear to send (CTS)
Ready to receive (RTR)
Topology problem Hidden terminal problem Exposed terminal problem
Busy tones
Ad Hoc routing protocols
Proactive– Large overhead
Reactive– Delay before first packet– Doesn’t scale
Hybrid scheme– Clusters
Destination Sequenced Distance Vector (DSDV) Periodic routing Distance vector
– dest, next hop, distance, seq no Two ways to update neighbors
– Full dump– Incremental update
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
Ad-hoc On-demand Distance Vector (AODV) From DSR
– Route discovery– Route maintenance
From DSDV– Hop-by-hop routing– Sequence numbers
Zone Routing Protocol (ZRP)
Predefined zones– Centered around each node
Proactive local routing Reactive global routing
IP address assignment
No centralized logic Small address room in IPv4 Network splitting Network merging
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
Routing security vulnerabilities
Open medium Dynamic topology Distributed cooperation
(absence of central authorities) Constrained capability
(energy)
Types of attacks
Black hole Denial of service Routing table overflow Impersonation Energy consummation
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