SELFISH NODES IN ADHOC NETWORKS

 Hey All, In this post we discuss about selfish nodes and how to simulate selfish node scenario using ns2. 

MANET is self-constrained network, each node should collaborate with each other to perform functions of the network but sometimes node may behave selfishly to conserve their resource like batter power, bandwidth etc. Such nodes are called selfish node and selfishness disturb the network and take away the network from their regular mission. 

The term selfish node mainly comes from a  specific class of AdHoc Networks known as cooperative networks,  where different autonomous and as well as heterogeneous nodes (possibly owned by different individuals)  form a network and agree to forward each others packet   in cooperative manner.

The biggest problem in this type of network  is "selfish node problem", where some may start dropping the packets of others just for its own benefit (to save the power)

There are two commonly known techniques to with the selfish node problem:  

1. Reputation based
2. Incentive based 
3. The combination of both

This particular area of research is closely related with game theoretic approaches to solve as well analyze the problem.

Selfish node does not forward any data packets to other nodes except itself. Selfish nodes helps to optimize their own gain, with neglect for the welfare of other nodes in a network. Selfish Nodes cooperates during the route discovery cycle to maintain a concise routing table and to be present in other routing tables in a network.

Behavior of selfish nodes

• It does not forward the RREQ messages.
• Do not forward data messages.
• Delayed forwarding RREQ messages.
• Do not forward RREP messages.

Code for Selfish Nodes

#define options
set val(chan) Channel/WirelessChannel
set val(prop) Propagation/TwoRayGround
set val(netif) Phy/WirelessPhy
set val(mac) Mac/802_11
set val(ifq) Queue/DropTail/PriQueue
set val(ant) Antenna/OmniAntenna
set val(ll) LL
set val(ifqlen) 150
set val(nn) 10
set val(rp) DSR
set val(X) 600
set val(Y) 600
set val(cstop) 50
set val(stop) 50
set val(cp) "scen-20-10"

# Initialize Global Variables
set ns_ [new Simulator]

set tracefd [open DSR.tr w] $ns_ trace-all $tracefd
set namtrace [open DSR.nam w] $ns_ namtrace-all-wireless $namtrace $val(X) $val(Y)
#set up top
set topo [new Topography] $topo load_flatgrid $val(X) $val(Y)
# Create God
set god_ [create-god $val(nn)] #create channel
set chan_1_ [new $val(chan)] set chan_2_ [new $val(chan)]

if {$val(rp) == "DSR"
} {

set val(ifq) CMUPriQueue
} else {

set val(ifq) Queue/DropTail/PriQueue
}
#configure nodes
$ns_ node-config -adhocRouting $val(rp) \
-llType $val(ll) \
-macType $val(mac) \
-ifqType $val(ifq) \
-ifqLen $val(ifqlen) \
-antType $val(ant) \
-propType $val(prop) \
-phyType $val(netif) \
-topoInstance $topo \
-agentTrace ON \
-routerTrace ON \
-macTrace ON \
-movementTrace ON \
-channel $chan_1_
# create nodes
for {
set i 0
} {
$i < $val(nn)
} {
incr i
} {

set node_($i) [$ns_ node] $node_($i) random-motion 0;
}
puts "loading random connection pattern..."
source $val(cp)
source "cbr"
#Define initial node position
for {
set i 0
} {
$i<$val(nn)
} {
incr i
} {
$ns_ initial_node_pos $node_($i) 30
}
#$ns_ at 0.0 "[$node_(4) set ragent_] hacker"
for {
set i 0
} {
$i<4
} {
incr i
} {
$ns_ at $val(cstop) "$cbr_($i) stop"
}
for {
set i 0
} {
$i<$val(nn)
} {
incr i
} {
$ns_ at $val(stop).000000001 "$node_($i) reset";
}
$ns_ at 0.01 "$node_(0) add-mark m brown circle"
$ns_ at 0.01 "$node_(1) add-mark m brown circle"
$ns_ at 0.01 "$node_(2) add-mark m brown circle"
$ns_ at 0.01 "$node_(3) add-mark m brown circle"
$ns_ at 0.01 "$node_(4) add-mark m brown circle"
$ns_ at 0.01 "$node_(5) add-mark m brown circle"
$ns_ at 0.01 "$node_(6) add-mark m brown circle"
$ns_ at 0.01 "$node_(7) add-mark m brown circle"
$ns_ at 0.01 "$node_(8) add-mark m brown circle"
$ns_ at 0.01 "$node_(9) add-mark m brown circle"

$ns_ at 40.5 "$ns_ trace-annotate \" NODE 0 IS DETECTED AS SELFISH NODE AT TIME 40.5\""
$ns_ at 45.5 "$ns_ trace-annotate \" NODE 4 IS DETECTED AS SELFISH NODE AT TIME 45.5\""
$ns_ at 45.0 "$ns_ trace-annotate \" NODE 7 IS DETECTED AS SELFISH NODE AT TIME 45.0\""
$ns_ at 45.5 "$ns_ trace-annotate \" NODE 9 IS DETECTED AS SELFISH NODE AT TIME 45.5\""

$ns_ at 40.5 "$node_(0) delete-mark m"
$ns_ at 40.5 "$node_(0) add-mark m red circle"
$ns_ at 48.5 "$node_(4) delete-mark m"
$ns_ at 45.5 "$node_(4) add-mark m red circle"
$ns_ at 48.5 "$node_(7) delete-mark m"
$ns_ at 45.5 "$node_(7) add-mark m red circle"
$ns_ at 48.5 "$node_(9) delete-mark m"
$ns_ at 45.5 "$node_(9) add-mark m red circle"

$ns_ at $val(stop) "finish"
$ns_ at $val(stop).0 "$ns_ trace-annotate \"Simulation has ended\""
$ns_ at $val(stop).00000001 "puts \"NS exiting...\"; $ns_ halt"
proc finish {

} {
global ns_ tracefd namtrace
$ns_ flush-trace
close $tracefd
close $namtrace
exit 0
}
puts "Starting simulation..."
$ns_ run