A Performance Comparison of Manets Routing Protocols
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Transcript of A Performance Comparison of Manets Routing Protocols
A Performance Comparison of DSDV & AODV Routing Protocols for MANETs
Presented By : Chander Mohan, SSIET DERABASSI, 9996016992
Outline
• Purpose of this work• Wired & Wireless Networks• Introduction to MANETs• Routing in MANETs• Compare Two Protocols
– DSDV– AODV
• Simulation– ns extensions– Protocol implementations
• Simulation results
Purpose of this work
• Wireless ad-hoc networks have gained a lot of importance in wireless communications.
• Wireless communication is established by nodes acting as routers and transferring packets from one to another in ad-hoc networks.
• Routing in these networks is highly complex due to moving nodes and hence many protocols have been developed.
• Table driven (DSDV) & Source on demand (AODV) strategies are compared.
Wired & Wireless Networks
Wired Network• Connected with the help of wires• Very High Speed • Expensive to maintain
Wireless Network
• Connected with the help of Radio Frequencies
• Speed is not very high due to interference, multiple connections.
• Large coverage areaNode
1
Node 3
Node 2
Node1
Node 2
Node 3
Introduction to MANETs
• Wireless network without any pre-existing infrastructure
• Dynamic nature of nodes i.e mobility• Every node act as a router• A MANET can be a standalone network or it
can be connected to external networks like (Internet)
Example of MANET
IEEE 802.11b (WLAN) & MANET
Why Ad Hoc Networks?• Setting up of fixed access points and backbone infrastructure
is not always viable– Infrastructure may not be present in a disaster area or war
zone– Infrastructure may not be practical for short-range radios;
Bluetooth (range ~ 10m)• Ad hoc networks– Do not need backbone infrastructure support– Useful when infrastructure is absent, destroyed or
impractical
Applications• Personal area networking– cell phone, laptop
• Military environment– soldiers, tanks, planes
• Civilian environment– taxi cab network– meeting rooms– sports stadiums– boats, small aircraft
• Emergency operations– search-and-rescue– policing and fire fighting
Challenges in Mobile Environments· Limitations of the Wireless Network
· packet loss due to transmission errors· frequent disconnections/partitions· limited communication bandwidth
· Limitations Imposed by Mobility· dynamically changing topologies/routes· lack of mobility awareness by system/applications
· Limitations of the Mobile Computer· short battery lifetime
Working of MANET
Features of MANETs
• Autonomous Terminal• Distributed Operation• Multi hop Routing• Dynamic Topology
Routing in MANETs
• Routing is the act of moving information from a source to a destination
• Routing involves two activities- Determining optimal routing path- Transferring the packets
Classification of Routing Protocols in MANETs
Table Driven (Proactive)
• The nodes maintain a table of routes to every destination in the network
• Keeping routes to all destinations up-to-date, even if they are not used, is a disadvantage with regard to the usage of bandwidth and of network resources
• Low latency, suitable for real-time traffic
On-demand (Reactive)
• These protocols were designed to overcome the wasted effort in maintaining unused routes, Routing information is acquired only when there is a need for it
• Saves energy and bandwidth during inactivity
• Flooding is used for route discovery
• Significant delay might occur as a result of route discovery
DSDV (Destination Sequenced Distance Vector) Protocol
• Based on Bellman-Ford Routing Algorithm (BFRA)
• Each node maintains a routing table which stores– next hop, cost metric towards each destination– a sequence number that is created by the destination itself
• Each route is tagged with a sequence number; routes with greater sequence numbers are preferred
• When a node decides that a route is broken, it increments the sequence number of the route and advertises it with infinite metric
DSDV (Destination Sequenced Distance Vector) Protocol
• When X receives information from Y about a route to Z– Let destination sequence number for Z at X be S(X), S(Y) is sent from Y
– If S(X) > S(Y), then X ignores the routing information received from Y – If S(X) = S(Y), and cost of going through Y is smaller than the route
known to X, then X sets Y as the next hop to Z– If S(X) < S(Y), then X sets Y as the next hop to Z, and S(X) is updated to
equal S(Y)
X Y Z
AODV (Ad Hoc On-Demand Distance Vector Routing) Protocol
• Route Requests (RREQ) are forwarded to discover a route
• When a node re-broadcasts a Route Request, it sets up a reverse path pointing towards the source
• When the intended destination receives a Route Request, it replies by sending a Route Reply (RREP)
• Route Reply travels along the reverse path set-up when Route Request is forwarded
Route Discovery in AODV
1
2
3
4
5
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7
8
Source
Destination
Propagation of Route Request (RREQ) packet
In case of broken links……
• Node monitors the link status of next hop in active routes
• Route Error packets (RERR) is used to notify other nodes if link is broken
• Nodes remove corresponding route entry after hearing RERR
Route Discovery in AODV
1
2
3
4
5
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7
8
Source
Destination
Path taken by Route Reply (RREP) packet
Simulation
• Network Simulator ns-2.34 based on- Otcl (an object oriented extension of Tcl)- C++
Simulation Scenario
Tcl Script
C++ Implementation
1 2
set ns_ [new Simulator]
set node_(0) [$ns_ node]
set node_(1) [$ns_ node]
class MobileNode : public Node {
friend class PositionHandler;public: MobileNode();
••
}
What we need in one simulation?
• Appearance: the whole topology view of sensor network or mobile network– The position of nodes: (x, y, z) coordinate– The movement parameters
• Starting time• To what direction• Speed
• Internal work: which nodes are the sources? what are the connections? and using what kind of connection?
• Drive the simulation: What about the configuration network components on sensor node? Where to give out the simulation results? How to organize a simulation process?
Simulation Parameters
• Simulation Scenario
Packet Drop in AODV & DSDV at 70 sec
AODV
DSDV
Results & Discussion
• AODV • DSDV
Throughput Analysis
Conclusion
• DSDV routing protocol consume more bandwidth, because of frequent broadcasting of updates
• AODV is much better than DSDV as it results in less overhead and more bandwidth
THANK YOU
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