Thesis Presentation
Routing Overheads within Mobile Ad-Hoc
Networking
Supervisor: Dr. Grant Wigley
By. Christopher Totani
Question and reasons for research
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Mobile Ad Hoc Networking (MANET)
Structure-less network
DSTO working with UniSA in research in this field
Focus on routing overheads for MANETs
Looking at tradeoffs between routing overheads and
end-to-end connectivity
Must work in low bandwidth speeds (nearly dial up
speed) with harsh terrain
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Routing in Networks
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Route traffic between networks & sub networks
Layer 3 (Network Layer)
Usually core of network
Typically through Routers and Layer 3 Switches
Use routing protocol to route traffic
Typically contains networks/sub networks, network
topology, next hop
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Distance Vector Protocols (EIGRP, RIP, BGP)
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Shares metric to calculate routes (i.e. Number of Hops)
Link State protocols (IS-IS, OSPF)
Shares whole routing table
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Structured Networks
Static network design utilising specialised
equipment (Routers, switches, WLAN Gateways)
Advantages
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Stable topology
Devices dedicated towards routing
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Why they are not recommended for military use
Too costly (will need satellite networks)
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Satellite equipment costs $$
Needs staff to manage and configure network
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Single point of connection to network
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Ad-Hoc Network
“ad-hoc” based on latin term meaning “for this
purpose”
Networking with no network specific devices
E.g. routers and switches
Different types of Ad-Hoc Networking
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Mobile Ad-Hoc Networks
Vehicle Ad-Hoc Networks
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Mobile Ad Hoc Networks
Mobile, wireless ad-hoc infrastructure network
Self configuring, Self repairing with little
maintenance overheads
Usually used in scenarios, where structure is too
costly or impossible
However, low bandwidth and poor reliability
Uses special MANET protocols
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Too many overheads with current routing
protocols(E.g. OSPF floods packets)
Not common practice for routers to communicate
between each other via wireless
Some attempts at trying to get them to work within
MANETS
Some are still up for debate
E.g. OSPF – Suggestions of reducing LSA floods
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MANET Structure
Source: Aidarus Mohamed Ibrahim ,UTM: Mobile Ad Hoc Networks(MANETS). 2014.Aidarus
Mohamed Ibrahim ,UTM: Mobile Ad Hoc Networks(MANETS).
http://aidarusjirde.blogspot.com.au/2011/05/mobile-ad-hoc-networksmanets.html
Structured Network
Source: http://stackoverflow.com/questions/7859318/networkingrip-routing-wan-connection-in-packet-tracer
Structured Satellite Network
Source:
http://www.globalsecurity.org/military/library/policy/army/fm/1124/fig7-1.gif
Routing Overheads
Resources required for routing
High routing overheads can affect bandwidth and
energy consumption
However, overheads needed for a stable network
What can influence overheads, as found in
literature
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Number of Neighbours
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Nodes receive more routing updates
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Number of Hops
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Not so much an overhead, but a performance indicator
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Route Discovery and Positioning
Frequency of Updates /Topology Changes
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End to end connectivity
In the context of this thesis, the quality of the
connection between nodes
Poor routing can affect connectivity between nodes
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Packet losses
Poor routing paths
Delay in packet delivery
Poor utilisation of bandwidth
The features of a routing protocol can also affect End to End
Connectivity
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Quality of Service (QoS)
Feature of prioritising packets
Typically prioritises real time packets (e.g. VoIP) over non real
time (e.g. web page)
Better use of bandwidth
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Flat MANET Protocols
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Reactive Protocols (On-Demand routing)
AODV (Ad-hoc On-Demand Distance Vector)
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Topology information transmitted on demand
Uses Route request (RREQ) and route reply (RREP)
Sequence numbers used for topology version
Low overheads, but poor in high mobility situation
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DSR (Direct Source Routing)
Works very similar to AODV
Differs on how it routes packets and lacks sequence numbers
DSR routes whole routing direction
AODV routes next hop
Also differs on how it ‘s beaconless
Tends to have the least routing overheads, but bad performance with
mobility
Flat MANET Protocols
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Proactive Protocols (Continuous update routing)
OLSR (Optimised Link State Routing)
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Link state flooded through the network
Utilise multipoint relays for topology control
Topology control used for maintain topology and hops
Uses hello packets to maintain adjacencies
Higher overheads due to constant routing updates
Supports QoS
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DSDV (Destination-Sequenced Distance Vector)
Works very similar to RIP (uses same Bellman-Ford algorithm)
Has routing table and sequence number of routing table
Updates topology every 30 seconds (as opposed to on demand)
Does have issues with infinite routes
Problems with flat MANET protocols
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Do not scale well
Protocols such as AODV and DSR have problems with packet
delay
Protocols such as OLSR tend to have very high routing
overheads
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Tends to treat all nodes equally
Does not utilise devices full potential
Military uses wide range of devices (Hand held radios to vehicle
mounted radios)
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DSTO MANET Concept
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Divide MANET into smaller MANETS
Create Hierarchies of MANETS
Use larger radio devices mounted on vehicles on higher levels
Use normal radio devices on lower levels
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Hierarchical MANETs
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Divides network into clusters
One device allocated as the “cluster head” per cluster
Cluster head is aware of other clusters within MANET
Also puts nodes in hierarchies
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Many papers have preference to this type
Alternative towards flat topology MANETs
Reduces routing tables and hops for nodes
Allows better utilisation of heterogeneous devices
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Hierarchical Protocols Examples
HOLSR (Hierarchical Optimised Link State
Routing)
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Based on OLSR protocol (utilises multipoint relays,
hello messages and topology control)
HOLSR divides into clusters and levels
Different levels help determine nodes suitability
within a network (Level 3 powerful node, Level 1 not
so powerful)
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Example of Hierarchical structure (HOLSR)
Source: Wang, M., et al. (2007). Comparison of Two Hierarchical Routing Protocols for
Heterogeneous MANET Defence R&D Canada -- Ottawa: 44.
Structured Routing protocols on
MANETS
Popular routing protocols (i.e. OSPF) not in good
state for MANETS
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Tend to do too many adjacencies
Needs to maintain lots of adjacencies
Current state floods too many LSA packets
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OSPF-MDR
Restructures OSPF for MANET use
Uses MANET Designated Routers (MDR) as gateway
for each area
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Like BDRs on OSPF networks
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MDRs form Area 0
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Also known as Connected Dominating Set (CDS)
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Different levels of hello packets to reduce packet
overheads
Appears to be single-hop to MDR
Only tested with up to 200 nodes
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OSPF vs OSPF-MDR MANET Topology
Research Question
What are the tradeoffs between end to end
connectivity vs. routing overheads with
hierarchal mobile ad hoc networks, within the
context of urban military use?
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Methodology
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System – Use simulation
Sampling and Population
Sample size: close to DSTO specifications
Simulate wireless in unreliable terrain
Population: Mobile combatants, mobile vehicles
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Data Collection
Define metrics of Routing Overheads
Collect from different scenarios
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Data Analysis
Look for patterns within protocol metrics
See if data is accurate
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Tools
NS-2 (Free simulator), Quagga
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Methodology
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System – Use simulation
Sampling and Population
Sample size: close to DSTO specifications
Simulate wireless in unreliable terrain
Population: Mobile combatants, mobile vehicles
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Data Collection
Define metrics of Routing Overheads
Collect from different scenarios
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Data Analysis
Look for patterns within protocol metrics
See if data is accurate
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Tools
NS-2 (Free simulator), Quagga
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Methodology
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System – Use simulation
Sampling and Population
Sample size: 16 (Section), 32, 64(Platoon), 128 , 255 (Company)
Determine where hierarchy should start (16, 64)
See protocol stability where larger fails (64, 255)
Flat terrain (Unreliable terrain out of scope)
Population: Mobile combatants
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Data Collection
Collect from different scenarios and size of MANET
Scenarios will differ by movement model
Calculate performance and routing overhead with data from
simulations
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Data Analysis
Look for patterns within protocol metrics
See if data is accurate
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Methodology
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Tools
Operating System – Lubuntu 14.04 (32-bit)
NS-2 v2.35
NAM 1.14
Bonnmotion 2.38 (Create scenario)
AWK scripting language
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Steps to Methodology
Step 1 – Review literature and determine
overheads
Step 2 – Specify metrics of routing overheads
Step 3 – Finalise routing protocols to be simulated
Step 4 – Simulate routing protocol under different
scenarios
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Differ from size of network and movement model
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Step 5 - Map data to meaningful diagrams/tables,
draw conclusions from data gathered.
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Routing Overhead Metrics
Quite difficult to compare based on individual
overheads
E.g. Comparing routing updates – Not all
protocols use hop count (e.g. OLSR)
Many papers just compare Routing Control
packets vs. packets sent
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Routing overhead
Number of control packets sent
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Normalised routing overhead
Number of control packets / Number of packets
sent
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Performance/End to End connectivity
Metrics
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Average Hop Count
Average number of nodes a data packet travel through to reach
destination
Lower is better
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Throughput (Kbps)
Total bandwidth utilised for data packets
Can be an indicator of routing overhead
Higher figures are better
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Average End to End Delay (seconds?)
Time taken: Source  Destination
Less time is better
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Packet Delivery Ratio (% Packets received)
No. packets delivered/No. packets sent
Higher is better
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Routing Protocols to be simulated Preface
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Only using protocols freely available as source code
Very difficult to modify/create routing protocols
in time frame
This alone has dramatically changed how the
thesis is structured
Following protocols wont be simulated
H-OLSR (Source not freely available)
OSPF-MDR (Simulator different)
OSPF, RIP (Not freely available, needs MANET
extensions to work)
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Routing Protocols to be simulated Preface
Protocols chosen are well known MANET routing
protocols
We use simulations to answer several questions
Where should the hierarchy start?
What performance drops do we see when the
network is scaled up?
What trade-offs do we see between routing
overheads and connectivity?
What protocol is best suited for military use?
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Routing Protocols to be simulated
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AODV
DSR
DSDV
OLSR
NS-2 parameters
Channel
Prop
Netif
Mac
Ifq
Channel
Propagation
Network Interface
Mac Layer
Interface Priority Queue
ll
Ant
Link Layer
Antenna
x
y
ifqlen
seed
nn
stop
Mc
x-co-ordinate size (pixels?)
y-co-ordinate size (pixels?)
Size of interface priority queue
Random seed no.
Number of nodes
Time of simulation (seconds)
Maximum Connections
Physical/Datalink Layer
Channel/WirelessChannel
Propagation/TwoRayGround
Phy/WirelessPhy
Mac/802_11
Queue/DropTail/PriQueue (CMUPriQueue for
DSR)
LL
Antenna/OmniAntenna
Scenario
1000, 1500, 2000, 4000, 8000
1000, 1500, 2000, 4000, 8000
100
0.0
16,32, 64, 128,256
100
8, 16, 32, 64, 128
Traffic
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Generated using NS-2’s traffic generation tool
CBR over UDP
Simple traffic
Set to send 2-6kbps (estimated) traffic per
connection
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Movement Model
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Random Waypoint
Most commonly used
Nodes put at random points
Nodes move in zigzag direction
Movement expressed as: Pi to Pi+1
Nodes also pauses at specific random times
Other Movement models
Guass-Markov model (variable speed and
direction)
Disaster area model (Tries to replicate disaster
scenario)
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Normalised Routing Load
Normalised Routing Load
Normalised Routing Load
50
45
40
35
30
25
20
15
10
5
0
AODV
DSR
DSDV
OLSR
16
0.0794
0.0794
0.1852
0.8508
32
1.1187
0.6836
0.6491
2.897
64
1.3004
1.2064
0.7782
3.884
128
5.578
4.0186
7.6448
12.3089
256
4.4232
4.8402
7.2245
43.9886
Packet Delivery Ratio
Packet Delivery Ratio
Packet Delivery Ratio
120.00%
100.00%
80.00%
60.00%
40.00%
20.00%
0.00%
AODV
DSR
DSDV
OLSR
16
95.62%
97.35%
69.35%
87.26%
32
42.94%
44.14%
30.74%
37.85%
64
45.35%
47.69%
34.46%
41.15%
128
18.00%
17.66%
4.15%
15.89%
256
2.61%
2.55%
2.60%
2.67%
End to End Delay
End to End Delay
1.8
End to End Delay (s)
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0
AODV
DSR
DSDV
OLSR
16
0.2406
0.4505
0.0193
0.0174
32
0.2002
0.2876
0.0182
0.0133
64
0.2546
1.1283
0.0143
0.0189
128
0.3779
1.5715
0.0129
0.0492
256
0.0065
0.0068
0.0066
0.0065
Summary of results
At 16 nodes, performance is quite optimal (Though
32 nodes shows adequate performance besides
PDR)
16 nodes per lower level MANET should help
prevent MANETs merge to larger ones
128 and 256 nodes shows little to no routing
activity
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Summary of results
AODV and DSR shows similar performance (Good
PDR and Overheads, Bad delay as network
increases, esp. DSR)
DSDV shows lowest routing overheads, but poor
PDR (even at 16 nodes)
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Quite contrary to claims of DSDV having high overheads
Possible AODV and DSR routing overheads higher due to
movement?
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OLSR shows good performance through all
performance metrics. However, very high routing
overheads at more than 64 nodes
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Summary of results
Despite high overheads at larger sized MANETs,
OLSR favoured
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Has well document hierarchical extension
Supports QoS
Performs well through all performance metrics
Routing overheads become a problem with larger network
AODV second favoured
Lower overhead, performed consistently well
No QoS or well documented Hierarchical implementation
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Simulations not finished yet
Still need simulations for other movement models
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