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First Page
Efficient Routing in Suburban Ad-Hoc Networks
(SAHN)
Muhammad Mahmudul Islam Dr. Ronald Pose Dr.
Carlo Kopp School of Computer Science Software
Engineering Monash University
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Index1
Topics

• Overview of SAHN
• Routing in SAHN (SAHNR)
• Simulation Results
• Future Work
• Current Project Status
• Acknowledgements

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Definition1
What is a SAHN?
An alternative to existing broadband services
for cooperative users using wireless
technology at an affordable cost
SAHN Definition
SAHN Definition
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Why not existing solutions1
Limitations of Existing Wired Services?

• Dialup and high speed services (e.g. cable modems
  xDSL)
• Provide mostly asymmetric bandwidth utilization
• Inadequate for file transfer, X protocol,
  interactive graphical programs etc
• Require costly wiring infrastructure
• Impose service charges
• Not widely available

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Why not existing solutions2
Limitations of Existing Wireless Services?

• Nokia RoofTop and other packet radio schemes
• Mostly centrally controlled
• Provide inadequate QoS
• Not optimized for Ad-Hoc networks

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SAHN Motivation
Limitations of Commercial Services

• Commercial broadband solutions are
• Expensive
• Not universally available
• Provide restricted service
• Commercial service restrictions
• Asymmetric traffic characteristics
• Poor QoS management
• Only supports Internet protocols
• Limited security, management and accounting
  support

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Motivation
Motivation for SAHN (1)

• Provide services not offered by commercial
  service providers
• Bypass expensive infrastructure for broadband
• Provide symmetric bandwidth
• WLAN in inadequate wiring infrastructure
• Bypass ongoing service charges for Telcos
  independent traffic

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Motivation2
Motivation for SAHN (2)

• Feature QoS
• Security throughout all layers
• Utilizing link states (e.g. available bandwidth,
  link stability, latency, jitter and security) to
  select suitable routes
• Avoid selfish routing strategy
• Proper resource access control and management

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SAHN Definition
Properties of SAHN (1)

• Ideal for cooperative nodes. E.g. spread over a
  suburban area, connecting houses and business
• Topology is quasi static
• Uses wireless technology
• Multi-hop QoS routing
• Decentralized
• Symmetric broadband, multi Mbits/sec bandwidth
• Security

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SAHN Definitio2
Properties of SAHN (2)

• No charges for SAHN traffic
• SAHN services
• run alongside
• TCP/IP
• Conceived by
• Ronald Pose
• Carlo Kopp

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Who should be using
Potential Users of a SAHN Cell (1)

• Home office and professionals requiring broadband
  connection to organisations systems
• Internetworking of businesses with their offices
  spread through a suburb, campus buildings etc
• People living around their campus can access the
  universitys network via SAHN without expensive
  commercial Telecom services

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Users2
Potential Users of a SAHN Cell (2)

• Cooperative users can communicate and share a
  speedy Internet connection with each other via
  SAHN
• Houses linked with video clubs can download video
  streams on demand
• Groups with online gaming interests

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Standalone SAHN
A Standalone SAHN Node

• Appears to host like a cable modem
• Functionally more like a
• RF LAN repeater
• Embedded
• microprocessor
• protocol engine
• implements all SAHN protocols and manages and
  configures the system
• Each SAHN node has at least 2 wireless links
• Capable of achieveing link rate throughput

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SAHN Issue1
Design Challenges for SAHN Development

• Investigating wireless technology
• An appropriate routing solution
• A robust node authetication scheme
• Appropriate security models for various layers
• Integrating SAHN specific hardware and software
  solutions at minimum cost
• A suitable business model for exploiting the SAHN
  concept

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Design Issues2
Design Challenges for SAHN Development

• Investigating wireless technology
• An appropriate routing solution
• A robust node authetication scheme
• Appropriate security models for various layers
• Integrating SAHN specific hardware and software
  solutions at minimum cost
• A suitable business model for exploiting the SAHN
  concept

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References1
References

• R. Pose and C. Kopp. Bypassing the Home Computing
  Bottleneck The Suburban Area Network. 3rd
  Australasian Comp. Architecture Conf. (ACAC).
  February, 1998. pp.87-100.
• A. Bickerstaffe, E. Makalic and S. Garic. CS
  honours theses. Monash University.
  www.csse.monash.edu.au/rdp/SAN/. 2001
• Paul Conilione, QoS for Suburban Ad Hoc
  Networks. Honours Interim Presentation, CSSE,
  Monash University, 5th June 2003

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Index2
Topics
Overview of SAHN Routing in SAHN
(SAHNR) Simulation Results Future Work Current
Project Status Acknowledgements
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SAHN Goals
Design Challenges for SAHN Routing (1)

• Wireless medium inherently vulnerable to
• Eavesdropping
• DoS attacks
• Node masquerading
• Requires security policies implemented at all
  levels
• Wireless technologies (e.g. 802.11) do not
  feature resource
• Access control
• Management
• Requires higher level protocols

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SAHN Goals
Design Challenges for SAHN Routing (2)

• Ad-Hoc wireless networks have to
• Handle node/link failures
• Find routes on demand
• Route packets with QoS
• Requires an efficient on-demand routing solution

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Existing Routing0
Possible Routing Solutions for SAHN (1)

• Table Driven
• Maintains multiple tables for route information
• Constant overhead for routing control packets
• e.g. DSDV, WRP, GSP, FSR, HSR
• On Demand
• Finds routes on demand
• Reduced overhead of routing control packets
• e.g. AODV, DSR, AOMDV, MSR, TORA, ABR

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Existing Routing1
Possible Routing Solutions for SAHN (2)

• Hybrid
• Employes both table driven and on demand routing
  techniques
• e.g. LANMAR
• Others
• Ensures QoS routing
• Can be any of the above three types

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Existing Routing1
Possible Routing Solutions for SAHN (3)

• Dynamic source routing (DSR)
• On demand
• Emplyes source routing
• Can find multiple routes
• Network overhead increases for carrying source
  routes
• No security at network layer
• Does not consider QoS for route selection
• Does not feature load balancing

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Existing Routing1
Possible Routing Solutions for SAHN (4)

• Ad Hoc on demand distance vector routing (AODV)
• On demand
• Cannot find multiple routes to a destination
• No security at network layer
• Does not consider QoS for route selection
• No support for load balancing

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Why Hybrid Approach1
Why Customized Routing for SAHN ?

• Existing solutions do not feautrure one or more
  of the following attributes
• Multiple routes to a destination
• Resource Access Control
• QoS
• Load balancing
• Security at network layer
• Optimization for quasi-static networks

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SAHNR1
Properties of SAHN Routing Protocol (SAHNR) (1)

• Keeps up-to-date neighbour information
• Employs source routing for route discovery
• Maintains routes dynamically
• Employs features of DSR.
• e.g. gratuitous Route replies,
• salvaging data/error packets etc.

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SAHNR1
Properties of SAHN Routing Protocol (SAHNR) (2)

• Decreases network overhead
• Excludes source route in every data packet
• Avoids selfish/uncoordinated routing strategy
• Makes use of available paths having QoS
• Chooses least congested paths
• Balances load among available paths
• Features network level security by
• Node authentication
• Encryption of packet header information

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SAHNR2
Phases of SAHNR

• Neighbour Discovery and Authentication
• Periodically and on demand
• Route Discovery
• On demand
• Data Transmission
• On demand
• Route Maintenance
• Periodically and on demand

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Neighbor Discovery1
Neighbour Discovery (1)

• Performed
• When a node is powered up
• After an idle period if needed
• Main tasks are
• Node authentication
• Negotiation of security scheme for network layer
• Requires
• Hello/Hello Reply packets

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Nehbourhood Discovery2
Neighbour Discovery (2)
Node N wants to join SAHN
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Nehbourhood Discovery2
Generating 'Hello' Packet (1)
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Nehbourhood Discovery2
Generating 'Hello' Packet (2)
Node N broadcasts Hello packets and S, B, C, F,
G receive them
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Neighbor Discovery3
Processing 'Hello' Packet
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Neighbor Discovery3
Generating 'Hello Reply' Packet
Nodes S, B, C, F and G unicast Hello Reply
packet to N
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Neighbor Discovery3
Neighbour Discovery (3)
Now node N becomes a part of SAHN
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Route Discovery1
Route Discovery

• Performed if
• Route is not present in routing table
• Route has expired
• Requires
• RREQ and RREP packets
• Uses negotiated encrytion/decryption key for
  RREQ/RREP packet encrytion/decryption

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Route Discovery2
Initiating Route Discovery
S wants route to X. S broadcasts RREQ packets to
its neighbours
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Route Discovery2
Processing RREQ Packet (1)

• Intermediate Nodes e.g. B does not have a route
  to Node X
• B updates its routing table/forwarding table with
  unknown information
• Appends its address and QoS information in RAQL
• Broadcasts RREQ to its neighbours

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Route Discovery2
Processing RREQ Packet (2)
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Route Discovery3
Generating RREP Packet (1)

• Intermediate node H has routes to X
• H updates its routing/forwarding table with
  unknown information
• Appends H and QoSH with RAQL
• Appends route to X and QoS information with RAQL
• Reverses RAQL
• Forwards RREP to E from RAQL
• Same steps for X if it receives a RREQ

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Route Discovery3
Generating RREP Packet (2)
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Route Discovery4
Processing RREP packets (1)

• Intermediate Nodes receive RREP packets
• Update their routing/forwarding tables
• Update QoS values of RAQL
• Forward RREP
• Node S receives RREP packets
• Updates its routing/forwarding table
• Records routes
• Selects suitable routes with acceptible QoS to
  send data

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Route Discovery4
Processing RREP packets (2)
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Data Transmission1
Processing Initial Data packets

• First few data packets contains full RAQL
• An intermediate node
• Updates its routing/forwarding tables with
  unknown information
• Forwards data packet to the next node from RAQL

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Data Transmission2
Processing Remaining Data packets

• Remaining data packets do not contain RAQL
• An intermediate node
• Finds the next node from the forwarding table
  with ltGlobal Source, Global Destinationgt
• Updates Local Source with its own address
• Updates its routing/forwarding tables

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Route Maintenance1
Route Maintenance (1)

• Takes actions if
• A link fails
• A route error control packet is received
• Data packets are recieved for unknown
  destinations
• A neighbour/route/forward table entry is too old

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Route Maintenance2
Route Maintenance (2)

• If the route maintenace module senses a link
  failure, it
• Tries to find alternate route to destination
• Sends RERR of the broken link to its neigbours
• Deletes corresponding entries of broken links
  from its neighbour/route/forward tables

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Route Maintenance3
Route Maintenance (3)

• If a node receives a RERR packet the route
  maintenance module
• Sends RERR to its neigbours
• Deletes corresponding entries from its
• neighbour/route/forward tables

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Route Maintenance4
Route Maintenance (4)

• If a node receives a data packet for unknown
  destination, the route maintenance module
• Tries to find a route to the destination
• If it fails, it
• Sends RERR to the source of the data packet

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Reference2
References

• A. Bickerstaffe, E. Makalic and S. Garic. CS
  honours theses. Monash University.
  www.csse.monash.edu.au/rdp/SAN/. 2001
• P. Misra. Routing Protocols for Ad Hoc Mobile
  Networks. www.cis.ohio-state.edu/jain/cis788-99/a
  dhoc_routing/index.html. 02/07/2000

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Index2
Topics
Overview of SAHN Routing in SAHN
(SAHNR) Simulation Results Future Work Current
Project Status Acknowledgements
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Simulation Setup
Simulation Setup

• Node 0 sends node 11 8000 items of 1460 bytes
  each between simulated times 30 sec to 10 hr
  through FTP.
• Node 11 sends node 0 11000 items of 1400 bytes
  each between simulated times 70 sec to 10 hr
  through FTP.
• Node 12 sends node 13 9000 items of 1500 bytes
  each between simulated times 100 sec to 10 hr
  through FTP.
• Node 0 sends node 11 13000 items of 512 bytes
  each between simulated times 15 sec to 10 hr. The
  inter departure time for
• each item is 3.1 sec.
• Node 11 sends node 0 20000 items of 1024 bytes
• each between
• simulated times
• 28.8 sec to 10 hr.
• The inter departure
• time for each
• item is 1.5 sec.

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Simulation Result1
Simulation Result (1)
Comparing data reception rates at FTP server 11
at normal condition
session duration for SAHNR
session duration for DSR
session duration for AODV
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Simulation Result 2
Simulation Result (2)
Comparing data reception rates at FTP server 11
when a node periodically switches off and on
session duration for SAHNR
session duration for DSR
session duration for AODV
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Simulation Result3
Simulation Result (3)
Comparing load of CTRL packets in the network at
normal condition
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Simulation Result4
Simulation Result (4)
Comparing load of CTRL packets in the network
when a node periodically switches off and on
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Index4
Topics Covered
Overview of SAHN Routing in SAHN
(SAHNR) Simulation Results Future Work Current
Project Status Acknowledgements
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Future works
Future Work

• Integrate all QoS metrics (bandwidth reservation,
  error rate, latency) for routing
• Incorporate security schemes i.e. node
  authentication, encryption/decryption
• Define a feasible network size packet length
• Detect non-cooperative nodes
• Perform more simulations with varied network
  sizes, different topologies with presence of
  rouge nodes
• Test SAHNR in real environment

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Index5
Topics
Overview of SAHN Routing in SAHN
(SAHNR) Simulation Results Future Work Current
Project Status Acknowledgements
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Current status
Current Project Status (1)

• Eliminated the use of Hello Hello Reply cycles
  for node authentication
• Incorporated authentication scheme with route
  discovery cycle
• Performed more simulations with different network
  topology

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Current status2
Current Project Status (2)

• Three more papers in press to be published
• Routing In Suburban Ad-Hoc Networks
• The 2003 International Conference on Computer
  Science and its Applications (ICCSA03)
• A Hybrid QoS Routing Strategy for Suburban Ad-Hoc
  Networks
• The 11th IEEE International Conference on
  Networks (ICON03)
• A Router Architecture To Achieve Link Rate
  Throughput In Suburban Ad-Hoc Networks
• The Eighth Asia-Pacific Computer Systems
  Architecture Conference (ACSAC03)

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Index6
Topics
Overview of SAHN Routing in SAHN
(SAHNR) Simulation Results Future Work Current
Project Status Acknowledgements
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Acknowledgements
Acknowledgements

• Initial definition of the SAHN architecture was
  carried out by Adrian Bickerstaffe, Enes Makalic
  and Slavisa Garic in their computer science
  honours projects in 2001 at Monash University.
  They also implemented the testbed. The current
  project builds on their excellent work.
• Part of presentation was partly done with Paul
  Conilione, using exclusively the abilities given
  to him by his Chinese Buddhist Taoist Master,
  Shifu Chow Yuk Nen

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