Routing in Mobile AdHoc NetworksMANET

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Routing in Mobile Ad-Hoc Networks(MANET)

• Jianping Zou
• El938 Presentation
• on April 22, 2002

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What I will cover today

• Introduction to MANAT
• MANET Routing Protocols
• Proactive /Reactive/Hybrid Protocols
• Single-scope/Multi-scope/ Geographically Routing
  Protocols
• Temporally-Ordered Routing Algorithm(TORA)
• Performance Comparisons between TORA and ILS
  (Ideal Link State Routing Protocol)
• References

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Mobile Ad-Hoc Network

• No pre-existing fixed infrastructure
• Collection of mobile nodes form their dynamic
  routes
• MANET is a peer-to-peer network. There is no
  centralized administration
• Each mobile node(Host) is an independent router

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Challenges in Routing of MANET

• Lack of centralized entities
• ----Require distributed algorithms
  for routing
• Rapid node movement
• ----Results in frequent and
  unpredictable network topology
  change
• Limited bandwidth availability
  ----Require low-overhead algorithms for routing
• The vulnerability of radio communications to
  propagation impairments.
• Power limitationmulti-hop relay is needed.

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Features for the MANET

• Robust routing and mobility management algorithms
  
• Adaptive algorithms and protocols
• Low-overhead algorithms and protocols
• Multiple (distinct) routes between a source and a
  destination
• Robust network architecture

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MANET Protocols

• Proactive Protocols- Table driven (DSDV, WRP)
• Continuously update routes info.
• Large network capacity to keep info. up to date
• Most routing info. may never be used!

• Reactive Protocols-On demand (AODV, DSR, TORA)
• Create and discovery route when needed
• Considerable delay associated with route
  discovery due to network-wide flooding

Hybrid protocols (ZRP)
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MANET Protocols (cont.)
Ad Hoc On-Demand Distance Vector outing(AODV) 1
Dynamic Source Routing(DSR) 2
Single-Scope Routing Protocols
Temporally Ordered Routing Algorithm(TORA) 3
Destination-Sequenced Distance-Vector
Routing(DSDV) 4
Wireless Routing Protocol(WRP) 5
Zone Routing Protocol(ZRP) 6
Flat Routing Protocols
Optimized Link State Routing(OLSR) 7
Multi-Scope Routing Protocols
Fisheye State Routing(FSR) 8
Core-Extraction Distributed Ad hoc Routing(CEDAR)
Hierarchical Routing Protocols
Zone-based Hierarchical Link State(ZHLS)
Landmark Ad hoc Routing(LANMAR)
Geographically-routed Protocols
Location-Aided Routing(LAR)
Distance Routing Effect Algorithm for
Mobility(DREAM)
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TORA Attributes

• On demand, source initiated routing
• Distributed in that nodes only maintain one
  hop knowledge
• Provides multiple routes to alleviate
  congestion
• Creates loop free routes
• Handles partitions by erasing invalid routes

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Conceptual Overview of TORA
Illustration of the directed acyclic graph formed
by the relative heights of the routers.
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System Assumptions Notations

• Network modeled as a graph G (N L)
• Each node has a unique identifier (ID)
• Communication links are bi-directional and
  categorized as
• (1) undirected
• (2) directed from node i to node j i is
  upstream of j and j is downstream of
  i
• Each node i is aware of its neighbors set Ni

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An Example
(-,-,-,-,B)
(-,-,-,-,A)
(-,-,-,-,E)
(-,-,-,-,D)
(-,-,-,-,C)
DEST
(0,0,0,0,F)
(-,-,-,-,G)
(-,-,-,-,H)
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Node Height in TORA

• The height metric is an ordered quintuple (?,
  oid, r, ?, i) with the following values
• ? the logical time of a link failure, defining
  a new reference level
• oid the unique ID of the router that defined the
  reference level.
• r a reflection indicator bit
• ? a propagation ordering parameter
• i the unique ID of the router
• The first three elements collectively represent
  the reference level.

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Algorithm Overview

• Route Creation Creating routes consists of
  establishing a sequence of directed links from
  the source to the destination. This is done by
  forming a destination oriented DAG the
  destination node is the sink of the graph.
• Route Maintenance Reaction to topology changes
  in order to reestablish routes within a finite
  time.
• Route Erasure When a partition is detected in
  the network, all invalid routes must be removed
  from the network. This is done by making directed
  routes undirected.

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Route Creation

• QRY packet contains the destination-ID (did) for
  which the algorithm is running.
• UPD packet contains the did and the height of
  the node i that is broadcasting the packet Hi
• Each node maintains
• Route-required flag RRi initially unset
• Time the last UPD packet was broadcast
• Time at which each link (i j) ? L for j ? Ni
  came up
• ( When a node i with no directed links and an
  un-set RRi requires a route, it broadcasts a QRY
  packet and sets RRi. )

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• When a node i receives a QRY message, it will
• if node i has no downstream links and RRi is
  unset, it rebroadcasts the QRY message and sets
  RRi.
• if node i has no downstream links and RRi is set,
  it discards the QRY packet
• if node i has at least one downstream link and
  its height is NULL, it sets its height to Hi
  minHj j ? Ni 0 0 0 1 0 and broadcasts
  an UPD packet
• if node i has at least one downstream link and
  its height is non-NULL, and if a UPD packet has
  been broadcast since the link over which the QRY
  packet was received became active, it discards
  the QRY packet. Otherwise it broadcasts an UPD
  packet.
• Also, if RRi is set when a link becomes
  active, it broadcasts a QRY packet

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Receipt of an UPD packet

• Node i receives an UPD packet from a neighbor j,
  i updates H Ni,j to reflect the height of node j
• There are now two options
• if RRi is set (implying the height of node i is
  NULL), node i sets Hi minHj j ?Ni 0 0
  0 1 0, updates the links in LSi, unsets Rri,
  and broadcasts a UPD packet with the new info.
• if RRi is unset, node i updates the links in LSi
  (possible to lose all downstream links)

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Example1-Route Creation
(-,-,-,-,B)
(-,-,-,-,A)
(-,-,-,-,E)
QRY
(-,-,-,-,D)
(-,-,-,-,C)
DEST
Circle indicates RRi is true
(0,0,0,0,F)
(-,-,-,-,G)
(-,-,-,-,H)
Figure 1 Node C requires a route to node F. It
therefore broadcasts a QRY packet.
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(-,-,-,-,B)
(-,-,-,-,A)
QRY
(-,-,-,-,E)
(-,-,-,-,D)
(-,-,-,-,C)
DEST
(0,0,0,0,F)
QRY
(-,-,-,-,G)
(-,-,-,-,H)
Figure 2 Node A and Node G propagate the QRY
packet.
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(-,-,-,-,B)
(-,-,-,-,A)
QRY
(-,-,-,-,E)
(-,-,-,-,D)
(-,-,-,-,C)
QRY
DEST
UPD
(0,0,0,0,F)
(-,-,-,-,G)
(0,0,0,1,H)
Figure 3 Nodes B and D propagate the QRY packet.
Node H generates a UPD packet.
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(-,-,-,-,B)
(-,-,-,-,A)
(0,0,0,1,E)
UPD
(0,0,0,2,D)
(-,-,-,-,C)
UPD
DEST
UPD
(0,0,0,0,F)
(0,0,0,2,G)
(0,0,0,1,H)
Figure 4 Nodes D and G propagate the UPD packet
while node E generates a UPD packet.
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(0,0,0,2,B)
(0,0,0,3,A)
UPD
UPD
(0,0,0,1,E)
UPD
(0,0,0,2,D)
(0,0,0,3,C)
DEST
(0,0,0,0,F)
(0,0,0,2,G)
(0,0,0,1,H)
Figure 5 Nodes A, B, and C propagate the UPD
packet.
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(0,0,0,2,B)
(0,0,0,3,A)
(0,0,0,1,E)
(0,0,0,2,D)
(0,0,0,3,C)
(0,0,0,2,G)
(0,0,0,1,H)
Figure 6 Route creation has completed.
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Route Maintenance
(0,0,0,2,B)
(0,0,0,3,A)
(0,0,0,1,E)
(0,0,0,3,C)
(0,0,0,2,D)
DEST
(0,0,0,2,G)
(0,0,0,0,F)
(0,0,0,1,H)
No route maintenance is necessary because all
nodes have at least one outgoing link (except for
DEST) which means each node has a route to DEST.
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Route MaintenanceCase 1
(0,0,0,2,B)
(0,0,0,3,A)
(0,0,0,1,E)
(1,D,0,0,D)
(0,0,0,3,C)
UPD
DEST
(0,0,0,0,F)
(0,0,0,2,G)
(0,0,0,1,H)
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General Reversal Algorithms
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Case 2
(1,D,0,-1,B)
(0,0,0,3,A)
UPD
UPD
(0,0,0,1,E)
(1,D,0,0,D)
(0,0,0,3,C)
DEST
(0,0,0,2,G)
(0,0,0,1,H)
(0,0,0,0,F)
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Case 3
(0,0,0,2,B)
(1,0,0,-2,B)
(0,0,0,3,A)
(1,0,0,-3,A)
(0,0,0,1,E)
(0,0,0,3,C)
(1,0,1,0,C)
(0,0,0,2,D)
(1,0,0,-1,D)
DEST
(0,0,0,2,G)
(1,0,0,-1,G)
(0,0,0,0,F)
(0,0,0,1,H)
(1,0,0,0,H)
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Case 4
(0,0,0,1,E)
(1,0,0,-2,B)
(1,0,1, -2,B)
(1,0,0,-3,A)
(1,0,1, -1,A)
(0,0,0,3,C)
(1,0,1,0,C)
DEST
(1,0,0,-1,D)
(1,0,1, -3,D)
(0,0,0,0,F)
CLR
(1,0,0,-1,G)
(1,0,1,-1,G)
(1,0,0,0,H)
(- ,- ,-, -, H)
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Erasing Routing

• Erasing routing is performed when network
  partition is detected.
• When network partition is detected, clear
  packet (CLR) is flooding throughout the network
  to erase invalid routes.
• When a node i receives a CLR, it sets its height
  and the height entry for each neighbor to NULL

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Erasing Routing Example
(1,0,0,-2,B)
(1,0,1, -2,B)
(- ,- ,-, -, B)
(1,0,0,-3,A)
(1,0,1, -1,A)
(- ,- ,-, -, A)
CLR
(0,0,0,1,E)
CLR
CLR
(0,0,0,3,C)
(1,0,1,0,C)
(- ,- ,-, -, C)
(1,0,0,-1,D)
(1,0,1, -3,D)
(- ,- ,-, -, D)
CLR
DEST
CLR
(1,0,0,-1,G)
(1,0,1,-1,G)
(- ,- ,-, -, G)
CLR
(- ,- ,-, -, H)
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Performance Analysis

• Compare the TORA with Ideal Link-State (ILS)
  routing and pure flooding.
• Comparison with ILS is due to its simplicity and
  familiarity
• Comparison with flooding due to when topology
  change fast all other routing protocol will use
  flooding.
• Three network characteristics were varied to
  study performance
• Network size
• Rate of topological change
• Network connectivity

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Simulation Model
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Performance Analysis (contd.)

• Following parameters are measured.
• Bandwidth utilization efficiency
• Number of data bits transmitted per message bit
  delivered
• Number of control overhead bits transmitted per
  message bit delivered.
• Total number of bits transmitted per message bit
  delivered.
• Mean message delay

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Performance Analysis (contd.)

• The following results are based on 49 node
  network.
• The traffic loads is 1.5packets/node/minutes.
• The link mean time to failure is varied.

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Performance Analysis (contd.)
36
Performance Analysis (contd.)
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Conclusion

• For a given available bandwidth as the rate of
  network topological change(or the size of
  network) increases, the performance of TORA
  eventually exceeds that of ILS (ideal link state
  protocol).