Introduction to Wireless AdHoc Networks Routing

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Introduction to Wireless Ad-Hoc Networks Routing

• Michalis Faloutsos
• Some slides borrowed
• From Guor-Huar Lu

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Outline

• Challenges
• Design Goals Specified by MANET (for now)
• Types of Routing
• Protocols in Detail
• Conclusion

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Challenges

• Dynamic Topologies
• Bandwidth-constrained, variable capacity links
• Energy-constrained
• Limited Physical security
• Scalability

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Types of routing

• Flat Proactive Routing
• Link state Fish-Eye Routing, GSR, OLSR.
• Table driven Destination-Sequenced Distance
  Vector (DSDV), WRP)
• On-Demand or Reactive Routing
• Ad hoc On-demand Distant Vector (AODV)
• Dynamic Source Routing (DSR)
• Hybrid Schemes
• Zone Routing ZRP, SHARP (proactive near, reactive
  long distance)
• Safari (reactive near, proactive long distance)
• Geographical Routing
• Hierarchical One or many levels of hierarchy
• Routing with dynamic address
• Dynamic Address RouTing (DART)

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Proactive Protocols

• Proactive maintain routing information
  independently of need for communication
• Update messages send throughout the network
  periodically or when network topology changes.
• Low latency, suitable for real-time traffic
• Bandwidth might get wasted due to periodic
  updates
• They maintain O(N) state per node, N nodes

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On-Demand or Reactive Routing

• Reactive discover route only when you need it
• Saves energy and bandwidth during inactivity
• Can be bursty -gt congestion during high activity
• Significant delay might occur as a result of
  route discovery
• Good for light loads, collapse in large loads

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Hybrid Routing

• Proactive for neighborhood, Reactive for far away
  (Zone Routing Protocol, Haas group)
• Proactive for long distance, Reactive for
  neighborhood (Safari)
• Attempts to strike balance between the two

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Hierarchical Routing

• Nodes are organized in clusters
• Cluster head controls cluster
• Trade off
• Overhead and confusion for leader election
• Scalability intra-cluster vs intercluster
• One or Multiple levels of hierarchy

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Geographical Routing

• Nodes know their geo coordinates (GPS)
• Route to move packet closer to end point
• Protocols DREAM, GPSR, LAR
• Propagate geo info by flooding (decrease
  frequency for long distances)

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Theoretical perspective

• The capacity of a wireless
• network is
• Where N nodes, and C channel
• capacity
• Explanation N nodes in the field
• Destinations are random
• On average N0.5 hops per path
• Each node has N0.5 paths go through
• Gupta Kumar paper

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Mobility increases capacity

• Grossglausser and Tse (infocom 2001)
• Statement if nodes move they will enentually
  carry the info where you want
• Protocol
• sender send one copy to receiver or one neighbor
• Sender and relay will at some run into
  destination and send the packet
• All paths are at most two hops
• They show that the capacity of the network does
  not go to zero
• Tradeoff?

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Hierarchical routing bounds

• Cluster nodes, and route between and within
  clusters
• Location management finding where
• Routing finding how to get there
• Multiple levels log(N) levels
• Location Mgm Each nodes stores O(N) locations
• Routing overhead O(log3N)
• Dominating factor location management and not
  the routing
• Location mgmt handoff O(log2N)
• See Susec Marsic, infocom 02

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Types of routing

• Flat Proactive Routing
• Link state Fish-Eye Routing, GSR, OLSR.
• Table driven Destination-Sequenced Distance
  Vector (DSDV), WRP)
• On-Demand or Reactive Routing
• Ad hoc On-demand Distant Vector (AODV)
• Dynamic Source Routing (DSR)
• Hybrid Schemes
• Zone Routing ZRP, SHARP (proactive near, reactive
  long distance)
• Safari (reactive near, proactive long distance)
• Geographical Routing
• Hierarchical One or many levels of hierarchy
• Routing with dynamic address
• Dynamic Address RouTing (DART)

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Proactive DSDV - Destination-Sequenced Distance
Vector Algorithm

• By Perkins and Bhagvat
• Based on Bellman Ford algorithm
• Exchange of routing tables
• Routing table the way to the destination, cost
• Every node knows where everybody else is
• Thus routing table O(N)
• Each node advertises its position
• Sequence number to avoid loops
• Maintain fresh routes

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DSDV details

• Routes are broadcasted from the receiver
• Nodes announce their presence advertisements
• Each broadcast has
• Destination address originator
• No of hops
• Sequence number of broadcast
• The route with the most recent sequence is used

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Reactive Ad-Hoc On-demand Distance Vector
Routing (AODV)

• By Perkins and Royer
• Sender tries to find destination
• broadcasts a Route Request Packet (RREQ).
• Nodes maintain route cache and use destination
  sequence number for each route entry
• State is installed at nodes per destination
• Does nothing when connection between end points
  is still valid
• When route fails
• Local recovery
• Sender repeats a Route Discovery

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Route Discovery in AODV 1
Propagation of Route Request (RREQ) packet
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Route Discovery in AODV 2
Path taken by Route Reply (RREP) packet
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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

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Dynamic Source Routing (DSR)

• Two mechanisms Route Maintenance and Route
  Discovery
• Route Discovery mechanism is similar to the one
  in AODV but with source routing instead
• Nodes maintain route caches
• Entries in route caches are updated as nodes
  learn new routes.
• Packet send carries complete, ordered list of
  nodes through which packet will pass

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When Sending Packets

• Sender checks its route cache, if route exists,
  sender constructs a source route in the packets
  header
• If route expires or does not exist, sender
  initiates the Route Discovery Mechanism

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Route Discovery 1 (DSR)
Building Record Route during Route Discovery
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Route Discovery 2 (DSR)
Propagation of Route Reply with the Route Record
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Route Maintenance

• Two types of packets used Route Error Packet and
  Acknowledgement
• If transmission error is detected at data link
  layer, Route Error Packet is generated and send
  to the original sender of the packet.
• The node removes the hop is error from its route
  cache when a Route Error packet is received
• ACKs are used to verify the correction of the
  route links.

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The Zone Routing Protocol (ZRP)

• Hybrid Scheme
• Proactively maintains routes within a local
  region (routing zone)
• Also a globally reactive route query/reply
  mechanism available
• Consists of 3 separate protocols
• Protocols patented by Cornell University!

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Intrazone Routing Protocol

• Intrazone Routing Protocol (IARP) used to
  proactively maintain routes in the zone.
• Each node maintains its own routing zone
• Neighbors are discovered by either MAC protocols
  or Neighbor Discovery Protocol (NDP)
• When global search is needed, route queries are
  guided by IARP via bordercasting

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Interzone Routing Protocol

• Adapts existing reactive routing protocols
• Route Query packet uniquely identified by
  sources address and request number.
• Query relayed to a subset of neighbors by the
  bordercast algorithm

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Comparisons 1

• Things in common
• IP based operation
• Distributed operation
• Loop-free routing
• Very little or no support for sleep period
  operation and security

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Comparisons 2
DSDV
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Conclusion

• On-demand routing protocols (AODV and DSR) are
  gaining momentum.
• More analysis and features are needed
  (Performance comparison between protocols, QoS
  extension and analysis, multicast, security
  issues etc)
• Good paper (though old)
• A review of current routing protocols for ad-hoc
  mobile wireless networks, E. Royer, C.K. Toh

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Performance?

• End-to-end data throughput and delay
• Route acquisition time
• Percentage of out-of-order delivery
• Efficiency
• Average number of data bits transmitted/data bits
  delivered
• Average number of control bits transmitted/data
  bits delivered
• Average number of control and data packets
  transmitted/data packet delivered

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Parameters

• Network Size
• Connectivity (average degree of a node)
• Topology rate of change
• Link capacity (bps)
• Fraction of unidirectional links
• Traffic patterns
• Mobility
• Fraction/frequency of sleeping nodes

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References

• Mobile Ad hoc Networking (MANET) Routing
  Protocol Performance Issues and Evalution
  Considerations (RFC 2501)
• P. Misra., Routing Protocols for Ad Hoc Mobile
  Wireless Networks, http//www.cis.ohio-state.edu/
  jain/cis788-99/adhoc_routing/
• The Zone Routing Protocol (ZRP) for Ad Hoc
  Networks ltdraft-ietf-manet-zone-zrp-04.txtgt
• Fisheye State Routing Protocol (FSR) for Ad Hoc
  Networks ltdraft-ietf-manet-fsr-03.txtgt
• Ad hoc On-demand Distance Vector (AODV) Routing
  ltdraft-ietf-manet-aodv-11.txtgt
• The Dynamic Source Routing Protocol for Mobile Ad
  Hoc Networks (DSR) ltdraft-ietf-manet-dsr-07.txtgt

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Fisheye State Routing (FSR)

• Node stores the Link State for every destination
  in the network
• Node periodically broadcast update messages to
  its neighbors
• Updates correspond to closer nodes propagate more
  frequently

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Multi-Level Scope (FSR)

• Central node (red dot) has the most accurate
  information about nodes in white area and so on.
• Parameters Scope level/radius size

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ZPR architecture
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Design Goals

• Peer-to-peer mobile routing capability in mobile,
  wireless domain.
• Intra-domain unicast routing protocol
• Effective operation over a wide range of mobile
  networking scenarios and environments
• Supports traditional, connectionless IP services
• Efficiently manages topologies changes and
  traffic demands

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Desired properties

• Distributed operation
• Loop freedom
• Demand-based operation
• Proactive operation
• Security
• Sleep period operation
• Unidirectional link support