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Introduction to Wireless Ad-Hoc Networks Routing

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Title: Introduction to Wireless Ad-Hoc Networks Routing


1
Introduction to Wireless Ad-Hoc Networks Routing
  • Michalis Faloutsos
  • Some slides borrowed
  • From Guor-Huar Lu

2
Outline
  • Challenges
  • Design Goals Specified by MANET (for now)
  • Types of Routing
  • Protocols in Detail
  • Conclusion

3
Challenges
  • Dynamic Topologies
  • Bandwidth-constrained, variable capacity links
  • Energy-constrained
  • Limited Physical security
  • Scalability

4
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)

5
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

6
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

7
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

8
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

9
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)

10
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

11
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?

12
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

13
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14
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)

15
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

16
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

17
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

18
Route Discovery in AODV 1
Propagation of Route Request (RREQ) packet
19
Route Discovery in AODV 2
Path taken by Route Reply (RREP) packet
20
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

21
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

22
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

23
Route Discovery 1 (DSR)
Building Record Route during Route Discovery
24
Route Discovery 2 (DSR)
Propagation of Route Reply with the Route Record
25
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.

26
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!

27
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

28
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

29
Comparisons 1
  • Things in common
  • IP based operation
  • Distributed operation
  • Loop-free routing
  • Very little or no support for sleep period
    operation and security

30
Comparisons 2
DSDV
FSR AODV DSR ZPR
Source Routing No No Yes No
Periodic message Yes No No Yes (Locally)
Functioning Proactively Yes No No Yes (Locally)
Functioning Reactively No Yes Yes Yes (Globally)
31
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

32
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33
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

34
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

35
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

36
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

37
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

38
ZPR architecture
39
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

40
Desired properties
  • Distributed operation
  • Loop freedom
  • Demand-based operation
  • Proactive operation
  • Security
  • Sleep period operation
  • Unidirectional link support
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