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Routing in Manet
 

Routing in Manet

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Routing in Manet

Routing in Manet

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Routing in Manet Routing in Manet Presentation Transcript

  • Routing in MANET
  • Agenda
    • Ad-Hoc Introduction
    • What MANET it is
    • Proactive protocol
      • DSDV
    • Reactive protocol
      • AODV
      • DSR
    • Hybrid Protocol
      • ZRP
    • Conclusion
  • Ad-Hoc Introduction
    • Broadband Wireless Access
      • Infrastructure Network – Base Station/ Access Point
      • Ad-Hoc Network – Mobile device(ex: MANET )
    Infrastr-ucture Ad-Hoc Infrastructure Ad-Hoc Need connect to Ethernet Not need Base station single -hop multi -hop Central Control Distributed routing Cost high Cost low Construct slow Construct fast Time synchronization easy Time synchronization tough
  • Ad-Hoc Development
  • MANET(Mobile Ad-Hoc Network) Features
  • MANET Application
  • MANET Issue
  • MANET Routing Protocol(1/2)
  • MANET Routing Protocol(2/2)
    • Table-driven/Proactive
      • more similar to conventional routing
      • Update table information with a period
    • On-demand-driven/Reactive
      • only obtain route information when needed
    • Hybrid
      • both proactive and reactive in nature
  • Destination-Sequenced Distance Vector Protocol(DSDV)
    • Highly Dynamic Destination-Sequenced Distance Vector Routing for Mobile Computer
    • Charles E. Perkins,
    • IBM, T.J. Waston Research Center Hawthrone, NY 10562
    • Pravin Bhagwat,
    • Computer Science Department University of Maryland College Park, MD 20742
    • Speaker :許景涵
  • Destination-Sequenced Distance Vector Protocol
    • By using routing tables stored at each station of the network.
      • Each node maintains routing information for all known destinations
    • Advertise to each neighbor own routing information
    • To maintain the consistency of routing tables in a dynamically varying topology
      • Periodically transmits updates
      • Immediately transmits updates as needed
  • Distance-Vector MH3 MH2 MH4 MH6 MH5 MH8 MH7 MH1
  • The Forwarding Routing Table
    • All available destinations
    • Next hop for each destination
    • Number of hops to each available destination
    • A sequence number for each route table entry, originated by the destination station
    • Example : MH4
    Destination Next Hop Metric Seq. No Install Time Stable Data MH1 MH2 2 S406_MH1 T001MH4 Ptr1_MH1 MH2 MH2 1 S128_MH2 T001MH4 Ptr1_MH2 MH3 MH2 2 S564_MH3 T001MH4 Ptr1_MH3 MH4 MH4 0 S710_MH4 T001MH4 Ptr1_MH4 Etc.
  • Route Selection
    • Update information is compared to own routing table
      • Select route with higher destination sequence number – to ensure using newest information from destination
      • Select the route with better metric when sequence numbers are equal.
    • The Receiver adds an increment to the metric.
  • Rules to set sequence number Information
    • On each advertisement increase own destination sequence number
      • use only even numbers
    • If a node is no more reachable (timeout)
      • increase sequence number of this node by 1
      • set metric =  .
    Destination Next Hop Metric Seq. No Install Time Stable Data MH1 MH1 1 S406_MH1 T001MH2 Ptr1_MH1 MH2 MH2 0 S128_MH2 T001MH2 Ptr1_MH2 MH3 MH3  S561_MH3 T001MH2 Ptr1_MH3 MH4 MH4 1 S710_MH4 T001MH2 Ptr1_MH4 Etc.
  • Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5
  • Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5 MH 4 Forwarding table: Destination Next Hop Metric Seq. No MH 1 MH 2 2 S406_MH 4 MH 2 MH 2 1 S128_MH 1 MH 3 MH 2 2 S564_MH 2 MH 4 MH 4 0 S710_MH 3 MH 5 MH 6 2 S392_MH 5 MH 6 MH 6 1 S076_MH 6 MH 7 MH 6 2 S128_MH 7 MH 8 MH 6 3 S050_MH 8
  • Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5 MH 1
    • Update triggered by MH 1 , broadcasted to MH 7 and MH 8
    • On detection of broken link: Immediate incremental update triggered by MH 2 with odd sequence number and infinite metric
    • Updates are propagated through the network
  • Example of DSDV in operation MH 3 MH 6 MH 2 MH 7 MH 4 MH 8 MH 5 MH 1 MH 4 advertised table (updated): Destination Next Hop Metric Seq. No MH 1 MH 6 3 S516_MH 4 MH 2 MH 2 1 S238_MH 1 MH 3 MH 2 2 S674_MH 2 MH 4 MH 4 0 S820_MH 3 MH 5 MH 6 2 S502_MH 5 MH 6 MH 6 1 S186_MH 6 MH 7 MH 6 2 S238_MH 7 MH 8 MH 6 3 S160_MH 8
  • Adjustment in carried information
    • Reduce the amount of information carried in these packets
      • Full dump will carry all the available routing information.
      • Incremental packets: all information that has changed since the last full dump
    • Full dump if incremental dump exceeds one NPDU (network protocol data unit)
    • Full dumps can be transmitted relatively infrequently , when no movement of Mobile Hosts is occurring.
  • Receiving Fluctuating Routes
    • What might happen:
    • MH 9 broadcasts update information to MH Collections I and II
    • MH 2 transmits new routing information to MH 4
    • MH 4 : new sequence number  routing table update  broadcast update
    • MH 6 transmits new routing information to MH 4 , same sequence number, better metric
    • MH 4 : same seq.no., better metric  update routing table  broadcast update
  • Damping Fluctuation
    • Causes for Fluctuation:
      • Many hosts with irregular updates
      • Different propagation speed
      • Different transmission intervals
      • Broadcasts are asynchronous events
    • Solution: Keep a route settling time table in each node with a time to wait for a route with a better metric before advertising the update message.
  • Route Settling Time Table
    • Decide how long to wait before advertising.
    • Calculated by maintaining a running weighted average over the most recent updates of the routes for each destination.
    • The settling time data is store in a table with following fields
      • Destination address
      • Last setting time
      • Average settling time-use for this determination
  • DSDV Disadvantages and Improvement
    • Disadvantages
      • Periodically updates : No sleeping nodes
      • Bi-directional links required
      • Overhead: most routing information never used
      • Scalability is a major problem
    • Many improved protocols based on DSDV have been developed
      • Example: AODV: Ad-hoc On-Demand Distance Vector Routing
  • Unidirectional and Bi-directional links A B C D
  • DSDV Disadvantages and Improvement
    • Disadvantages
      • Periodically updates : No sleeping nodes
      • Bi-directional links required
      • Overhead: most routing information never used
      • Scalability is a major problem
    • Many improved protocols based on DSDV have been developed
      • Example: AODV: Ad-hoc On-Demand Distance Vector Routing
  • Ad Hoc On-Demand Distance Vector Routing Protocol (AODV)
    • Speaker :方祥軒
    Ad-hoc On-Demand Distance Vector Routing ECE697A Advanced Computer Networks Presented by Qifeng Lu Scalable AODV with Efficient Flooding based on On-Demand (Passive) Clustering Yunjung Yi and Mario Gerla University of California, Los Angeles
  • Outline
    • Introduction
    • AODV Features
    • AODV Algorithm
  • Introduction
    • An improved algorithm of DSDV
    • A Source Initiated ( reactive ) routing protocol
    • Main goals:
      • Quick adaptation under dynamic link conditions
      • Lower transmission latency
      • Low network utilization ( less broadcast )
      • Loop-free property (How: using destination sequence #)
  • AODV Features V.S. DSDV Routes are created only when required Each node doesn’t maintain all routes to other nodes (only active routes) Use of sequence numbers at each destination to maintain freshness of routing information( solve loop problem ) Reduces periodic broadcast Paths generated are loop-free Uses symmetric links (if a link is not symmetric it is not up) Works both on wired media and wireless media
  • AODV Algorithm
    • Path Discovery
      • Reverse Path Setup
      • Forward Path Setup
    • Route Table Management
    • Path Maintenance
  • Path Discovery
    • Route Discovery
      • Route Requests( RREQ)
      • Route Replies (RREPs)
    • Route Maintenance
      • Route Errors (RERRs)
  • Route Discovery(1/2) Unique Unique RREQ freshness Reverse freshness RREQ RREQ source_addr source_sequence_# broadcast_id dest_addr dest_Sequence_# hop_cnt
  • Route Discovery(2/2)
    • Route Reply (RREP)
    RREP RREP source_addr hop_cnt dest_addr source_sequence_# lifetime (expiration time for reverse path route entry)
  • Reverse Path Setup
    • Initiated when no route to reach destination node
    S D RREP (Route Reply) RREQ (Route Request) Drop ClusterHead Gateway Ordinary Node
  • Forward Path Setup
    • RREQ arrives at a node that has current route to the destination ( larger/same sequence number )
    sequence number = 99 sequence number = 101 REEQ sequence number = 100 A C B D T^T Send RREQ =V= Send RREP Unicast
  • Route Table Management
    • Route request expiration time: to purge reverse path routing entries from nodes are not on the path from source to destination
    • Route caching timeout: when the route is considered to be invalid
    A B C D RERR
  • AODV with Efficient Flooding
    • Clustering Scheme
      • Cluster heads and gateways are dominant nodes
    • Advantage
      • Reduce AODV routing overhead
      • Improves AODV scalability
    S D ClusterHead Gateway Ordinary Node
  • Dynamic Source Routing (DSR)
    • Routing in Ad-Hoc Networks And the DSR Protocol
    • Computer Network Dr. Jorge A. Cobb
    • Upgrading Performance of DSR Routing Protocol in Mobile Ad Hoc Networks
    • Mehdi Alilou , Mehdi Dehghan.t
    • TPBDSR: A New DSR-based Energy Saving Routing in MANET
    • XU Li WU Zi-wen & ZHENG Bao-yu
    • Speaker :呂璇
  • Dynamic Source Routing (DSR)
    • On demand : No periodic router advertisements
    • Source routing : to send a packet to another host, the sender constructs a source route in the packet’s header
    • Caching : each mobile host participating in the ad hoc network maintains a route cache in which it caches source routes
  • Two Main Components
    • Route Discovery
      • the mechanism by which a sending node S obtains a route to destination D
    • Route Maintenance
      • the mechanism by which a sending node S detects that the network topology has changed and its route to D is no longer valid
  • Route Discovery(1/13)
    • When two nodes which are not in wireless rang of each other, want to communicated with each other.
    • process.
  • Route Discovery(2/13) Represents a node that has received RREQ for D from S B A S E F H J D C G I K Z Y M N L
  • Route Discovery(3/13)
    • When two nodes which are not in wireless rang of each other, want to communicated with each other.
    • If the source node has the related route to destination in its cache memory
    • -> Insert the route in data packet headers and the packets will be sent from that specified route .
    • If it doest have the related route to destination
    • -> Begin the route discovery process.
  • Route Discovery(4/13)
      • Step 1 : Source( S ) broadcasts RREQ message for specified destination( D ).
    • R oute Req uest packet (RREQ)
    • Destination Address
    • Source Address
    • Request ID
    • Route Record
  • Route Discovery(5/13) Represents transmission of RREQ Broadcast [S] [X,Y] Represents route record stored in RREQ B A S E F H J D C G I K Z Y M N L
  • Route Discovery(6/13)
      • Step 2 : When intermediate node receive RREQ message.
      • Adds itself to path in message
      • Forwards (broadcasts) message toward D until……
      • A node that has a route to D is found ->
      • Early Route-Replies.
  • Route Discovery(7/13) [S,E] [S,C] [S,B] B A S E F H J D C G I K Z Y M N L
  • Route Discovery(8/13)
      • Step 2 : When intermediate node receive RREQ message.
      • Adds itself to path in message
      • Forwards (broadcasts) message toward D until……
      • A node that has a route to D is found ->
      • Early Route-Replies.
      • A node has already received the same RREQ message -> Discard the packet.
    Source Address Request ID
  • Route Discovery(9/13)
    • C receives RREQ from G and H , but does not forward
    • it again, because C has already forwarded RREQ once
    [S,C,G] [S,E,F] [S,B,A] [S,B,H] B A S E F H J D C G I K Z Y M N L
  • Route Discovery(10/13) J and K both broadcast RREQ to D [S,C,G,K] [S,E,F,J] [S,B,H,I] [S,E,F,J,D] [S,C,G,K,D] B A S E F H J D C G I K Z Y M N L
  • Route Discovery(11/13) D does not forward RREQ, because D is the intended target [S,E,F,J,M] B A S E F H J D C G I K Z Y M N L
  • Route Discovery(12/13)
      • Step 3 : When D receive RREQ message, it copies route into a RREP packet and sends it back to S.
      • R oute Rep ly packet (RREP)
      • If MAC protocol is bidirectiona l , use reverse path as data.
      • With unidirectional links , Destination may need to discover route to source to deliver Route Reply
      • If a route exists in its cache, use it
      • O.W. piggyback Route Reply onto new Route Request
  • Route Discovery(13/13) RREP [S,E,F,J,D] Represents RREP control message B A S E F H J D C G I K Z Y M N L
  • Route Maintenance(1/6)
    • Used when link breakage occurs.
    • Step 1 : Intermediate nodes using Acknowledge to detect link status/breakage.
      • link-layer ACKs (MACAW)
      • passive ACKs
      • DSR ACK request
  • Route Maintenance(2/6) B A S E F H J D C G I K Z Y M N L
  • Route Maintenance(3/6)
    • Step 2 : The intermediate node sent RERR message to S when break detected.
    • R oute Err or (RERR)
    • Bidirectional -> Reverse path
    • Unidirectional -> Cache or Piggyback
  • Route Maintenance(4/6) Represents RERR message [S,E,F] B A S E F H J D C G I K Z Y M N L
  • Route Maintenance(5/6)
    • Step 3 : Source deletes rout e .
    • Step 4 : Source try another path if one cached, or issues new RREQ (new route discovery).
  • Route Maintenance(6/6) [S,E,F,J,D] [S,C,G,K,D] B A S E F H J D C G I K Z Y M N L
  • DSR vs. AODV AODV DSR Path Information Limited information More detail Times of Route Discovery Many Few Traffic when RREP Low High Live time of route path New We don’t know Delete invalid path when RRER Delete all Only delete some node
  • Hybrid Protocol
    • Zone Routing Protocol (ZRP) combines
      • Proactive protocol/ Table-Driven : Intra-Zone Routing
      • Reactive protocol/ On-Demand : Inter-Zone Routing
    Routing Zone Inter-Zone Routing Intra-Zone Routing On-Demand Table-Driven
  • Conclusion(1/2) Routing class Proactive Reactive Hybrid Routing structure Both Mostly flat Mostly hierarchical Availability of route Always available Determined when needed Depend on the location of the destination Control traffic volume High medium low Periodic updates Yes No Usually used inside each zone , or between gateways Handling effects of mobility Usually updates occur at fixed intervals. AODV,DSR uses local route discovery Usually more than one path maybe available. Single point of failures are reduced by working as a group
  • Conclusion(2/2) Routing class Proactive Reactive Hybrid Storage requirements High Depends on the number of routes kept or required. Usually lower than proactive protocols Usually depends on the size of each cluster or zone may become as large as proactive protocols if clusters are big Delay level Small routes are predetermined Higher than proactive For local destinations small. Inter-zone maybe as large as reactive protocols Scalability level Usually up to 100 nodes. Source routing protocols up to few hundred nodes. Designed for up to 1000 or more nodes
  • References
    • A review of routing protocols for mobile ad hoc networks
    • Mehran Abolhasan , Tadeusz Wysocki , Eryk Dutkiewicz
    • 以路徑為基礎的 MANET 網路群播路由協定之研究
    • 研究生: 蘇平嘉 指導教授: 陳彥文
    • 無線 Ad Hoc 行動隨意網路架構之技術發展評析
    •  惠汝生
  • Q&A
    • Thanks for your attention!