1) The document describes the Ad Hoc On-Demand Distance Vector (AODV) routing protocol. AODV is a reactive protocol that discovers routes on-demand using a route discovery process.
2) When a node needs to send a packet to an unknown destination, it broadcasts a route request (RREQ) to its neighbors. Neighbors set up reverse paths and rebroadcast the RREQ until it reaches the destination node.
3) The destination or intermediate nodes with a route can send a unicast route reply (RREP) back to the source node using the reverse path. This sets up a forward path from source to destination for data packets.
The document discusses several routing protocols for mobile ad hoc networks:
- DSR allows nodes to cache and share routing information for more efficient routing but has larger packet headers due to source routing. AODV uses only next hop information, keeping routing tables smaller.
- Both protocols use route discovery and maintenance, but AODV proactively refreshes routes while DSR reacts to failures. AODV also uses sequence numbers to prevent loops and choose fresher routes.
- Overall, DSR is better for networks where routes change infrequently while AODV scales better and maintains only active routes, at the cost of higher routing overhead during route discovery. Security remains a challenge for both protocols.
Routing protocols in wireless sensor networks face several unique challenges compared to other wireless networks. The document discusses these challenges and provides an overview of common routing protocol approaches in WSNs, including flat routing protocols like SPIN and Directed Diffusion, hierarchical routing protocols like LEACH, and location-based routing protocols. It also covers routing design issues specific to WSNs such as energy efficiency, data delivery models, fault tolerance, and quality of service.
This document provides a literature review of research papers on detecting and preventing blackhole attacks in the AODV routing protocol for mobile ad hoc networks (MANETs). It summarizes 9 papers that propose various techniques like using sequence numbers, watchdog mechanisms, and route confirmation messages to identify malicious nodes and increase security. The document outlines the key ideas, results, and potential future work from each paper to improve performance and security against blackhole attacks in AODV routing.
Proactive routing protocol
Each node maintain a routing table.
Sequence number is used to update the topology information
Update can be done based on event driven or periodic
Observations
May be energy expensive due to high mobility of the nodes
Delay can be minimized, as path to destination is already known to all nodes.
LAR utilizes location information to improve routing efficiency by reducing control overhead. It uses GPS to obtain geographical information. There are two zones in LAR - the ExpectedZone where the destination is expected to be, and the RequestZone which is the area where routing packets can propagate. PAR aims to minimize energy consumption per packet by calculating the sum of energy required at each hop. It also aims for maximum network connectivity and uniform distribution of power consumption across all nodes.
This document provides an overview of routing protocols in ad hoc networks. It begins with an abstract describing the objectives of surveying and comparing different classes of ad hoc routing protocols. The document then outlines the topics to be covered, including the characteristics, applications, and types of ad hoc routing protocols. Several representative routing protocols are described in detail, including table-driven, hybrid, source-initiated, location-aware, multipath, hierarchical, multicast, and power-aware protocols. The document concludes by discussing future work related to improving reusability and security of ad hoc routing protocols.
The document discusses on-demand driven reactive routing protocols. It provides an overview of table-driven vs on-demand routing protocols and describes two popular on-demand protocols - Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing (AODV) in detail. DSR uses source routing by adding the complete route to packet headers. AODV maintains routing tables at nodes and relies on dynamically establishing next hop information for routes.
The document discusses several routing protocols for mobile ad hoc networks:
- DSR allows nodes to cache and share routing information for more efficient routing but has larger packet headers due to source routing. AODV uses only next hop information, keeping routing tables smaller.
- Both protocols use route discovery and maintenance, but AODV proactively refreshes routes while DSR reacts to failures. AODV also uses sequence numbers to prevent loops and choose fresher routes.
- Overall, DSR is better for networks where routes change infrequently while AODV scales better and maintains only active routes, at the cost of higher routing overhead during route discovery. Security remains a challenge for both protocols.
Routing protocols in wireless sensor networks face several unique challenges compared to other wireless networks. The document discusses these challenges and provides an overview of common routing protocol approaches in WSNs, including flat routing protocols like SPIN and Directed Diffusion, hierarchical routing protocols like LEACH, and location-based routing protocols. It also covers routing design issues specific to WSNs such as energy efficiency, data delivery models, fault tolerance, and quality of service.
This document provides a literature review of research papers on detecting and preventing blackhole attacks in the AODV routing protocol for mobile ad hoc networks (MANETs). It summarizes 9 papers that propose various techniques like using sequence numbers, watchdog mechanisms, and route confirmation messages to identify malicious nodes and increase security. The document outlines the key ideas, results, and potential future work from each paper to improve performance and security against blackhole attacks in AODV routing.
Proactive routing protocol
Each node maintain a routing table.
Sequence number is used to update the topology information
Update can be done based on event driven or periodic
Observations
May be energy expensive due to high mobility of the nodes
Delay can be minimized, as path to destination is already known to all nodes.
LAR utilizes location information to improve routing efficiency by reducing control overhead. It uses GPS to obtain geographical information. There are two zones in LAR - the ExpectedZone where the destination is expected to be, and the RequestZone which is the area where routing packets can propagate. PAR aims to minimize energy consumption per packet by calculating the sum of energy required at each hop. It also aims for maximum network connectivity and uniform distribution of power consumption across all nodes.
This document provides an overview of routing protocols in ad hoc networks. It begins with an abstract describing the objectives of surveying and comparing different classes of ad hoc routing protocols. The document then outlines the topics to be covered, including the characteristics, applications, and types of ad hoc routing protocols. Several representative routing protocols are described in detail, including table-driven, hybrid, source-initiated, location-aware, multipath, hierarchical, multicast, and power-aware protocols. The document concludes by discussing future work related to improving reusability and security of ad hoc routing protocols.
The document discusses on-demand driven reactive routing protocols. It provides an overview of table-driven vs on-demand routing protocols and describes two popular on-demand protocols - Dynamic Source Routing (DSR) and Ad Hoc On-Demand Distance Vector Routing (AODV) in detail. DSR uses source routing by adding the complete route to packet headers. AODV maintains routing tables at nodes and relies on dynamically establishing next hop information for routes.
The document summarizes several routing protocols used in wireless networks. It discusses both table-driven protocols like DSDV and on-demand protocols like AODV. It provides details on how each protocol performs routing and maintains routes. It also outlines some advantages and disadvantages of protocols like DSDV, AODV, DSR, and TORA.
This document summarizes several reactive routing protocols for mobile ad hoc networks (MANETs). Reactive protocols create routes only when needed by a source. Dynamic Source Routing uses route requests and replies to find paths, while Temporally-Ordered Routing Algorithm builds and maintains a directed acyclic graph rooted at destinations. Some protocols aim to improve quality of service or support real-time data streams through techniques like bandwidth estimation and mobility prediction. Source Routing with Local Recovery reduces overhead by allowing intermediate nodes to perform local error recovery using route caches when possible.
Mac protocols for ad hoc wireless networks Divya Tiwari
The document discusses MAC protocols for ad hoc wireless networks. It addresses key issues in designing MAC protocols including limited bandwidth, quality of service support, synchronization, hidden and exposed terminal problems, error-prone shared channels, distributed coordination without centralized control, and node mobility. Common MAC protocol classifications and examples are also presented, such as contention-based protocols, sender-initiated versus receiver-initiated protocols, and protocols using techniques like reservation, scheduling, and directional antennas.
Lecture 19 22. transport protocol for ad-hoc Chandra Meena
This document discusses transport layer protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and the need for new network architectures and protocols to support new types of networks. It then provides an overview of TCP/IP and how TCP works, including congestion control mechanisms. The document discusses challenges for TCP over wireless networks, where packet losses are often due to errors rather than congestion. It covers different versions of TCP and their approaches to congestion control. The goal is to design transport layer protocols that can address the unreliable links and frequent topology changes in MANETs.
Black Hole Attack:
A malicious node advertises the wrong paths as good paths to the source node during the pathfinding process.
When the source selects the path including the attacker node, the traffic starts passing through the adversary node and this node starts dropping the packets selectively or in whole.
Black hole region is the entry point to a large number of harmful attacks.
he Optimized Link State Routing Protocol (OLSR)[1] is an IP routing protocol optimized for mobile ad hoc networks, which can also be used on other wireless ad hoc networks. OLSR is a proactive link-state routing protocol, which uses hello and topology control (TC) messages to discover and then disseminate link state information throughout the mobile ad hoc network. Individual nodes use this topology information to compute next hop destinations for all nodes in the network using shortest hop forwarding paths.
How to put these nodes together to form a meaningful network.
How a network should function at high-level application scenarios .
On the basis of these scenarios and optimization goals, the design of networking protocols in wireless sensor networks are derived
A proper service interface is required and integration of WSNs into larger network contexts.
This document discusses routing protocols for mobile ad-hoc networks (MANETs). It introduces several routing protocols including proactive (table-driven) protocols like Destination-Sequenced Distance Vector (DSDV), reactive (on-demand) protocols like Ad-hoc On-Demand Distance Vector (AODV) and Dynamic Source Routing (DSR), and hybrid protocols like Zone Routing Protocol (ZRP) that use both proactive and reactive approaches. For each protocol, it provides a brief overview of the routing approach and algorithm. It also compares the characteristics of proactive, reactive and hybrid routing protocols.
This document discusses clustering-based ad hoc routing protocols. It introduces the Clusterhead Gateway Switch Routing (CSGR) protocol, which uses a hierarchical network topology with mobile nodes grouped into clusters led by cluster heads. Each node maintains a cluster member table mapping nodes to cluster heads and a routing table to select the next hop towards the destination cluster head. The Least Cluster Change algorithm aims to minimize changes to cluster heads. The document provides an example routing from node 1 to node 12 and compares CSGR to the table-driven DSDV protocol.
Routing protocols for ad hoc wireless networks Divya Tiwari
The document discusses routing protocols for ad hoc wireless networks. It outlines several key challenges for these protocols, including mobility, bandwidth constraints, error-prone shared wireless channels, and hidden/exposed terminal problems. It also categorizes routing protocols based on how routing information is updated (proactively, reactively, or through a hybrid approach), whether they use past or future temporal network information, the type of network topology supported (flat or hierarchical), and how they account for specific resources like power.
ZRP divides routing into intrazone and interzone routing. Intrazone routing uses a proactive approach to route packets within a node's routing zone. Interzone routing uses a reactive approach where the source node sends route requests to peripheral nodes when the destination is outside its zone. The optimal zone radius depends on factors like mobility and query rates, with smaller radii preferred for higher mobility. ZRP aims to reduce routing overhead through techniques like restricting floods and maintaining multiple routes.
This document provides an overview of various topics related to the network layer, including IPv4, IPv6, ARP, RARP, mobile IP, routing algorithms, and routing protocols. It begins with basics of IPv4 such as its addressing scheme and role in interconnecting networks. IPv6 is then introduced, along with reasons for its development and key features like its large 128-bit addresses. Address Resolution Protocol (ARP) and Reverse ARP (RARP) are also covered. The document concludes by discussing routing algorithms like link-state and distance-vector, as well as protocols including RIP, OSPF, and BGP.
Transport control protocols for Wireless sensor networksRushin Shah
The document discusses traditional transport control protocols and their feasibility for use in wireless sensor networks. It describes how TCP and UDP are generally not suitable for WSNs due to their overhead and lack of features like congestion control that are needed in low power lossy networks. The document then outlines key considerations for designing new transport protocols for WSNs, including performing congestion control and reliable delivery, simplifying connection establishment, avoiding packet loss to reduce energy waste, and providing fairness across nodes. Transport protocols for WSNs need hop-by-hop approaches and mechanisms to reduce buffer usage and packet loss while conserving energy.
The Optimized Link State Routing Protocol (OLSR) is an IP routing protocol optimized for mobile ad hoc networks, which can also be used on other wireless ad hoc networks. OLSR uses hello and topology control (TC) messages to discover and then disseminate link state information throughout the mobile ad hoc network.
Contents which are covered here:
Classification of Ad-Hoc Routing Protocol
Link State Routing
Problems of Link State Routing
Optimized Link State Routing Protocol
1 Hop and 2 Hop Neighbors
Hello Packet
MPR Selection
Topology Table
MPR Information Declaration
*** Animated figure/diagram might not be visible in PDF view. Please consider it. ***
OLSR Model, OLSR Protocol, Optimized Link-State Routing Protocol
This document provides an overview of different routing protocols. It discusses IP routing, static routing, and dynamic routing. It also covers proactive routing protocols like DSDV which maintain routing tables and periodically update them. Reactive protocols like DSR and AODV establish routes on demand. Hybrid protocols combine proactive and reactive approaches. The document describes the key processes, advantages, and disadvantages of DSDV, DSR, AODV, and zone routing protocol.
This document discusses reactive routing protocols in mobile ad hoc networks (MANETs), focusing on the Ad Hoc On-Demand Distance Vector (AODV) protocol. It describes how AODV works by broadcasting Route Request packets when a route is needed, and nodes responding with Route Reply packets if they have a valid route. Intermediate nodes store the address of previous nodes to forward packets. The document outlines the key components of Route Request and Route Reply packets, and notes advantages of AODV such as on-demand route establishment and use of destination sequence numbers, with drawbacks including control overhead and bandwidth consumption from periodic beaconing.
The document summarizes contention-based MAC protocols for wireless sensor networks. It discusses the PAMAS protocol, which provides detailed overhearing avoidance and uses two channels - a data channel and control channel. Signaling packets like RTS, CTS, and busy tones are transmitted on the control channel. It also covers concepts like low duty cycles, wake up mechanisms, and protocols like S-MAC that coordinate node schedules to reduce idle listening. Quizzes are included to test understanding of discussed concepts.
LAR utilizes location information to improve routing efficiency by reducing control overhead. It uses GPS to obtain geographical information. There are two zones in LAR - the ExpectedZone where the destination is expected to be based on past location/mobility, and the RequestZone where routing packets can propagate. A RequestZone is created around the source and ExpectedZone, and routing requests are only forwarded to neighbors in this zone. Replies include current location, time, and sometimes speed. Intermediate nodes only forward if their distance to the destination is less than the source's distance. LAR reduces overhead but requires GPS, limiting its applicability.
Ad hoc wireless networks allow devices to connect and communicate with each other without a centralized access point. Nodes in an ad hoc network relay messages through intermediate hops to reach destinations. Examples include Bluetooth networks and wireless mesh networks. Issues in ad hoc networks include medium access control, routing with mobility and bandwidth constraints, and providing quality of service guarantees.
Routing, Different types of forwarding techniquerajib_
This document discusses different types of routing including direct, indirect, static, and dynamic routing. It describes the fields in a routing table including mask, network address, next hop address, interface, and others. Finally, it explains how routing tables are populated with routing information and provides an example routing table for a router.
The document summarizes the Ad Hoc On-Demand Distance Vector (AODV) routing protocol. AODV is a reactive routing protocol that uses route discovery cycles to find routes on demand. It uses sequence numbers to prevent loops and maintain freshness of routes. Routes are discovered and maintained through route request (RREQ), route reply (RREP), and route error (RERR) messages. When a route is needed, AODV floods RREQ messages and the destination or intermediate nodes reply with RREPs if they have a valid route. If a link breaks, RERR messages are propagated to invalidate routes using that link.
Routing Protocols for Ad-Hoc Networks. This is a book for Ad-hoc On-Demand Distance Vector Routing
&
DSR: The Dynamic Source Routing Protocol for Multi-Hop Wireless Ad Hoc Networks. November 2011,
Authors : Giorgos Papadakis & Manolis Surligas
The document summarizes several routing protocols used in wireless networks. It discusses both table-driven protocols like DSDV and on-demand protocols like AODV. It provides details on how each protocol performs routing and maintains routes. It also outlines some advantages and disadvantages of protocols like DSDV, AODV, DSR, and TORA.
This document summarizes several reactive routing protocols for mobile ad hoc networks (MANETs). Reactive protocols create routes only when needed by a source. Dynamic Source Routing uses route requests and replies to find paths, while Temporally-Ordered Routing Algorithm builds and maintains a directed acyclic graph rooted at destinations. Some protocols aim to improve quality of service or support real-time data streams through techniques like bandwidth estimation and mobility prediction. Source Routing with Local Recovery reduces overhead by allowing intermediate nodes to perform local error recovery using route caches when possible.
Mac protocols for ad hoc wireless networks Divya Tiwari
The document discusses MAC protocols for ad hoc wireless networks. It addresses key issues in designing MAC protocols including limited bandwidth, quality of service support, synchronization, hidden and exposed terminal problems, error-prone shared channels, distributed coordination without centralized control, and node mobility. Common MAC protocol classifications and examples are also presented, such as contention-based protocols, sender-initiated versus receiver-initiated protocols, and protocols using techniques like reservation, scheduling, and directional antennas.
Lecture 19 22. transport protocol for ad-hoc Chandra Meena
This document discusses transport layer protocols for mobile ad hoc networks (MANETs). It begins with an introduction to MANETs and the need for new network architectures and protocols to support new types of networks. It then provides an overview of TCP/IP and how TCP works, including congestion control mechanisms. The document discusses challenges for TCP over wireless networks, where packet losses are often due to errors rather than congestion. It covers different versions of TCP and their approaches to congestion control. The goal is to design transport layer protocols that can address the unreliable links and frequent topology changes in MANETs.
Black Hole Attack:
A malicious node advertises the wrong paths as good paths to the source node during the pathfinding process.
When the source selects the path including the attacker node, the traffic starts passing through the adversary node and this node starts dropping the packets selectively or in whole.
Black hole region is the entry point to a large number of harmful attacks.
he Optimized Link State Routing Protocol (OLSR)[1] is an IP routing protocol optimized for mobile ad hoc networks, which can also be used on other wireless ad hoc networks. OLSR is a proactive link-state routing protocol, which uses hello and topology control (TC) messages to discover and then disseminate link state information throughout the mobile ad hoc network. Individual nodes use this topology information to compute next hop destinations for all nodes in the network using shortest hop forwarding paths.
How to put these nodes together to form a meaningful network.
How a network should function at high-level application scenarios .
On the basis of these scenarios and optimization goals, the design of networking protocols in wireless sensor networks are derived
A proper service interface is required and integration of WSNs into larger network contexts.
This document discusses routing protocols for mobile ad-hoc networks (MANETs). It introduces several routing protocols including proactive (table-driven) protocols like Destination-Sequenced Distance Vector (DSDV), reactive (on-demand) protocols like Ad-hoc On-Demand Distance Vector (AODV) and Dynamic Source Routing (DSR), and hybrid protocols like Zone Routing Protocol (ZRP) that use both proactive and reactive approaches. For each protocol, it provides a brief overview of the routing approach and algorithm. It also compares the characteristics of proactive, reactive and hybrid routing protocols.
This document discusses clustering-based ad hoc routing protocols. It introduces the Clusterhead Gateway Switch Routing (CSGR) protocol, which uses a hierarchical network topology with mobile nodes grouped into clusters led by cluster heads. Each node maintains a cluster member table mapping nodes to cluster heads and a routing table to select the next hop towards the destination cluster head. The Least Cluster Change algorithm aims to minimize changes to cluster heads. The document provides an example routing from node 1 to node 12 and compares CSGR to the table-driven DSDV protocol.
Routing protocols for ad hoc wireless networks Divya Tiwari
The document discusses routing protocols for ad hoc wireless networks. It outlines several key challenges for these protocols, including mobility, bandwidth constraints, error-prone shared wireless channels, and hidden/exposed terminal problems. It also categorizes routing protocols based on how routing information is updated (proactively, reactively, or through a hybrid approach), whether they use past or future temporal network information, the type of network topology supported (flat or hierarchical), and how they account for specific resources like power.
ZRP divides routing into intrazone and interzone routing. Intrazone routing uses a proactive approach to route packets within a node's routing zone. Interzone routing uses a reactive approach where the source node sends route requests to peripheral nodes when the destination is outside its zone. The optimal zone radius depends on factors like mobility and query rates, with smaller radii preferred for higher mobility. ZRP aims to reduce routing overhead through techniques like restricting floods and maintaining multiple routes.
This document provides an overview of various topics related to the network layer, including IPv4, IPv6, ARP, RARP, mobile IP, routing algorithms, and routing protocols. It begins with basics of IPv4 such as its addressing scheme and role in interconnecting networks. IPv6 is then introduced, along with reasons for its development and key features like its large 128-bit addresses. Address Resolution Protocol (ARP) and Reverse ARP (RARP) are also covered. The document concludes by discussing routing algorithms like link-state and distance-vector, as well as protocols including RIP, OSPF, and BGP.
Transport control protocols for Wireless sensor networksRushin Shah
The document discusses traditional transport control protocols and their feasibility for use in wireless sensor networks. It describes how TCP and UDP are generally not suitable for WSNs due to their overhead and lack of features like congestion control that are needed in low power lossy networks. The document then outlines key considerations for designing new transport protocols for WSNs, including performing congestion control and reliable delivery, simplifying connection establishment, avoiding packet loss to reduce energy waste, and providing fairness across nodes. Transport protocols for WSNs need hop-by-hop approaches and mechanisms to reduce buffer usage and packet loss while conserving energy.
The Optimized Link State Routing Protocol (OLSR) is an IP routing protocol optimized for mobile ad hoc networks, which can also be used on other wireless ad hoc networks. OLSR uses hello and topology control (TC) messages to discover and then disseminate link state information throughout the mobile ad hoc network.
Contents which are covered here:
Classification of Ad-Hoc Routing Protocol
Link State Routing
Problems of Link State Routing
Optimized Link State Routing Protocol
1 Hop and 2 Hop Neighbors
Hello Packet
MPR Selection
Topology Table
MPR Information Declaration
*** Animated figure/diagram might not be visible in PDF view. Please consider it. ***
OLSR Model, OLSR Protocol, Optimized Link-State Routing Protocol
This document provides an overview of different routing protocols. It discusses IP routing, static routing, and dynamic routing. It also covers proactive routing protocols like DSDV which maintain routing tables and periodically update them. Reactive protocols like DSR and AODV establish routes on demand. Hybrid protocols combine proactive and reactive approaches. The document describes the key processes, advantages, and disadvantages of DSDV, DSR, AODV, and zone routing protocol.
This document discusses reactive routing protocols in mobile ad hoc networks (MANETs), focusing on the Ad Hoc On-Demand Distance Vector (AODV) protocol. It describes how AODV works by broadcasting Route Request packets when a route is needed, and nodes responding with Route Reply packets if they have a valid route. Intermediate nodes store the address of previous nodes to forward packets. The document outlines the key components of Route Request and Route Reply packets, and notes advantages of AODV such as on-demand route establishment and use of destination sequence numbers, with drawbacks including control overhead and bandwidth consumption from periodic beaconing.
The document summarizes contention-based MAC protocols for wireless sensor networks. It discusses the PAMAS protocol, which provides detailed overhearing avoidance and uses two channels - a data channel and control channel. Signaling packets like RTS, CTS, and busy tones are transmitted on the control channel. It also covers concepts like low duty cycles, wake up mechanisms, and protocols like S-MAC that coordinate node schedules to reduce idle listening. Quizzes are included to test understanding of discussed concepts.
LAR utilizes location information to improve routing efficiency by reducing control overhead. It uses GPS to obtain geographical information. There are two zones in LAR - the ExpectedZone where the destination is expected to be based on past location/mobility, and the RequestZone where routing packets can propagate. A RequestZone is created around the source and ExpectedZone, and routing requests are only forwarded to neighbors in this zone. Replies include current location, time, and sometimes speed. Intermediate nodes only forward if their distance to the destination is less than the source's distance. LAR reduces overhead but requires GPS, limiting its applicability.
Ad hoc wireless networks allow devices to connect and communicate with each other without a centralized access point. Nodes in an ad hoc network relay messages through intermediate hops to reach destinations. Examples include Bluetooth networks and wireless mesh networks. Issues in ad hoc networks include medium access control, routing with mobility and bandwidth constraints, and providing quality of service guarantees.
Routing, Different types of forwarding techniquerajib_
This document discusses different types of routing including direct, indirect, static, and dynamic routing. It describes the fields in a routing table including mask, network address, next hop address, interface, and others. Finally, it explains how routing tables are populated with routing information and provides an example routing table for a router.
The document summarizes the Ad Hoc On-Demand Distance Vector (AODV) routing protocol. AODV is a reactive routing protocol that uses route discovery cycles to find routes on demand. It uses sequence numbers to prevent loops and maintain freshness of routes. Routes are discovered and maintained through route request (RREQ), route reply (RREP), and route error (RERR) messages. When a route is needed, AODV floods RREQ messages and the destination or intermediate nodes reply with RREPs if they have a valid route. If a link breaks, RERR messages are propagated to invalidate routes using that link.
Routing Protocols for Ad-Hoc Networks. This is a book for Ad-hoc On-Demand Distance Vector Routing
&
DSR: The Dynamic Source Routing Protocol for Multi-Hop Wireless Ad Hoc Networks. November 2011,
Authors : Giorgos Papadakis & Manolis Surligas
This document provides an overview and summary of networking technologies for Internet of Things applications. It discusses the roles and functions of network modules, common routing techniques like flooding, distance vector routing, and source routing. It then describes two specific routing protocols - Ad Hoc On-demand Distance Vector (AODV) routing and the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). AODV uses an on-demand approach to route discovery, while RPL is a proactive protocol that constructs a destination-oriented directed acyclic graph to route packets from nodes to the root. The document also discusses topology maintenance and the use of Trickle timers in RPL.
This document provides an overview and summary of networking technologies for Internet of Things applications. It discusses the roles and functions of network modules, common routing techniques like flooding, distance vector routing, and source routing. It then describes two specific routing protocols - Ad Hoc On-demand Distance Vector (AODV) routing and the IPv6 Routing Protocol for Low-Power and Lossy Networks (RPL). AODV uses an on-demand approach to route discovery, while RPL is a proactive protocol that builds a destination oriented directed acyclic graph to route packets from nodes to the root. The document also discusses topology maintenance and the use of Trickle timers in RPL.
This document discusses flooding and dynamic source routing (DSR) for data delivery in mobile computing. It describes how flooding works, including its advantages of simplicity and potential higher reliability but disadvantages of high overhead and potential lower reliability. It then covers how DSR uses route discovery by flooding route request messages, route replies sent back to the source, and route caching to optimize routing with advantages of on-demand routing and reduced overhead.
DSDV is a proactive routing protocol that uses periodic routing table exchanges and sequence numbers to avoid loops. AODV is a reactive protocol based on DSDV that uses on-demand route discovery with broadcast RREQ and unicast RREP messages to find routes, and maintains routing tables at nodes instead of in packet headers like DSR. Both protocols aim to quickly adapt to dynamic links with low overhead.
Comparison of different MANET routing protocols in wireless ADHOCAmitoj Kaur
In this project, AODV and Flooding routing protocols using different parameter metrics have been simulated and analyzed
Simulation results show that performance parameters of the routing protocols may vary depending on network load, mobility and network size.
Under G-Sense Model, AODV experience the highest Packet Delivery Fraction and Throughput with the increase of nodes stop time, and mobile nodes number.
AODV and Simple Flooding performance is due to their on demand characteristics to determine the freshness of the route. And it is proved also that AODV has a slightly higher Average end-to-end Delay than Simple Flooding.
The document discusses routing protocols for mobile ad hoc networks (MANETs). It begins by defining MANETs and their unique characteristics, such as moving nodes, wireless links, and power constraints. Some key challenges for MANET routing protocols are the need for dynamic routing due to frequent topology changes and minimizing routing overhead. The document then discusses various categories of MANET routing protocols, including reactive protocols like DSR and AODV, proactive protocols, and hybrid and location-based protocols. It provides more detailed explanations of the route discovery and maintenance processes for DSR and AODV.
Mobile Ad-hoc Network (MANET) Routing Algorithms─ Part 1Sushant Kushwaha
DSR deploys source routing, reacting dynamically to changes by maintaining only active routing addresses from source to destination. AODV is also a reactive protocol that maintains only active routes, with each node keeping a next-hop routing table. Route entries expire after a time limit. AODV adopts destination sequence numbers to ensure loop-free and up-to-date routes.
This document discusses MANET routing protocols and compares AODV and DSR protocols. It provides an overview of ad hoc networks and their key characteristics like being decentralized and relying on participating nodes to forward data. It then describes the main categories of ad hoc routing protocols - proactive (table-driven) and reactive (on-demand). The document dives deeper into AODV and DSR protocols, explaining their path discovery, maintenance and other mechanisms. The key differences noted are that DSR can handle uni-directional and bi-directional links while both protocols employ on-demand routing and broadcast discovery but use different approaches for route information storage and link failure handling.
This document discusses different types of routing protocols for mobile ad hoc networks. It begins by classifying routing protocols into four categories: proactive (table-driven), reactive (on-demand), hybrid, and geographic location-assisted. It then provides more details on proactive protocols like DSDV, and reactive protocols like DSR and AODV. For DSDV, it describes how routing tables are regularly exchanged and updated when link breaks occur. For DSR and AODV, it explains how routes are discovered on-demand via route requests and replies. Key differences between DSR and AODV are also summarized.
This document provides an overview of the Dynamic Source Routing (DSR) protocol for mobile ad hoc networks. DSR is a reactive, on-demand routing protocol that uses route discovery and route maintenance through flooding of route request and route reply packets. Key aspects covered include: how DSR performs route discovery by broadcasting route requests; how the destination responds with a route reply listing the full end-to-end path; how nodes cache routes for potential future use; and how route errors trigger new route discovery if needed. DSR optimization through aggressive route caching is also discussed to speed up routing.
The document discusses different types of wireless networks including infrastructure-based networks like cellular systems and wireless LANs, as well as ad hoc networks that do not require fixed infrastructure. Ad hoc networks are useful when infrastructure is not available, practical, or affordable. The document outlines key challenges with ad hoc networks like frequent topology changes, multi-hop routing, and node mobility. It then summarizes two popular routing protocols for ad hoc networks - AODV which uses flooding for route discovery and DSR which allows source routing by caching route information in packet headers.
AODV is an on-demand routing protocol for mobile ad-hoc networks that uses route discovery and route maintenance to dynamically discover routes. When a source node needs to send a packet to a destination, it broadcasts a route request which is forwarded through the network until it reaches the destination or an intermediate node with a fresh route. The destination or intermediate node then sends back a route reply along the reverse path set up by the route request, which is used to forward data packets. Nodes maintain routing tables with only active routes and expired routes are deleted to avoid unnecessary overhead.
AODV is a reactive routing protocol for mobile ad hoc networks. It uses route discovery and maintenance to dynamically discover and maintain routes. Route discovery uses route request (RREQ) and route reply (RREP) messages to find routes between nodes. Route maintenance uses route error (RERR) messages to notify nodes of link breaks. Each node maintains a routing table with next hop and destination information.
implementation of sinkhole attack on DSR protocolAtul Atalkar
This document outlines a dissertation seminar on implementing a sinkhole attack in the DSR routing protocol for mobile ad hoc networks (MANETs). It begins with introductions to MANETs and the DSR protocol, explaining their key characteristics and operations. The document then discusses sinkhole attacks, how they work in DSR networks, and their impacts on network performance metrics like packet delivery ratio and end-to-end delay. It proposes using the ns-2 network simulator to model and analyze the effects of sinkhole attacks on DSR routing in MANETs.
The document discusses various network layer services and routing algorithms. It describes packet switching which allows packets to be forwarded using destination addresses and connection-oriented services which require call setup and use virtual circuit identifiers. It also summarizes different routing algorithms including flooding, distance vector, link state, hierarchical routing, multicast routing, and routing for mobile and ad hoc networks.
Default and On demand routing - Advance Computer NetworksSonali Parab
Routing is the process of selecting best paths in a network. In the past, the term routing was also used to mean forwarding network traffic among networks. However this latter function is much better described as simply forwarding. Routing is performed for many kinds of networks, including the telephone network (circuit switching), electronic data networks (such as the Internet), and transportation networks.
In packet switching networks, routing directs packet forwarding (the transit of logically addressed network packets from their source toward their ultimate destination) through intermediate nodes. Intermediate nodes are typically network hardware devices such as routers, bridges, gateways, firewalls, or switches. General-purpose computers can also forward packets and perform routing, though they are not specialized hardware and may suffer from limited performance. The routing process usually directs forwarding on the basis of routing tables which maintain a record of the routes to various network destinations. Thus, constructing routing tables, which are held in the router's memory, is very important for efficient routing. Most routing algorithms use only one network path at a time. Multipath routing techniques enable the use of multiple alternative paths.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
Software Engineering and Project Management - Introduction, Modeling Concepts...Prakhyath Rai
Introduction, Modeling Concepts and Class Modeling: What is Object orientation? What is OO development? OO Themes; Evidence for usefulness of OO development; OO modeling history. Modeling
as Design technique: Modeling, abstraction, The Three models. Class Modeling: Object and Class Concept, Link and associations concepts, Generalization and Inheritance, A sample class model, Navigation of class models, and UML diagrams
Building the Analysis Models: Requirement Analysis, Analysis Model Approaches, Data modeling Concepts, Object Oriented Analysis, Scenario-Based Modeling, Flow-Oriented Modeling, class Based Modeling, Creating a Behavioral Model.
Embedded machine learning-based road conditions and driving behavior monitoringIJECEIAES
Car accident rates have increased in recent years, resulting in losses in human lives, properties, and other financial costs. An embedded machine learning-based system is developed to address this critical issue. The system can monitor road conditions, detect driving patterns, and identify aggressive driving behaviors. The system is based on neural networks trained on a comprehensive dataset of driving events, driving styles, and road conditions. The system effectively detects potential risks and helps mitigate the frequency and impact of accidents. The primary goal is to ensure the safety of drivers and vehicles. Collecting data involved gathering information on three key road events: normal street and normal drive, speed bumps, circular yellow speed bumps, and three aggressive driving actions: sudden start, sudden stop, and sudden entry. The gathered data is processed and analyzed using a machine learning system designed for limited power and memory devices. The developed system resulted in 91.9% accuracy, 93.6% precision, and 92% recall. The achieved inference time on an Arduino Nano 33 BLE Sense with a 32-bit CPU running at 64 MHz is 34 ms and requires 2.6 kB peak RAM and 139.9 kB program flash memory, making it suitable for resource-constrained embedded systems.
Discover the latest insights on Data Driven Maintenance with our comprehensive webinar presentation. Learn about traditional maintenance challenges, the right approach to utilizing data, and the benefits of adopting a Data Driven Maintenance strategy. Explore real-world examples, industry best practices, and innovative solutions like FMECA and the D3M model. This presentation, led by expert Jules Oudmans, is essential for asset owners looking to optimize their maintenance processes and leverage digital technologies for improved efficiency and performance. Download now to stay ahead in the evolving maintenance landscape.
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
Null Bangalore | Pentesters Approach to AWS IAMDivyanshu
#Abstract:
- Learn more about the real-world methods for auditing AWS IAM (Identity and Access Management) as a pentester. So let us proceed with a brief discussion of IAM as well as some typical misconfigurations and their potential exploits in order to reinforce the understanding of IAM security best practices.
- Gain actionable insights into AWS IAM policies and roles, using hands on approach.
#Prerequisites:
- Basic understanding of AWS services and architecture
- Familiarity with cloud security concepts
- Experience using the AWS Management Console or AWS CLI.
- For hands on lab create account on [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
# Scenario Covered:
- Basics of IAM in AWS
- Implementing IAM Policies with Least Privilege to Manage S3 Bucket
- Objective: Create an S3 bucket with least privilege IAM policy and validate access.
- Steps:
- Create S3 bucket.
- Attach least privilege policy to IAM user.
- Validate access.
- Exploiting IAM PassRole Misconfiguration
-Allows a user to pass a specific IAM role to an AWS service (ec2), typically used for service access delegation. Then exploit PassRole Misconfiguration granting unauthorized access to sensitive resources.
- Objective: Demonstrate how a PassRole misconfiguration can grant unauthorized access.
- Steps:
- Allow user to pass IAM role to EC2.
- Exploit misconfiguration for unauthorized access.
- Access sensitive resources.
- Exploiting IAM AssumeRole Misconfiguration with Overly Permissive Role
- An overly permissive IAM role configuration can lead to privilege escalation by creating a role with administrative privileges and allow a user to assume this role.
- Objective: Show how overly permissive IAM roles can lead to privilege escalation.
- Steps:
- Create role with administrative privileges.
- Allow user to assume the role.
- Perform administrative actions.
- Differentiation between PassRole vs AssumeRole
Try at [killercoda.com](https://killercoda.com/cloudsecurity-scenario/)
1. 4-1
Ad hoc On Demand Distance
Vector (AODV) Routing Protocol
CS: 647
Advanced Topics in Wireless Networks
Dr. Baruch Awerbuch & Dr. Amitabh Mishra
Department of Computer Science
Johns Hopkins
2. 4-2
Reading
❒ Chapter 6, Sections 6.1-6.3, 6.5 – Ad Hoc
Networking, Perkins, Addison Wesley, 2001
4. 4-4
Introduction: DSDV vs. AODV
❒ In AODV such broadcasts are
not necessary
❒ If a link breakage does not
affect on going transmission ->
no global broadcast occurs
❒ Only affected nodes are
informed
❒ Local movements of nodes
have local effects
❒ AODV reduces the network
wide broadcasts to the extent
possible
❒ Significant reduction in
control overhead as compared
to DSDV
❒ DSDV broadcasts every
change in the network to
every node
❒ When two neighbors enter
communication range of each
other
❍ This results in a network wide
broadcast
❒ Similarly when two nodes drift
apart from each other’s range
–> link breakage
❍ Also results in a network wide
broadcast
❒ Local movements have global
effects
5. 4-5
Ad Hoc On Demand Distance-
Vector (AODV) Routing (1)
❒ Reactive or on Demand
❒ Descendant of DSDV
❒ Uses bi-directional links
❒ Route discovery cycle used for route
finding
❒ Maintenance of active routes
❒ Sequence numbers used for loop prevention
and as route freshness criteria
❒ Provides unicast and multicast
communication
6. 4-6
Ad Hoc On Demand Distance-
Vector (AODV) Routing (2)
❒ Whenever routes are not used -> get expired ->
Discarded
❍ Reduces stale routes
❍ Reduces need for route maintenance
❒ Minimizes number of active routes between an
active source and destination
❒ Can determine multiple routes between a source
and a destination, but implements only a single
route, because
❍ Difficult to manage multiple routes between same
source/destination pair
❍ If one route breaks, its difficult to know whether other
route is available
❍ Lot of book-keeping involved
7. 4-7
AODV Properties (1)
1. AODV discovers routes as and when
necessary
❒ Does not maintain routes from every node to
every other
2. Routes are maintained just as long as
necessary
3. Every node maintains its monotonically
increasing sequence number -> increases
every time the node notices change in the
neighborhood topology
8. 4-8
AODV Properties (2)
❒ AODV utilizes routing tables to store routing
information
1. A Routing table for unicast routes
2. A Routing table for multicast routes
❒ The route table stores: <destination addr, next-hop addr,
destination sequence number, life_time>
❒ For each destination, a node maintains a list of
precursor nodes, to route through them
❍ Precusor nodes help in route maintenance (more later)
❒ Life-time updated every time the route is used
❍ If route not used within its life time -> it expires
9. 4-9
AODV – Route Discovery (1)
❒ When a node wishes to send a packet to some
destination –
❍ It checks its routing table to determine if it has a
current route to the destination
• If Yes, forwards the packet to next hop node
• If No, it initiates a route discovery process
❒ Route discovery process begins with the creation
of a Route Request (RREQ) packet -> source node
creates it
❒ The packet contains – source node’s IP address,
source node’s current sequence number,
destination IP address, destination sequence
number
10. 4-10
AODV – Route Discovery (2)
❒ Packet also contains broadcast ID number
❍ Broadcast ID gets incremented each time a source node
uses RREQ
❍ Broadcast ID and source IP address form a unique
identifier for the RREQ
❒ Broadcasting is done via Flooding
12. 4-12
Flooding for Control Packet Delivery
❒ Sender S broadcasts a control packet P to
all its neighbors
❒ Each node receiving P forwards P to its
neighbors
❒ Sequence numbers help to avoid the
possibility of forwarding the same packet
more than once
❒ Packet P reaches destination D provided
that D is reachable from sender S
❒ Node D does not forward the packet
13. 4-13
Flooding for Control Packet
Delivery - Example
B
A
S E
F
H
J
D
C
G
I
K
Represents that connected nodes are within each
other’s transmission range
Z
Y
Represents a node that has received packet P
M
N
L
14. 4-14
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Represents transmission of packet P
Represents a node that receives packet P for
the first time
Z
Y
Broadcast transmission
M
N
L
15. 4-15
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Node H receives packet P from two neighbors:
potential for collision
Z
Y
M
N
L
16. 4-16
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Node C receives packet P from G and H, but does not forward
it again, because node C has already forwarded packet P once
Z
Y
M
N
L
17. 4-17
Flooding for Control packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
M
Nodes J and K both broadcast packet P to node D
Since nodes J and K are hidden from each other, their
transmissions may collide
=> Packet P may not be delivered to node D at all,
despite the use of flooding
N
L
18. 4-18
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
Node D does not forward packet P, because node D
is the intended destination of packet P
M
N
L
19. 4-19
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Flooding completed
Nodes unreachable from S do not receive packet P (e.g., node Z)
Nodes for which paths go through the destination D
also do not receive packet P (example: node N)
Z
Y
M
N
L
20. 4-20
Flooding for Control Packet
Delivery
B
A
S E
F
H
J
D
C
G
I
K
Flooding may deliver packets to too many nodes
(in the worst case, all nodes reachable from sender
may receive the packet)
Z
Y
M
N
L
21. 4-21
Flooding of Control Packets - Summary
❒ Many protocols perform flooding of control
packets e.g. AODV & DSR, instead of data packets
❒ The control packets are used to discover routes
❒ Discovered routes are subsequently used to send
data packet(s)
❒ Overhead of control packet flooding is amortized
over data packets transmitted between
consecutive control packet floods
22. 4-22
Flooding for Data Delivery -Advantages
❒ Simplicity
❒ May be more efficient than other protocols when
rate of information transmission is low enough
that the overhead of explicit route discovery and
maintenance incurred by other protocols is
relatively higher
❍ this scenario may occur, for instance, when nodes
transmit small data packets relatively infrequently, and
many topology changes occur between consecutive packet
transmissions
❒ Potentially higher reliability of data delivery
❍ Because packets may be delivered to the destination on
multiple paths
23. 4-23
Flooding for Data Delivery -
Disadvantages
❒ Potentially, very high overhead
❍ Data packets may be delivered to too many
nodes who do not need to receive them
❒ Potentially lower reliability of data delivery
❍ Flooding uses broadcasting -- hard to implement
reliable broadcast delivery without significantly
increasing overhead
– Broadcasting in IEEE 802.11 MAC is unreliable
❍ In this example, nodes J and K may transmit to
node D simultaneously, resulting in loss of the
packet
– in this case, destination would not receive the
packet at all
24. 4-24
Route Discovery (Contd.)
❒ Once an intermediate node receives a RREQ, the
node sets up a reverse route entry for the
source node in its route table
❍ Reverse route entry consists of <Source IP
address, Source seq. number, number of hops to source node,
IP address of node from which RREQ was received>
❍ Using the reverse route a node can send a
RREP (Route Reply packet) to the source
• Reverse route entry also contains – life time field
❒ RREQ reaches destination -> In order to respond
to RREQ a node should have in its route table:
1. Unexpired entry for the destination
2. Seq. number of destination at least as great as in RREQ (for
loop prevention)
25. 4-25
Route Discovery (Contd.)
❒ RREQ reaches destination (contd.)
❍ If both conditions are met & the IP address of
the destination matches with that in RREQ
the node responds to RREQ by sending a RREP
back using unicasting and not flooding to the
source using reverse path
❍ If conditions are not satisfied, then node
increments the hop count in RREQ and
broadcasts to its neighbors
❒ Ultimately the RREQ will make to the
destination
26. 4-26
AODV – Route Discovery - Example
1. Node S needs a route to D
SS
DDCC
BB
AA
27. 4-27
AODV – Route Discovery
1. Node S needs a route to D
2. Creates a Route Request (RREQ)
❍ Enters D’s IP addr, seq#, S’s IP addr, seq#, hopcount
(=0)
SS
DDCC
BB
AA
28. 4-28
AODV – Route Discovery
1. Node S needs a route to D
2. Creates a Route Request (RREQ)
❍ Enters D’s IP addr, seq#, S’s IP addr, seq#, hopcount
(=0)
3. Node S broadcasts RREQ to neighbors
SS
DDCC
BB
AA
RREQ
29. 4-29
AODV – Route Discovery
4. Node A receives RREQ
❍ Makes a reverse route entery for S
dest=S, nexthop=S, hopcount=1
❍ It has no routes to D, so it rebroadcasts RREQ
SS
DDCC
BB
AA
RREQ
30. 4-30
AODV – Route Discovery
4. Node A receives RREQ
❍ Makes a reverse route entery for S
dest=S, nexthop=S, hopcount=1
❍ It has no routes to D, so it rebroadcasts RREQ
SS
DDCC
BB
AA
RREQ
31. 4-31
AODV – Route Discovery
5. Node C receives RREQ
❍ Makes a reverse route entry for S
dest=S, nexthop=A, hopcount=2
❍ It has a route to D, and the seq# for route to D is >= D’s
seq# in RREQ
SS
DDCC
BB
AA
RREQ
32. 4-32
Route Reply in AODV - Comments
❒ An intermediate node (not the destination) may
also send a Route Reply (RREP) provided that it
knows a more recent path than the one previously
known to sender S
❒ To determine whether the path known to an intermediate
node is more recent, destination sequence numbers are used
❒ The likelihood that an intermediate node will send a Route
Reply when using AODV not as high as DSR (Later)
❍ A new Route Request by node S for a destination is
assigned a higher destination sequence number. An
intermediate node which knows a route, but with a
smaller sequence number, cannot send Route Reply
33. 4-33
AODV – Route Discovery
5. Node C receives RREQ (Cont.)
❍ C creates a Route Reply (RREP)
Enters D’s IP addr, seq#, S’s IP addr, hopcount to D
(=1)
❍ Unicasts RREP to A
SS
DDCC
BB
AA
RREQ
34. 4-34
AODV – Route Discovery
5. Node C receives RREQ (Cont.)
❍ C creates a Route Reply (RREP)
Enters D’s IP addr, seq#, S’s IP addr, hopcount to D
(=1)
❍ Unicasts RREP to A
SS
DDCC
BB
AA
RREP
35. 4-35
AODV – Forward Path Setup
5. Node A receives RREP
❍ Makes a forward route entry to D
dest=D, nexthop=C, hopcount=2
❍ Unicasts RREP to S
SS
DDCC
BB
AA
RREP
RREP
36. 4-36
Forward Path Setup (1)
❒ When a node determines that it has a current
route to respond to RREQ i.e. has a path to
destination – It creates RREP (Route Reply)
❒ RREP contains <IP address of source and
destination>
❍ If RREP is being sent by destination
• The RREP will also contain the <current sqn # of
destination, hop-count=0, life-time>
❍ If RREP is sent by an intermediate node
• RREP will contain its record of the <destination
sequence number, hop-count=its distance to
destination, its value of the life-time>
37. 4-37
Forward Path Setup (2)
❒ When an intermediate node receives the RREP, it
sets up a forward path entry to the destination in
its route table
❍ Forward path entry contains
<IP Address of destination, IP address of node from which
the entry arrived, hop-count to destination, life-time>
❍ To obtain its distance to destination i.e. hop-count, a
node increments its distance by 1
❍ If route is not used within the life time, its deleted
❒ After processing the RREP, the node forwards it
towards the source
38. 4-38
AODV – Forward Path Setup
5. Node S receives RREP
❍ Makes a forward route entry to D
dest=D, nexthop =A, hopcount = 3
SS
DDCC
BB
AA
RREP
39. 4-39
Receipt of Multiple RREP
❒ A node may receive multiple RREP for a
given destination from more than one
neighbor
❍ The node only forwards the first RREP it
receives
❍ May forward another RREP if that has greater
destination sequence number or a smaller hop
count
❍ Rest are discarded -> reduces the number of
RREP propagating towards the source
❒ Source can begin data transmission upon
receiving the first RREP
40. 4-40
AODV – Data Delivery
5. Node S receives RREP
❍ Makes a forward route entry to D
dest=D, nexthop =A, hopcount = 3
❍ Sends data packet on route to D
SS
DDCC
BB
AA
41. 4-41
Example 2: Route Requests in
AODV
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
Represents a node that has received RREQ for D from S
M
N
L
42. 4-42
Route Requests in AODV
B
A
S E
F
H
J
D
C
G
I
K
Represents transmission of RREQ
Z
Y
Broadcast transmission
M
N
L
43. 4-43
Route Requests in AODV
B
A
S E
F
H
J
D
C
G
I
K
Represents links on Reverse Path
Z
Y
M
N
L
44. 4-44
Reverse Path Setup in AODV
B
A
S E
F
H
J
D
C
G
I
K
Node C receives RREQ from G and H, but does not forward
it again, because node C has already forwarded RREQ once
Z
Y
M
N
L
46. 4-46
Reverse Path Setup in AODV
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
Node D does not forward RREQ, because node D
is the intended target of the RREQ
M
N
L
47. 4-47
Route Reply in AODV
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
Represents links on path taken by RREP
M
N
L
48. 4-48
Forward Path Setup in AODV
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
M
N
L
Forward links are setup when RREP travels along
the reverse path
Represents a link on the forward path
49. 4-49
Data Delivery in AODV
B
A
S E
F
H
J
D
C
G
I
K
Z
Y
M
N
L
Routing table entries used to forward data packet.
Route is not included in packet header.
DATA
50. 4-50
Timeouts
❒ A routing table entry maintaining a reverse path is
purged after a timeout interval
❍ timeout should be long enough to allow RREP to
come back
❒ A routing table entry maintaining a forward path is
purged if not used for a active_route_timeout
interval
❍ if no is data being sent using a particular routing table
entry, that entry will be deleted from the routing table
(even if the route may actually still be valid)
52. 4-52
Link Failure Reporting
❒ A neighbor of node X is considered active for a
routing table entry if the neighbor sent a packet
within active_route_timeout interval and was
forwarded using that entry
❒ If a source node moves, a new route discovery
process is initiated
❒ If intermediate nodes or the destination move ->
❍ The next hop links break resulting in link failures
❍ Routing tables are updated for the link filaures
❍ All active neighbors are informed by RERR message
53. 4-53
Route Maintenance - RERR
❒ RERR is initiated by the node upstream
(closer to the source) of the break
❍ Its propagated to all the affected destinations
❍ RERR lists all the nodes affected by the link
failure -> Nodes that were using the link to
route messages (precursor nodes)
❍ When a node receives an RERR, it marks its
route to the destination as invalid -> Setting
distance to the destination as infinity in the
route table
❒ When a source node receives an RRER, it
can reinitiate the route discovery
54. 4-54
AODV – Route Maintenance- Example
1. Link between C and D breaks
2. Node C invalidates route to D in route table
3. Node C creates Route Error message
❒ Lists all destinations that are now unreachable
❒ Sends to upstream neighbors
SS
DDCC
BB
AA
X
RERR
55. 4-55
AODV – Route Maintenance -
Example
4. Node A receives RERR
❒ Checks whether C is its next hop on route to D
❒ Deletes route to D (makes distance -> infinity)
❒ Forwards RERR to S
SS
DDCC
BB
AA
RERR
RERR
56. 4-56
AODV – Route Maintenance-
Example
5. Node S receives RERR
❒ Checks whether A is its next hop on route to D
❒ Deletes route to D
❒ Rediscovers route if still needed
SS
DDCC
BB
AA
RERR
57. 4-57
Route Error
❒ When node X is unable to forward packet P (from
node S to node D) on link (X,Y), it generates a
RERR message
❒ Node X increments the destination sequence
number for D cached at node X
❒ The incremented sequence number N is included in
the RERR
❒ When node S receives the RERR, it initiates a new
route discovery for D using destination sequence
number at least as large as N
58. 4-58
Destination Sequence Number
❒ Continuing from the previous slide …
❒ When node D receives the route request
with destination sequence number N, node
D will set its sequence number to N, unless
it is already larger than N
60. 4-60
Link Failure Detection
❒ Hello messages: Neighboring nodes
periodically exchange hello message
❒ Absence of hello message is used as an
indication of link failure
❒ Alternatively, failure to receive several
MAC-level acknowledgements may be used
as an indication of link failure
61. 4-61
Why Sequence Numbers in AODV
❒ To avoid using old/broken routes
❍ To determine which route is newer
❒ To prevent formation of loops
❍ A had a route to D initially
❍ Assume that A does not know about failure of link C-D
because RERR sent by C is lost
❍ Now C performs a route discovery for D. Node A
receives the RREQ (say, via path C-E-A)
❍ Node A will reply since A knows a route to D via node B
❍ Results in a loop (for instance, C-E-A-B-C )
A B C D
E
62. 4-62
Why Sequence Numbers in
AODV
❍ Loop C-E-A-B-C
❍ But because of usage of sequence number, A
will not use the route A-B-C, because the
sequence numbers will be lower than what A
receives from A
A B C D
E
63. 4-63
Optimizations
❒ Route Requests are initially sent with small
Time-to-Live (TTL) field, to limit their
propagation
❍ DSR also includes a similar optimization
❒ If no Route Reply is received, then larger
TTL tried
64. 4-64
AODV: Optimizations
❒ Expanding Ring Search
❍ Prevents flooding of network during route
discovery
❍ Control Time to Live (TTL) of RREQ to search
incrementally larger areas of network
❍ Advantages: Less overhead when successful
❍ Disadvantages: Longer delay if route not found
immediately
65. 4-65
AODV: Optimizations (Cont.)
❒ Local Repairs
❍ Repair breaks in active routes locally instead of
notifying source
❍ Use small TTL because destination probably
hasn’t moved far
❍ If first repair attempt is unsuccessful, send
RERR to source
❍ Advantage: repair links with less overhead,
delay and packet loss
❍ Disadvantages: longer delay and greater packet
loss when unsuccessful
66. 4-66
AODV: Summary (1)
❒ Routes need not be included in packet
headers (DSR does it)
❒ Nodes maintain routing tables containing
entries only for routes that are in active
use
❒ At most one next-hop per destination
maintained at each node
❍ DSR may maintain several routes for a single destination
❒ Unused routes expire even if topology does
not change
67. 4-67
AODV: Summary (2)
❒ Reactive/On – demand
❒ Sequence numbers used for route
freshness and loop prevention
❒ Route discovery cycle
❒ Optimizations can be used to reduce
overhead and increase scalability