Performance Analysis of Proactive Reactive and Hybrid Routing Protocols Considering Link SNR Value Using Qualnet

Research Paper (postgraduate), 2014
8 Pages



Ad-hoc network is a concept in computer communications, which means that users wanting to communicate with each other from a temporary network, without any form of centralized administration. Each node participating in the network acts both as host and router and must therefore be willing to forward packets for other nodes. For this purpose, a routing protocol is needed. Routing protocols in MANET such as OLSR-INRIA, DSR and ZRP finds out the path between a given sources destination node pair without considering the reliability of the links in the selected path. Some links in MANET are unreliable due to interference from transmissions from adjacent links, ambient noise system noise, jamming signals from intruder nodes all of which results in low throughput, packet delivery ratio, high jitter and end-to-end delay. In our work, we use Signal-to-Noise Ratio (SNR) as a measure of the link reliability. We propose modified secure version of the of three protocols namely OLSR-INRIA, DSR & ZRP coined as SOLSR-INRIA , SDSR, & SZRP which takes into account the link SNR value as a measure of link reliability in addition to the other parameters as in the original method in the route discovery phase. QualNet network simulator have been extensively used to evaluate the performance of our modified secure routing protocol over two different network scenarios consisting of 52 and 72 mobile nodes respectively considering random waypoint (RWP) mobility model. The results indicate high throughput, high packet delivery ratio and low jitter and end-to-end delay in comparison to the original protocols which do not account for wireless links reliability.

Keywords­­­­­:- SOLSR-INRIA, SDSR, SZRP, SNR, RWP, Throughput, Packet Delivery Ratio, Jitter, Reliability, Network Topology, Qualnet.


A Mobile Ad-hoc Network (MANET) consists of a number of mobile battery powered energy constraint nodes communicating with each other in single or multiple hops over wireless links. They are temporary and infrastructure less without any central controller. Every node generates its own data traffic and cooperatively forwards others which are not in direct communication range of each other i.e. acts both as an end terminal and router. Due to the mobility and dynamic addition/deletion of nodes, topology changes frequently and on-demand routing protocols are required. MANETs should be capable of handling these topology changes through network reconfigurations. Routing protocols for MANET should be adaptive to the topology changes and be capable of discovering new routes when old routes becomes invalid due to such change. The number of nodes in MANET changes with time so the routing protocols should be scalable.

A mobile ad hoc network is a collection of wireless mobile nodes that are dynamically and arbitrarily located in such a manner that the interconnections between nodes are capable of changing on a continual basis. There are some unique characteristics of mobile ad hoc networks.


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Fig 1: Routing Protocol

- Table driven: Every node in the network maintains complete routing information about the network by periodically updating the routing table. Thus, when a node needs to send data packets, there is no delay for discovering the route throughout the network. This kind of routing protocols roughly works the same way as that of routing protocols for wired networks.
- Source initiated (or demand driven): In this type of routing, a node simply maintains routes to active destination that it needs to send data. The routes to active destinations will expire after some time of inactivity, during which the network is not being used.
- Hybrid: This type of routing protocols combines features of the above two categories. Nodes belonging to a particular geographical region or within a certain distance from a concerned node are said to be in the routing zone and use table driven routing protocol. Communication between nodes in different zones will rely on the on-demand or source-initiated protocols.

This type of protocols maintains fresh lists of destinations and their routes by periodically distributing routing tables throughout the network. The main disadvantages of such algorithms are:

- Respective amount of data for maintenance.
- Slow reaction on restructuring and failures.



The Optimized Link State Routing (OLSR) protocol was designed by the French National Institute for Research in Computer Science and Control (INRIA) for mobile ad-hoc networks. It is a proactive routing protocol that employs an efficient link state packet forwarding mechanism called multipoint relaying on its way to optimize pure link state routing protocol. There is a two way optimization. One by reducing the size of the control packets and other by reducing the number of links that are used for forwarding link state packets. The reduction in the size of the link state packets is made by declaring only a subset of the links in the link state updates which are assigned the responsibility of packet forwarding known as Multipoint Relays. Periodic link state updates are facilitated by the optimization done by multipoint relaying facilities. No control packet is generated on the event of a link break or addition of a new link by the link state update mechanism which achieves higher efficiency when operating in a highly dense network.

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2.2 DSR

The DSR implementation that came with the extension uses promiscuous mode (i.e. eavesdropping), which means that the protocol learns information from packets that it overhears. The question is how realistic this is in a real environment. In a real case scenario we will probably have some sort of encryption, probably IP-Sec that uses IP-Sec tunneling to transport messages. We have made some small change to DSR that makes it possible to turn the eavesdropping feature on and off. The parameters that are configurable for DSR are shown in These values are the values specified in the DSR draft and have not been changed. The no propagating timeout is the time a node waits for a reply for a no propagating search. A no propagating search is a request that first goes to the neighbors. If the neighbors do not answer in this specified amount of a tune, a new request that will be forwarded by the neighbors will be sent. The send buffer in the DSR can hold 64 packets and the packets are allowed to stay in the buffer for 30 seconds

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Table 1: Time Access Protocols


Abbildung in dieser Leseprobe nicht enthalten

Table 2: Characteristics of Routing Protocols


- The effects of node misbehavior.
- Modeling adhoc networks.

There might be cases that the protocols that we have discussed cannot help out. For instance what if there are some nodes that do not want to cooperate? Or some other problems related proximity to each other. Some might behave as malicious and etc. Recall that in ad hoc networks, there is mobility, dynamic situations. In this part, our concern is Routing system.

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Fig 2.1: Node Distribution


A node in the middle may keep the message and not forward to package. It can affect the overall performance of the system. There are three different nodes.

1. Well-behaving nodes: that works, forwards the packet.
2. Malicious nodes: the ones that inject false information into messages or remove them completely from the network (blackholes).It has been proven that if the number of selfish nodes increases the packet loss in the network increases linearly as well. Besides that, in case of AODV, if there are many selfish nodes in the network we need to incerase the number of control messages ( to keep the track of what is going on in the network , and reestablish route if a node does not forward the packet ) . It results in increase of routing overhead. Selfish nodes: the ones that receives the packet but do not forward it.


Most ad hoc routing algorithms assume only well-behaving nodes to support multi-hop operation of the network. However if something goes wrong in between, everything can be affected in a negative way.


The destination node unicasts the best route (the one received first) and caches the other routes for future use. A route cache is maintained at every node so that, whenever a node receives a route request and finds a route for the destination node in its own cache, it sends a RREP packet itself instead of broadcasting it further.

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Fig 3: DSR Route Discovery


The route maintenance phase is carried out whenever there is a broken link between two nodes. A broken link can be detected by a node by either passively monitoring in promiscuous mode or actively monitoring the link. As shown in Figure 3.3, when a link break (F-G) happens, a route error packet (RERR) is sent by the intermediate node back to the originating node. The source node re-initiates the route discovery procedure to find a new route to the destination. It also removes any route entries it may have in its cache to that destination node. DSR benefits from source routing since the intermediate nodes do not need to maintain up-to-date routing information in order to route the packets that they receive. There is also no need for any periodic routing advertisement messages.

Abbildung in dieser Leseprobe nicht enthaltenFig 4: ROUTE MAINTENANCE

Availability guarantees the survivability of the network services despite attacks. A Denial-of-Service (DoS) is a potential threat at any layer of an ad hoc network. On the media access control layer, an adversary could jam the physical communication channels. On the network layer disruption of the routing operation may result in a partition of the network, rendering certain nodes inaccessible. On higher levels, an attacker could bring down high-level services like key management service.

Confidentiality ensures that certain information be never disclosed to unauthorized entities. It is of paramount importance to strategic or tactical military communications. Routing information must also remain confidential in some cases, because the information might be valuable for enemies to locate their targets in a battlefield.

Integrity ensures that a message that is on the way to the destination is never corrupted. A message could be corrupted because of channel noise or because of malicious attacks on the network.

Authentication enables a node to ensure the identity of the peer node. Without authentication, an attacker could masquerade as a normal node, thus gaining access to sensitive information.

Non-repudiation ensures that the originator of a message cannot deny that it is the real originator. Non-repudiation is important for detection and isolation of compromised nodes.


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Performance Analysis of Proactive Reactive and Hybrid Routing Protocols Considering Link SNR Value Using Qualnet
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Kalaiselvi N. Joshi (Author)A. Sivasankari (Author)S. Sudarvizhi (Author), 2014, Performance Analysis of Proactive Reactive and Hybrid Routing Protocols Considering Link SNR Value Using Qualnet, Munich, GRIN Verlag,


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