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Mobile Ad-hoc Network (MANET) is definitely an attractive technology which has enticed a lot of research endeavours within the last years. Even though the theory of wireless, structure-less, dynamic networks is attractive, there are still several main imperfections which avoid industrial growth. Security is just one of these primary obstacles; MANETs is known as specifically at risk of security strike. One solution offered to improve security strength is by using multipath routing algorithms. Nevertheless multipath routing also presents new issues when it comes to security and security overhead. In this paper we look at the difficulty of protected routing and expose the Trust Route Spatially Disjoint Paths (TRSDMP) routing protocol .TRSDMP selects one of the most The larger trust levels for that node through spatially disjoint routes . The outcomes reveal that TRSDMP raises the network throughput and minimizes each the quantity of discovery overhead and also end-to-end delay.
Wireless networks have a lot of attention these years; this is due to the increases in its usage and applications, such as mobile phones, laptops or personal digital assistances (PDAs). Infrastructure-less wireless networks or MANETs one of the Wireless networks category that does not consist of a Base Station (BS) to connect a wired Local Area Network (LAN), so in MANET each node has the responsibility to manage the route each in its range.
Routing is a fundamental issue of networks. One of these challenges that create the propose of mobile ad hoc network routing protocols a complicated task. The lack of infrastructures in wireless network makes it vulnerable to many types of attacks (Mavropodi and Douligeris, 2006), Because the most difficult to secure due to the fact that transmission medium is open to anyone within the geographical range of a transmitter.
There are specific types of attack that can appear in MANET's such as: Denial of service attacks aim at the complete disruption of the routing function and therefore the whole operation of the ad hoc network. (Argyroudis and O'Mahony, 2004), and Lack of cooperation attacks that happens when the node does not provide its services to other nodes to save its own resources like, computation power and energy (Berton et al, 2006).
While encryption of wireless traffic can be achieved, it is usually at the expense of increased cost and decreased performance. Many routing protocols have been proposed to solve the security problems emerged in MANET.
The rest of the paper is structured as follows. In section 2 we review related work. Section 3 explains the TRSDMP protocol. Section 4 shows and analysis protocol performance based on simulations with Glomosim simulation. Finally, in Section 5 we summarize our conclusions and discuss some future work.
2. LITERATURE REVIEW
Many researches have focused on multipath routing protocols Multipath on-demand routing protocols try to discover multiple paths at both the traffic sources and at intermediate nodes in a single route discovery attempt, and provide a secure path for multipath routing protocols .
In this section we will provide a related work of the Multipath Routing in MANET's and Secure Routing Protocols for MANET's .
2.1 Multipath Routing in MANET's
Multipath routing protocols try to discover multiple paths at both the traffic sources and at intermediate nodes in a single route discovery attempt. Multipath routing also provides a higher bandwidth and effective load balancing since the load of data forwarding can be distributed over the existing paths (Meghanathan, 2007). Also the multiple paths are utilized as a backup or auxiliary method in most of multipath routing protocols (Wu and Harms, 2001).
The Ad Hoc On-demand Distance Vector Routing (AODV) protocol is a reactive routing protocol that maintains information when routes needed only. And builds a single loop free path to each other node on the network, only one path is saved although extra packets are sufficient to construct more than one path. On the other hand, Ad hoc On-demand Multipath Distance Vector Routing (AOMDV) is a multipath extension of AODV that computes multiple loop-free link-disjoint routes. Each node has a routing table keeps routing information for the destination. Periodic hello messages are used to detect and monitor links to neighbours and to update the routing table. (Marina and Das, 2001).
When a traffic source needs a route to a destination in AOMDV, it starts the route discovery process. A route discovery process initiated by flooding Route Request (RREQ) packet across the network and waiting for a Route Reply (RREP) message. Any intermediate node receiving a RREQ sets up a reverse path to the source, and if it has a valid route to the destination it will generate a RREP, otherwise it will rebroadcast the RREQ packet. As the destination node receives a RREQ, it also generates a RREP. The generated RREP will be sent directly to the source using the reverse path.
Modification of the ad-hoc On-Demand Multipath Distance Victor routing protocol (AOMDV) to discover a set of node-disjoint paths, which are spatially separated this modification introduce new protocol called Maximally spatially Disjoint Multipath Routing Protocol (MSDMP). MSDMP design is based on AOMDV , When a traffic source needs a route to a specific destination, it starts the route discovery process. The route discovery process is initiated by flooding a RREQ packet across the network and waiting for a RREP (Almobaideen et al, 2008).
The MSDMP modifies the AOMDV RREQ message to include the list of nodes participating in the path between a specific source and destination. The list of paths included in the RREQ message helps in deciding whether a specific route satisfies the disjointness property or not. The new RREQ message of MSDMP show new filed added to the RREQ message is the Route List field, which stores the addresses of the nodes that are participating in the path.
2.2 Secure Routing Protocols for MANET's
Since security is an essential issue in ad hoc networks, many secure routing protocols have been proposed to mention the security challenges and issues related to routing in ad hoc network.
In (Han et al, 2006), Multipath Security Aware Routing (MP-SAR) is suggested as an improvement of the existed Security Aware Routing (SAR) protocol. MP-SAR keeps data confidentially offered by SAR and increases performance of data transmission speed.
The existence of multiple paths between nodes in an ad hoc network introduce a solution for securing data transmission. The new solution which focuses on data security transmitting aspects is called Secured Data based Multipath routing protocol (SDMP). This protocol uses the advantage of the fact that even if an attacker succeeds to have one or lots of transmitted parts, the probability of original message reconstruction is low (Bouam and Benothman, 2003).
In (Talipov et al, 2006), the authors propose a path hopping method based on R-AODV (Kim et al, 2006). Path Hopping Reverse AODV (PHR-AODV) provides an analytic method to expect intrusion rate. In addition, the authors present a path hopping routing mechanism to build complete or partial node-disjoint multipath depending on the network topology.
Secure Ad hoc On-demand Distance Vector (SAODV) is an offer for security extension to the AODV protocol (Zapata and Asokan, 2002). In SAODV, every route discovery that is initiated by a node corresponds to a new one-way hash chain.
TRSDMP is proposed as modification of both protocol MSDMP and AOMDV. TRSDMP chooses the most spatially disjoint paths, which could join partially via nodes that specify a certain security threshold. Using TRSDMP, choosing parted disjoint paths that are more secure, could be better than choosing other maximally spatially disjoint paths that are less secure.
TRSDMP insert in RREQ message the trust level of the node participated in the route path, and the route list in the AOMDV RREQ message .Figure 3.3 shows the new RREQ message used in TRSDMP. The Trust-Level List carries the trust value of each node participated in the Route-List.
Figure 3.1: TRSDMP RREQ Message Format.
In TRSDMP adjust the maximally node disjoint algorithm to make the path become partially disjoint via nodes that specify a certain trust threshold. When an intermediate node checks the disjointness of a certain path and there is a common node in this path, a check of trust level of this common node is made. If the trust level of the common node exceeds a certain threshold value, this path will be considered in the selection process of multipath.
Through TRSDMP the trust value must be added to the Trust-Level List in the RREQ packet. Any node checks the disjointness of the path and before generating a RREP packet on a specific path it must check the Trust level of all the nodes participating in the path. If the path has a node with trust value less than a certain trust threshold this path will not be used and the RREQ will be discarded.
4. RESULTS AND ANALYSIS
In this paper the Global Mobile Information System Simulation Library network simulator (GloMoSim) was used to evaluate the performance of the TRSDMP.
In the experiments we have conducted in this paper the simulation modelled a network of 100 mobile hosts located at random in a 2000X2000 meters area. We used Distributed Coordination Function (DCF) of IEEE 802.11 for wireless LANs as the MAC layer protocol. In the scenarios of experimentation, the mobile nodes have been moving randomly for 400 seconds simulation time. Each node moves independently according to the random waypoint mobility model with a 25 (Meter/Second) as maximum mobility speed and 25 S as pause time.
We use the following performance metrics to compare the performance of TRSDMP and MSDMP protocols: Network Throughput, Average end-to-end Delay, Packet delivered successfully from the sources to the destinations,and Routing Overhead .
To show the enhancement obtained by TRSDMP regarding the selected performance metrics and parameters we present the improvement ratio to help in the comparison between TRSDMP and S-MSDMP. Enhancement Ratio (IR) of both protocols can be computed according to Formula 1.
ER = ( T - MS) / T â€¦.........................................â€¦......................................... (1)
Where T: value of TRSDMP
MS: value of MSDMP.
4.3 Results and Analysis
In this section, we present the results and their analysis of the TRSDMP protocol regarding the mentioned performance parameters and metrics. We compare the results of the proposed TRSDMP with MSDMP.
4.3.1 Traffic Load
Increasing the number of packets the traffic source has to send ranging from 20,40,60,80 to 100 packets to change the traffic load of the network. Figure 4.1 compares between the average end-to-end delay of TRSDMPand MSDMP while changing the traffic load.
Figure 4.1: Average End-to-End delay Vs. Number of Packets.E:\Ø¨Ø³Ù… ØÙ„Ù„Ù‡ ØÙ„Ø±ØÙ…Ù† ØÙ„Ø±ØÙŠÙ…\MY PAPER\chpter 4\4.1.png
TRSDMPchooses the set of multipath with less number of constraints than in S-MSDMP that make a reduction in delay . This in turn reduces the delay needed by the source to discover a new path if the existing path becomes invalid or broken. According to this experiment, the improvement ratio of delay reduction gained by TRSDMP is 19%.
In Figure 4.2, the discovery overhead of the two protocols as the traffic load increases. TRSDMPhas lower discovery overhead than S-MSDMP and this is because by using TRSDMPthere is a greater number of the discovered paths than with S-MSDMP. The improvement ratio of discovery overhead reduction gained by TRSDMPin this experiment is 4%. E:\Ø¨Ø³Ù… ØÙ„Ù„Ù‡ ØÙ„Ø±ØÙ…Ù† ØÙ„Ø±ØÙŠÙ…\MY PAPER\chpter 4\4.2.png
Figure 4.2: Discovery Overhead Vs. Number of Packets.
The comparison of throughput for the two protocols that shown in figure 4.3. The improvement ratio of throughput gained by TRSDMPis 3%. The throughput of both TRSDMPand S-MSDMP decreases as the traffic load increases and this happen due to the fact that when the traffic load increases, nodes in the network will be overloaded which oblige them to drop packets.
Figure 4.3: Throughput vs. Number of Packets.
4.3.2 Varying Node Density
Node density is considered as the performance parameter in the evaluation of the two protocols, In order to change the density of nodes in the simulated terrain a gradual increment of the terrain area was done in order to move to a sparser mode. The successive experimental scenarios assume a terrain with a side length ranging 500 to 2500 meters. In Figure 4.4, compare the end-to-end delay of TRSDMPand S-MSDMP while changing the node density expressed by using the length of the terrain side. In contrast with S-MSDMP, TRSDMPchooses partially disjoint paths based on trust level of the nodes. Choosing partially disjoint paths increases the number of selected multipath and as a result decreases the delay resulting from the extra time needed to discover a new path when the existed path becomes broken or invalid. The improvement ratio of delay reduction gained by TRSDMP in this experiment is 10%.
Figure 4.4: Average End-to-End Delay vs. Terrain Dimension.
In Figure 4.6, present a comparison of throughput between TRSDMPand S-MSDMP as the density of node decreases. We can notice from the figure that TRSDMPgains higher throughput than S-MSDMP as the nodes become sparser with an improvement ratio of 3%.
4.3.3 Number of Maximum Allowed Path
Increasing the maximum allowed number of multiple paths that can be stored in a source to a specific destination. We started from two paths since we are interested in multipath routing. The number of paths increased to six paths. In figure 4.5. We can notice from the figure that TRSDMP incurs less end-to-end delay than MSDMP with an improvement ratio of 4.5 %. This is because in contrast with MSDMP, TRSDMPchooses not only the maximally spatially disjoint multipath, but also the paths that could join partially at trusted node. Choosing multipath based on these criteria increases the number of selected paths which could be used to send data packet. Sending packets over a greater number of paths reduces the average end-to-end delay in case of path breakage.
Figure 4.5: Average End-to-End Delay vs. Maximum Number of Allowed PathE:\Ø¨Ø³Ù… ØÙ„Ù„Ù‡ ØÙ„Ø±ØÙ…Ù† ØÙ„Ø±ØÙŠÙ…\MY PAPER\chpter 4\4.8.png
The effect of increasing the maximum number of allowed path on the throughput is shown in Figure 4.6. One can notice from the figure that TRSDMPgives the greatest throughput difference with maximum number of allowed path equals three. It is clear that TRSDMPobtains higher throughput than S-MDMP as the number of maximally allowed path increased with an improvement ratio of 3.2%. TRSDMPchooses a greater number of paths to send data packet which reduces the delay and as a result increases the throughput.E:\Ø¨Ø³Ù… ØÙ„Ù„Ù‡ ØÙ„Ø±ØÙ…Ù† ØÙ„Ø±ØÙŠÙ…\MY PAPER\chpter 4\4.10.png
Figure 4.6: Throughput vs. Maximum Number of Allowed Path
5. CONCLUSIONS AND FUTURE WORKS
In this paper we have proposed the TRSDMP routing protocol. Chooses the most spatially disjoint paths which could join partially trusted level via nodes that specify a certain security threshold. TRSDMP exploits a trusted node to participate in the selected set of route between a source and destination.
The simulation results have shown that the TRSDMP obtain higher throughput than MSDMP under different network conditions. In addition TRSDMP incurs less average end-to-end delay and discovery overhead than that of S-MSDMP.
As future work, we propose to compute the trust level of each node based on the properties of the set of discovering multipath and statistical information about how each of these paths behaves on the network.
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