This document provides a review of routing protocols in Mobile Ad Hoc Networks (MANETs), highlighting their dynamic topology and challenges such as link failures and energy management. Various routing strategies, categorized as reactive, proactive, or hybrid, are discussed along with examples of protocols like DSDV, DSR, and AODV. The paper emphasizes the need for efficient routing mechanisms to accommodate the variable network conditions inherent in MANETs.

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© I A E M E
A REVIEW ON ROUTING PROTOCOL IN MANET
Parvinder1 Dr. V.K. Suman2
1Research Scholar, Shri Venkateshwara University, U.P.
2Professor Dean, IIMT-IET, Meerut.
ABSTRACT
Mobile ad hoc networks (MANET) are characterized by multi-hop wireless links and
resource constrained nodes. One of the major challenges in mobile ad hoc networks (MANETs) is
link failures due to mobility. Because nodes in a MANET act as routers for any ongoing packet
communication and have limited transmission ranges, the communication links are broken, and
packet losses occur. To improve network lifetime, energy balance is an important concern in such
networks. This paper concentrates on routing techniques which is the most challenging issue due to
the dynamic topology of ad hoc networks. There are different strategies proposed for efficient
routing which claimed to provide improved performance. There are different routing protocols
proposed for MANETs which makes it quite difficult to determine which protocol is suitable for
different network conditions .This paper provides an overview of different routing protocols.
Keywords: MANET, Routing Protocols, Reactive, proactive, Hybrid.
I. INTRODUCTION
In the next generation of wireless communication systems, there is a tremendous need for the
rapid deployment of independent mobile users. Significant examples include emergency
search/rescue missions, disaster relief efforts, mine site operations, battlefield military operations,
electronic classrooms, conferences, convention centers, etc. [1]. A network of such users is referred
to as Mobile Ad hoc Network (MANET). Such a network does not have any fixed infrastructure (i.e.,
no base stations/ routers); nodes arbitrarily change their positions resulting in a highly dynamic
topology [1] causing wireless links to be broken and re-established on the-fly.
An ad-hoc network, as the name suggests, is a network formed by nodes connected arbitrarily
for some temporary time. They provide a powerful paradigm for modeling open self configuring
wireless networks and seem so appropriate to use in the fourth generation of mobile networks.
Obviously, a convergence of all these technologies with 3G/4G [2] mobile networks will probably

2. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 5, July – August (2013), © IAEME
lead to various integrated solutions. A Mobile Ad-hoc network (MANET) is consists of mobile
routers connected wirelessly to each other where each node is free to move. This results in a
continuously changing topology. Some examples of the possible uses of ad hoc networking include
business associates sharing information during a meeting, soldiers relaying information for
situational awareness on the battlefield and emergency disaster relief personnel coordinating efforts
after a hurricane or earthquake [2].
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The MANET [3] is a collection of nodes, which have the possibility to connect on a wireless
medium and form an arbitrary and dynamic network with wireless links. This means that links
between the nodes can change with time, new nodes can join the network, and other nodes can leave
it. The wireless network can be classified into two types:
Infrastructured or Infrastructure less [4]. A MANET is expected to be of larger size than the
radio range of the wireless antennas, because of this fact it could be necessary to route the traffic
through a multi-hop path to give two nodes the ability to communicate. There are neither fixed
routers nor fixed locations for the routers as in cellular networks - also known as infrastructure
networks. This type of network can be shown as in figure 1.
Figure 1: Wireless Network Structures (Infrastructure Networks) [3]
Cellular networks consist of a wired backbone, which connects the base-stations. The mobile
nodes can only communicate over a one-hop wireless link to the base-station; multi-hop wireless
links are not possible. By contrast, a MANET has no permanent infrastructure at all. All mobile
nodes act as mobile routers [3].
In Infrastructureless or Ad Hoc wireless network, the mobile node can move while
communicating, there are no fixed base stations and all the nodes in the network act as routers. The
mobile nodes in the Ad Hoc network dynamically establish routing among themselves to form their
own network ‘on the fly’. This type of network can be shown as in figure 2 [4].
Figure 2: Wireless Network Structures (Infrastructure less Networks)[3]

3. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
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II. ROUTING IN MANETS
A Mobile Ad Hoc Network or spontaneous network is an infrastructureless, self-organized
and multi-hop network with rapidly changing topology causing the wireless links to be broken and
re-established on-the-fly. A key issue is the necessity that the Routing Protocol must be able to
respond rapidly to the topological changes in the network.
In these networks, each node must be capable of acting as a router. As a result of limited
bandwidth of nodes, the source and destination may have to communicate via intermediate nodes [5].
Major problems in routing are Asymmetric links, Routing Overhead, Interference, and Dynamic
Topology.
A routing protocol is needed whenever a packet needs to be transmitted to a destination via
number of nodes and numerous routing protocols have been proposed for such kind of ad hoc
networks. These protocols find a route for packet delivery and deliver the packet to the correct
destination. The studies on various aspects of routing protocols have been an active area of research
for many years. Many protocols have been suggested keeping applications and type of network in
view [4].
Many researches find that every protocol identified also fit into the core categories of;
reactive, proactive or hybrid routing protocols in additional to any other characteristics they exhibit
[6].
Cost benefits trade-off between proactive and reactive protocols [15]
• Advantage: proactive Vs reactive
Proactive protocols: Routes are readily available when there is any requirement to send packet to
any other mobile node in the network. Quick response to Application program.
Reactive protocols: These are bandwidth efficient protocols. Routes are discovered on demand
basis. Less Network communication overhead is required in this protocol.
• Disadvantage: proactive Vs reactive
Proactive protocols: These maintain the complete network graph in current state, where it is not
required to send packets to all those nodes. Consumes lots of network resources to maintain up-to-date
status of network graph. “A frequent system-wide broadcast limits the size of ad-hoc network
that can effectively use DSDV because the control message overhead grows as O (n2).” [15].
1. Table-driven or Proactive Protocols: Proactive routing protocols attempt to maintain
consistent, up-to-date routing information between every pair of nodes in the network by
propagating, proactively, route updates at fixed intervals. Representative proactive protocols
include: Destination-Sequenced Distance- Vector (DSDV) routing, Clustered Gateway Switch
Routing (CGSR), Wireless Routing Protocol (WRP), Optimized Link State Routing
(OLSR)and The Fisheye State Routing (FSR)[7].
2. On-demand or Reactive Protocols: A different approach from table-driven routing is
reactive or on- demand routing. Reactive protocols, unlike table-driven ones, establish a route
to a destination when there is a demand for it, usually initiated by the source node through
discovery process within the network. Reactive protocols, unlike table-driven ones, establish a
route to a destination when there is a demand for it, usually initiated by the source node
through discovery process within the network. Representative reactive routing protocols

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include: Dynamic Source Routing (DSR), Ad hoc On Demand Distance Vector (AODV)
routing, Temporally Ordered Routing Algorithm (TORA) and Associativity Based Routing
(ABR).
3. Hybrid Routing Protocols: Purely proactive or purely reactive protocols perform well in a
limited region of network setting. However, the diverse applications of ad hoc networks across
a wide range of operational conditions and network configuration pose a challenge for a single
protocol to operate efficiently. Researcher’s advocate that the issue of efficient operation over a
wide range of conditions can be addressed best match these operational conditions [7].
Representative hybrid routing protocols include like as Zone Routing Protocol (ZRP) and
Zone-based Hierarchal Link state routing protocol (ZHLS).
III. VARIOUS ROUTING PROTOCOLS
a. Destination Sequenced Distance Vector (DSDV)
The proactive DSDV protocol was proposed by [8] and is based upon the Bellman-Ford
algorithm to calculate the shortest number of hops to the destination . Each DSDV node maintains a
routing table which stores; destinations, next hop addresses and number of hops as well as sequence
numbers; routing table updates are sent periodically as incremental dumps limited to a size of 1
packet containing only new information [6]. DSDV compensates for mobility using sequence
numbers and routing table updates, if a route update with a higher sequence number is received it
will replace the existing route thereby reducing the chance of routing loops, when a major topology
change is detected a full routing table dump will be performed, this can add significant overhead to
the network in dynamic scenarios.
b. OLSR
Clausen and Jacquet proposed the Optimized Link State Protocol, a point-to-point proactive
protocol that employs an efficient link state packet forwarding mechanism called multipoint relaying
[5]. It optimizes the pure link state routing protocol. Optimizations are done in two ways: by
reducing the size of the control packets and by reducing the number of links used for forwarding the
link state packets. Here each node maintains the topology information about the network by
periodically exchanging link-state messages among the other nodes. OLSR is based on the following
three mechanisms: neighbor sensing, efficient flooding and computation of an optimal route using
the shortest-path algorithm. Neighbor sensing is the detection of changes in the neighborhood of
node. Each node determines an optimal route to every known destination using this topology
information and stores this information in a routing table. The shortest path algorithm is then applied
for computing the optimal path. Routes to every destination are immediately available when data
transmission begins and remain valid for a specific period of time till the information is expired [5].
c. Dynamic source routing (DSR)
It uses the concept of source routing in which the creates routes only when source requires
[9]. It is based on link state algorithm. As it is on demand routing protocol, the routing overhead is
less. This Protocol is composed of two essential parts of route discovery and route maintenance.
Route Discovery: When a source node S wants to send a packet to the destination D, it first checks
its route cache. If there is an entry for the destination node, then the source uses the available route in
cache. If route not found or the the route cache has an expired route, then it initiate the route
discovery process. Route cache contains the recently discovered routes. Route discovery requires 7
fields during this process such as sourceid, destid, ReqID, Addresslist, Hoplimit, NetworkInterf---
aceList, Acknowledgment list. Then source node broadcasts the message to its neighbour. Moreover,

5. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 5, July – August (2013), © IAEME
source node also maintains a replica of messages sent in its send buffer. Packets can be dropped if
send buffer is full or the time limit for route discovery is over. When a nodes destination or the
intermediate node having route to destination receives the route request message, it generates route
reply [9] Route Maintenance: Route maintenance includes monitoring the routes against failure
through route error messages and route cache [10].
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Figure 3: Propagation of Route Request (RREQ) packet Route Reply (RREP) packet.[11]
There is no need of keeping routing table in DSR [4] protocol. Route cache can further
decrease route discovery overhead. DSR reduces overhead of route maintenance. However DSR is
not scalable to large networks and packet Size grows with length of the route due to source routing.
d. Ad Hoc On-demand Distance Vector (AODV)
The AODV [13] routing protocol is an “on demand” routing protocol, which means that
routes are established when they are required. This routing protocol is based on transmitting Route
Reply (RREP) packets back to the source node and routing data packets to their destination. Used
algorithm consists of two steps: route discovery and route maintenance. Route discovery process
begins when one of the nodes wants to send packets. That node sends Route Request (RREQ)
packets to its neighbors. Neighbors return RREP packets if they have a corresponding route to
destination. However, if they don’t have a corresponding route, they forward RREQ packets to their
neighbors, except the origin node. Also, they use these packets to build reverse paths to the source
node. This process occurs until a route as been found [12].
Figure 4: AODV Working[16]
Routing tables which only have information about the next hop and destination are used for
routing information maintenance. When a route link disconnects, for example, a mobile node is out
of range, neighbor nodes will notice the absence of this link. If so, neighbor nodes will check
whether there is any route in their routing tables which uses a broken link. If it exists, all sources that
send traffic over the broken link will be informed with Route Error (RRER) packet. A source node
will generate a new RREQ packet, if there is still a need for packet transmission [12].

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e. WRP
The Wireless Routing Protocol, as proposed by Murthy and Garcia-Luna-Aceves [5, 14], is a
table-based protocol similar to DSDV that inherits the properties of Bellman- Ford Algorithm. The
main goal is maintaining routing information among all nodes in the network regarding the shortest
distance to every destination. Wireless routing protocols (WRP) is a loop free routing protocol. WRP
is a path-finding algorithm with the exception of avoiding the count-to-infinity problem by forcing
each node to perform consistency checks of predecessor information reported by all its neighbors.
Each node in the network uses a set of four tables to maintain more accurate information: Distance
table (DT), Routing table (RT), Link-cost table (LCT), Message retransmission list (MRL) table. In
case of link failure between two nodes, the nodes send update messages to their neighbors. WRP
belongs to the class of path-finding algorithms with an important exception. It counters the count-to-infinity
problem by forcing each node to perform consistency checks of predecessor information
reported by all its neighbors. This eliminates looping situations and enables faster route convergence
when a link failure occurs [5].
f. Cluster-head Gateway Switch Routing (CGSR)
Cluster-head Gateway Switch Routing (CGSR) Protocol is a hierarchical protocol based upon
the DSDV Routing algorithm using a cluster head to manage a group of action nodes. The algorithm
works in a very simple manner. Then which in turn transmits it to the gateway of the destination
cluster. The destination cluster-head transmits it to the destination node. There are numerous
optimized cluster-head election mechanisms. On receiving a packet, a node finds the nearest cluster-head
along the route to the destination according to the cluster member table and the routing table.
Then the node consults its routing table to find the next hop in order to reach the cluster-head
selected in step one and transmits the packet to that node. The node consults its routing table to find
the next hop in order to reach the cluster-head selected in step one and transmits the packet to that
node [7].
g. DYMO overview
The DYMO routing protocol enables reactive, multi-hop routing between participating nodes
that wish to communicate [17]. It is a newly proposed protocol currently defined in an IETF Internet-
Draft. DYMO is a successor of Ad hoc On-demand Distance Vector (AODV) routing protocol. It is a
simplified combination of the AODV and Dynamic Source Routing protocol (DSR) routing
protocols. As is the case with all reactive ad hoc routing protocols, DYMO consists of two
operations: route discovery and route maintenance. Route discovery operation finds path between
source and destination and route maintenance operation generate error packet for finding another
path when active path is broken. Broadcasting is used to flood the network with the route request. If
the destination is discovered, a reply message containing the discovered path is sent back. A routing
table with information about nodes is maintained by each node[17].
IV. CONCLUSION
A Mobile Ad hoc networks (MANETs) are self organized wireless networks which are able
to connect on a wireless medium without the use of a infrastructure or any centralized administration.
Due to the absence of infrastructure, nodes may move frequently and the topology may change
dynamically. The mobile nodes perform both as a host and a router forwarding packets to other
nodes. Routing in these networks is highly complex. Due to moving nodes, many routing protocols
have been developed. Performance of each protocol is depending on their working in different
conditions. In this paper, we have presented and discussed the taxonomy of routing protocols in

7. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 5, July – August (2013), © IAEME
mobile ad hoc networks and provided comparisons between them. The protocols are divided into
three main categories: (i) source-initiated (reactive or on-demand), (ii) table-driven (pro-active), (iii)
hybrid protocol. For each of these classes, we reviewed and compared several representative
protocols. While there are still many challenges facing Mobile ad hoc networks related to routing and
security. Each routing protocol has unique features. Based on network environments, we have to
choose the suitable routing protocol.
[1] Abusalah, L., Khokhar, A., Guizani, M. (2008). A survey of secure mobile ad hoc routing
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REFERENCES
protocols. Communications Surveys Tutorials, IEEE, 10(4), 78-93.
[2] Sachan, G., Sharma, D. K., Tyagi, K., Prasad, A. (2013). Enhanced Energy Aware
Geographic Routing Protocol in MANET: A Review.
[3] Patel, C., Pandya, V. N., Shah, M. Survey of Reactive Routing Protocols for MANET.
In Proceeding of International Conference on Information Communication Embedded
Systems (ICICES 2014).
[4] Taneja, S., Kush, A. (2010). A Survey of routing protocols in mobile ad hoc
networks. International Journal of Innovation, Management and Technology,1(3), 2010-0248.
[5] Gupta, A. K., Sadawarti, H., Verma, A. K. (2011). Review of various Routing Protocols for
MANETs. proceedings of International Journal of Information and Electronics
Engineering, 1(3).
[6] Alex Hinds, Michael Ngulube , (2013) A Review of Routing Protocols for Mobile Ad-Hoc
NETworks (MANET). International Journal of Information and Education Technology, Vol. 3,
No. 1, February 2013
[7] Ipsita Panda A Survey on Routing Protocols of MANETs by Using QoS Metrics, International
Journal of Advanced Research in Computer Science and Software Engineering, Volume 2,
Issue 10, October 2012 ISSN: 2277 128X
[8] Perkins, C. E., Bhagwat, P. (1994, October). Highly dynamic destination-sequenced
distance-vector routing (DSDV) for mobile computers. In ACM SIGCOMM Computer
Communication Review (Vol. 24, No. 4, pp. 234-244). ACM.
[9] Kumar, Anit., (2013) A Comparative Study of AODV DSR Routing Protocols in Mobile
Ad-Hoc Networks, International Journal of Advanced Research in Computer Science and
Software Engineering, Volume 3, Issue 5, May 2013 ISSN: 2277 128X
[10] Kumar, D. D. S. (2010). Review: Swarm Intelligent based routing Protocols for Mobile Adhoc
Networks. International Journal of Engineering Science and Technology, 2(12), 7225-7233.
[11] Gupta, A. K., Kaur, J., Kaur, S. (2011). Comparison Of Dymo, Aodv, Dsr And Dsdv Manet
Routing Protocols Over Varying Traffic.International Journal of Research in Engineering
Applied Science, 1(2), 71-83
[12] Barakovic, S., Kasapovic, S., Barakovic, J. (2010). Comparison of MANET routing
protocols in different traffic and mobility models. Telfor Journal, 2(1), 8-12.
[13] Perkins, C. E., Royer, E. M. (1999, February). Ad-hoc on-demand distance vector routing.
In Mobile Computing Systems and Applications, 1999. Proceedings. WMCSA'99. Second IEEE
Workshop on (pp. 90-100). IEEE.
[14] Murthy, S., Garcia-Luna-Aceves, J. J. (1996). An efficient routing protocol for wireless
networks. Mobile Networks and Applications, 1(2), 183-197..
[15] Shrivastava, A., Shanmogavel, A. R., Mistry, A., Chander, N., Patlolla, P., Yadlapalli, V.
(2005). Overview of Routing Protocols in MANET’s and Enhancements in Reactive
Protocols. Department of Computer Science Lamar University.

8. International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN
0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 5, July – August (2013), © IAEME
[16] Dhenakaran ,Dr.S.S., (2013) An Overview of Routing Protocols in Mobile Ad-Hoc Network,
250
International Journal of Advanced Research in Computer Science and Software Engineering,
Volume 3, Issue 2, February 2013 ISSN: 2277 128X .
[17] Sharma, A., Joshi, R. D. (2013). Delay Reduction Technique for Dynamic MANET On-demand
Routing Protocol. parameters, 2(6).
[18] L.Malathi and Dr.R.K.Gnanamurthy, “A Novel Cluster Based Routing Protocol with Lifetime
Maximizing Clustering Algorithm”, International Journal of Computer Engineering
Technology (IJCET), Volume 3, Issue 2, 2012, pp. 256 - 264, ISSN Print: 0976 – 6367,
ISSN Online: 0976 – 6375.
[19] Thaker Minesh, S B Sharma and Yogesh Kosta, “A Survey: Variants of Energy Constrained
Reactive Routing Protocols of Mobile Ad Hoc Networks”, International Journal of Electronics
and Communication Engineering Technology (IJECET), Volume 3, Issue 2, 2012,
pp. 248 - 257, ISSN Print: 0976- 6464, ISSN Online: 0976 –6472.
[20] Archana Chougule and Dr.Vijay Wadhai, “Performance Analysis of MANET Routing Protocol
in Presence of Hybrid Traffic”, International Journal of Computer Engineering Technology
(IJCET), Volume 1, Issue 2, 2010, pp. 160 - 165, ISSN Print: 0976 – 6367, ISSN Online:
0976 – 6375.
[21] R.Rajasree and Dr.G.Kalivarathan, “A Review on Routing Protocols and Non Uniformity with
Wireless Sensor Networks”, International Journal of Computer Engineering Technology
(IJCET), Volume 3, Issue 3, 2012, pp. 348 - 354, ISSN Print: 0976 – 6367, ISSN Online:
0976 – 6375.