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					   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 2, Issue 5, September – October 2013                                    ISSN 2278-6856

      PTEA algorithm for Wireless P2P Networks in
           the presence of cooperative cache
                                        Karunakar Kothapelli#1, S Santhosh#2
                                               computer science and Engineering,
                                perusing in Sreenidhi institute of Science and Technology,
                                              Hyderabad, Andhra Pradesh, India.

                                               computer science and Engineering,
                                                 1Jawaharlal Nehru University
                             , Sree Chaitanya College of engineering,
                                              Karimnagar, Andhra Pradesh, India.
Abstract— Improving the performance of p2p networks              There have been many implementations of wireless ad
such as Ad Hoc networks and Mesh Networks is nontrivial.         hoc routing protocols. In [3], Royer and Perkins
Many algorithms proposed to improve the performance of Ad        suggested modifications to existing kernel code to
Hoc networks in the presence of cooperative cache.        We     implement AODV. In [10], the authors explored several
propose a novel dynamic algorithm to improve asymmetric          system issues regarding the design and implementation of
cooperative cache, where the data requests are transmitted to    routing protocols for ad hoc networks. Dynamic Source
the cache layer on every node, but the data replies are only
                                                                 routing (DSR) [4] implemented by Monarch project in
transmitted to the cache layer at the intermediate nodes that
need to cache the data. Novel algorithm ‘PTEA’ Which
                                                                 FreeBSD. This implementation was entirely in the kernel
Efficiently calculates the Optimized path between nodes in       and made extensive modification in the kernel IP packet.
network and determines the optimized node to Cache the           However none of them looked into bandwidth utilization
data.                                                            and route discovery in the presence of cooperative cache.
                                                                 Security is extremely important for the deployment of a
Keywords— Ad Hoc Networking, Cooperative Caching,                Mobile Ad-hoc Networks (MANET) due to its openness
PTEA.                                                            to attackers, the absence of an infrastructure, and the lack
                                                                 of centralized administration. Most research efforts have
1. INTRODUCTION                                                  been focused on secure routing protocols [7]. Secure auto
Ad Hoc network is an autonomous system of mobile hosts           configuration and public-key distribution [1], namely the
connected by wireless links, the union of which forms a          SAPKD scheme in this paper. It guarantees the
communication network modelled in the form an                    uniqueness of IP address allocation. At the same time, it
arbitrary communication graph. A                MANNET           distributes the public key of the new node to all (or most)
environment is characterised by energy-limited nodes,            members in the MANET. In the ideal situation, all the
bandwidth-constrained, variable-capacity wireless links          nodes will receive the binding of the public key and IP
and dynamic topology, leading to frequent and                    address from the new node.
unpredictable connectivity changes. The main aim of our          Although cooperative caching has been implemented by
work is to reduce the overhead of node calculation as they       many researchers [5], [9], these implementations are in
are energy-limited and Bandwidth Constrained.                    the web environment, and all these implementations are
If the nodes in the networks are able to cooperative with        at the system level. As a result, none of them deals with
each to cache and share the data then power can be saved         on-demand nature of the ad hoc routing protocols. To
and bandwidth can be utilized properly. For example, in a        realize the benefit of cooperative cache [2], intermediate
battlefield, a wireless P2P network may consist of several       nodes along the path need to check every passing by
commanding officers and a group of soldiers. Each officer        packet to see if the cached data match the data request.
has a relatively powerful data center, and the soldiers          We study the traffic and utilization of band width between
need to access the data centers to get various data such as      the nodes in the presence of cooperative cache. Since in
the detailed geographic information, enemy information,          the     MANNET environment Nodes are free to move
and new commands. The neighbouring soldiers tend to              arbitrarily with different speeds; thus, the network
have similar missions and thus share common interests. If        topology may change randomly and at unpredictable
one soldier has accessed a data item from the data center,       times. So it is effective to have alternative pats from
it is quite possible that nearby soldiers access the same        source to destination. When a data request comes to the
data some time later. Cooperative Caching has                    data center then the data center selects the optimized
implemented in [2],[6],[8],[11] which allow sharing and          route to the source and finds the optimized node along the
coordination of cached data among multiple nodes. But            path to cache the data to server further requests.
these [2], [6], [8], [11] did not specify the efficient
bandwidth utilization.

Volume 2, Issue 5 September – October 2013                                                                        Page 215
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 2, Issue 5, September – October 2013                                    ISSN 2278-6856

In this section, first we present the basic idea of three
cooperative caching schemes proposed in [2], [11]:
CachePath, CacheData and asymmetric cooperative
caching approach [2]. Then we present our PTEA
algorithm.                                                                  Figure 2 Request Data Flow
A. Cooperative caching schemes                                Since the data replies are no need to pass through the
Fig. 1 illustrates the Cache Path concept. Suppose node       cache layer of every node. If no intermediate node needs
N1 requests a data item (D1) from N0. When N3                 to cache the data, N1 sends the requested data item D1
forwards D1 to N4, N5 knows that N1 has a copy of the         directly to the N0 without going to cache layer of every
data. Later, if N2 requests D1, N3 knows that the data        node. If intermediate node needs to cache the data then
source N0 is four hops away whereas N1 is only two hops       data server determines those caching nodes and sends
away. Thus, N3 forwards the request to N1 instead of N4.      requested data to caching nodes.
Many routing algorithms such as AODV [3] and DSR [4]
provide the hop count information between the source and
destination. Caching the data path for each data item
reduces bandwidth and power consumption because nodes
can obtain the data using fewer hops.
In the CachePath, a node need to record the path
information of all passing by packets rather, it only
records the data path when it is closer to the caching node
than the data source. If N0 forwards D1 to the destination                   Figure 3 Reply Data Flow.
node N1 along the path N5—N4—N3, N4 and N5 wont
cache D1 path information because they are closer to the
                                                              3. PTEA ALGORITHM
data source than the data center.
                                                              Our work is to implement the Path Traffic Estimation
In CacheData, the intermediate node caches the data
                                                              Algorithm PTEA at the data center, which calculates the
when it finds that the data item is frequently accessed.
                                                              network traffic and in the routes between the nodes. And
For example, in fig.1, if both N6 and N7 request D1
                                                              calculates the availability of bandwidth based on these
through N5, N5 may think that D1 is popular and cache it
                                                              two factors (Traffic and Bandwidth). Through these, the
                                                              data center calculates the optimal intermediate nodes to
                                                              cache the data.
                                                              The algorithm has four steps
                                                              STEP 1: Forwarding the Request Packet. After a request
                                                              message is generated by the node it adds the destination
                                                              address Dest_addr, Data_id and next hop address so that
                                                              data request can reach the destination. This can be
                                                              accomplished by AODV or DSR routing algorithms.
           Figure 1 A Wireless P2P Network.                   When intermediate node receives the data request it
                                                              delivers to the cache layer, the cache manager checks
Design of cooperative cache must be layered design and        whether requested data item available in local cache or
the cache layer should reside in the user space to avoid      not if available it serves else forwards to next neighbour
the kernel implementation. Asymmetric cooperative             by changing the address and next hop by increasing the
cache approach, in this the data requests and data replies    hop count. The node increases the request count if the no
are treated differently to reduce the time delay. For         of request for a same data is requested.
example, in fig. 1 if node N0 request a data item D1 from     STEP 2: Calculating the best route. The center will takes
N1 then the request packet has to passed down to the          the hop count, no of requests for the same data item and
cache layer of every node. The cache layer of every node      availability of band width from the routing table and
checks whether the requested data item available in its       request packet count then calculate the best route and the
local cache or not. If the requested data item is available   best node to cache the data and best node to cache the
then it serves the request otherwise it simply forwards the   path along the discovered route. Here PTEA algorithm
request to its neighbour via the path N0—N5—N4---             calculates the free slots in the links available from data
N3—N1. Now the data center N1 calculates the                  center to requesting node based on the available links the
optimized node (CachedData) between N1 to N0 to cache         data center selects that path to send the requested data
the requested data to serve further and sends requested       item.
data item to cache layer of CachedData nodes.

Volume 2, Issue 5 September – October 2013                                                                   Page 216
   International Journal of Emerging Trends & Technology in Computer Science (IJETTCS)
       Web Site: Email:,
Volume 2, Issue 5, September – October 2013                                    ISSN 2278-6856

STEP 3: Determining the CacheData node. After a               4. CONCLUSION
request message reach to the data center, it determines the   In this paper we present a novel PTEA algorithm for
optimized node to cache the data. While determining           wireless P2P networks in the presence of cooperative
CachedData node it checks for no of requests for the same     cache which will finds the best place to cache the data
data item, no of links from that node to another node and     and the alternative routes to transfer the data from data
the bandwidth and free slots along the link. The data         center to the requesting node. The data center will
center counts the no of requests for the same data which      effectively finds all optimized nodes to cache data for
is available in the Req_count, path information and free      future and sends the data to those intermediate
slots from above second step then determines the              CachingNodes in effective manner using the concept of
CacheData node. After determining the CacheData node          bandwidth utilisation of the network.
it finds CachePath node along the path.
STEP 4: Data Reply. The data center sends the requested       ACKNOWLEDGMENT
data to the intermediate nodes which are selected to cache    The work presented in this paper is supported by many
the data along the path discovered by data center. So the     authors so we would like to thank all the authors for their
CacheData node saves the data in its local cache for          innovative work.
future use and forwards the data to requester. If the
CachePath node encounters the message then it saves the       REFERENCES
path information of Cache Node.
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                Figure 5 PTEA Algorithm.

Volume 2, Issue 5 September – October 2013                                                                    Page 217

Description: International Journal of Emerging Trends & Technology in Computer Science (IJETTCS) Web Site: Email:, Volume 2, Issue 5, September – October 2013 ISSN 2278-6856, Impact Factor 2.524 ISRA:JIF