Ccag gossip based reliable multicast protocol

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 01 | Jan-2014, Available @ http://www.ijret.org 305
CCAG: GOSSIP BASED RELIABLE MULTICAST PROTOCOL
Smita Kapse1
, Amita Meshram2
, Supriya Thombre3
, Nilima Jichkar4
, Itrat Fatema5
1
Assistant Professor, 2
Assistant Professor, Department of Computer Technology,
YCCE, Nagpur, Maharashtra, India
5
Assistant Professor, Department of Computer Technology, ACET, Nagpur, Maharashtra, India
Abstract
The essential requirement in MANET is now group communication or multicasting since it is used in applications such as network news
dissemination, collaborative computing, disaster relief operation, sensor network, military services. In this type of application reliability
plays an important role. Designing a reliable multicast protocol in MANET is challenging task due to the dynamic topology, limited
bandwidth, constraints of node capability, and frequent disconnections in MANET. In this paper, we propose a scheme called
Congestion Control Anonymous Gossip(CCAG) to improve the reliable packet delivery of multicast routing protocols and decrease the
variation in the number of packets received by the different nodes. It also consider the issues of reliability, low end to end delay, control
overhead and packet delivery in mobile ad-hoc networks. The propose scheme works in two phases. In the first phase any suitable
protocol is used to multicast the message to the group, while in second phase, the gossip protocol tries to recover lost messages.
Keywords: Ad-hoc Wireless network, Anonymous Gossip, MAODV, Packet delivery Reliability, Locality of gossip,
Congestion.
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1. INTRODUCTION
An adhoc network is a dynamically reconfigurable wireless
network without any fixed infrastructure. Such type of network
have several resource constraints like bandwidth, battery
power, and demands like latency and other types of QoS,
reliability and security etc. This type of network is specifically
useful in situations like military and disaster relief operation
etc. In such an application multicast is a natural requirement.
The transmission of packets to a group of zero or more hosts
identified by a single destination address is called multicasting
[16]. Large number of multicast protocols are available in
adhoc network like MAODV [5], ODMRP [14], MCEDAR [9]
etc. but this protocol does not provide reliability guarantees due
to
1 Mobility and congestion.
2 Transient partition.
3 Maintenance of multicast structure.
In a wired network the basic technique used for recovering the
lost messages are
1 Flooding
2 Gossip
In flooding any node that receives the packet retransmits to its
entire neighbor hence routing messages are propagated
unnecessary and hence congestion in the network increases.
Gossip [15][6] is a control form of flooding in this the messages
are slowly propagated without congesting the network.
Classical gossip technique used in wired network recovers lost
messages but it requires partial or full knowledge of other
group members.
Hence these methods are impractical in adhoc network due to
several constraints of adhoc network.
Hence we are implementing a protocol which makes use of
gossip technique called Congestion Control Anonymous
Gossip (CCAG) which provides
1 Reliability guarantees
2 Eliminates the variation in the number of packets
received by group member.
3 Less control overhead.
4 High packet delivery.
2. CONGESTION CONTROL ANONYMOUS
GOSSIP PROTOCOL
A gossip based reliable multicast protocol[4] involves two
phases as depicted in following figure
Fig-1: Use of Gossip with Existing Multicast protocol
In the first phase, any suitable unreliable protocol is used to

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multicast the message m, to be sent to the group. In this
experiment we are using the multicast adhoc on demand
distance vector routing protocol to disseminate the message
unreliably. In the second phase, gossip protocol is used to
recover lost messages from other members of the group that
might have received it. This phase consists of periodically
repeated gossip rounds in the background as more and more
messages are multicast. A single gossip round can potentially
recover many lost messages. A single round of gossip consists
of the following steps:
• Node A randomly chooses another member of the
group, say B.
• A sends B the information about messages it has
received or not received.
• B checks to see if it has received any of the messages
listed by A.
• Then A and B could exchange messages which are not
a part of each other’s message history.
To implement the CCAG protocol we include the concept of
following:
• Anonymous Gossip.
• Locality of Gossip.
• Cached Gossip.
• Pull mode of message exchange.
2.1 Anonymous Gossip
AG does not require any member to know the other members of
the multicast group. A new type of message called gossip
message [1][2] is used. This message has the following five
fields:
• Group Address: Address of the multicast group
• Source Address: Address of the node sending the
gossip message
• Lost Buffer: An array of fixed size, which carries
sequence numbers of messages that the source node
believes it has lost
• Number Lost: The size of the Lost Array
• Expected Sequence Number: The sequence number
of the next message that the source expects
Following Steps are used to implement Anonymous Gossip
• If all the packets are not receive successfully then
• Generate the gossip message.
• Pick a node at random
• Send a digest of local contents to the peer.
• Propagate the message among multicast tree.
• If group member then
accept and unicast gossip reply
Else
propagate gossip message to next node.
2.2 Locality of Gossip
Locality of gossip[3] refers to the gossip locally i.e. with nearer
member with a very high probability and with distant nodes
occasionally. Which results in low control overhead?
Following Steps are used to implement Locality of Gossip
• Maintain an additional nearest_member field in MRT
table of MAODV protocol.
• If gossip message is received then next hop with
smallest nearest member value is hosen with higher
probability than with greatest nearest member value.
• Validity of nearest_member is maintain byWhen new
member join send MACT message When existing
member leaves send Prune message
• Each node send the modify message along the route
2.3 Cached Gossip
Cached Gossip [16][2] uses the unicast routes to gossip with
those nodes whose membership is already known. The
inclusion of the algorithm adversely affect the delay recorded in
locating/delivering packets: whenever a node leaves the group;
a new node joins the group; or there is a need for
reconfiguration leading to topological changes.
Following Steps are used to implement Cached Gossip
• Every group member maintain member_cache
• Table consists of (node_add, num_hopes,
last_gossip).
• If (member_cache table full )then If (member with
greatest no. of hopes) delete it Else delete member
with most recent last_gossip
• member_cache table is updated with each gossip
reply, data packet or maintenance packet.
2.4 Pull Mode of Message Exchange
Because of the importance of the direction of information
exchange. The proposed protocol implements a pull mode of
message exchange.
Following Steps are used to implement Pull mode of message
exchange.
• Each group node maintains Lost_table and History
_table.
• Lost_table( sender_add, seq_no) entry is made when
• sequence no greater than expected seq. no is received.
• History_table contains most recent messages received
• If (receive gossip message) then compare Lost_table
with History _table If (message found) then unicast
gossip reply to initiator Else propagate gossip message
to next node
The following figure depicts the complete CCAG protocol

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Fig2: The Complete CCAG Protocol
3. SIMULATION
3.1 Implementation Environment
Operating System : Cent O.S.6.0 NS2 version :
ns-allinone-2.33 Gnu Plot : GNU4.2.5 Perl Script
3.2 Simulation Environment
The network N consists of |N| nodes with same transmission
and communication capabilities, communicating through
bidirectional wireless links between each other. A multicast
group G is a subset of N with nG nodes.
The following assumptions are made :
• Simulation area : 1800 * 900 meters
• Simulation duration: 100 sec.
• Physical/ MAC layer: IEEE 802.11 at 2 Mbps,
250m transmission range
• Mobility model : Random way point model with no
pause time.
• Every node has unique physical ID.
• The transmission radius for each node is fixed.
• Network consist of single multicast group.
• All the nodes join the group at the beginning of the
simulation and remains in it throughout the run period.
33 Performance Metrics
After executing the tcl script the trace file is generated this
contains a lot of information that may not be required to analyze
the performance of a protocol. We are interested in those
information that is sufficient to predict the efficiency of a
protocol. The following performance metrics are needed to be
consider to analyze and compare the performance of MAODV
and CCAG protocol.
• Packet delivery Ratio: It is the ratio of number of data
packets received by the destinations to the number of data
packets sent by the source
PDR% = (TRP / TSP) * 100
Where, PDR: Packet delivery Ratio TRP: Total Received
Packets TSP: Total Sent Packets
PDR is used to compare MAODV protocol with CCAG
protocol. As it describes the loss rate that is seen by the
protocol this in turn affects the maximum throughput that
the network can support. This metric characterizes both
completeness and correctness of the protocol.
• Congestion overhead: It gives the evaluation of the
efficiency of a routing protocol and so if this
parameter is low it means that less overhead is
introduced in the network and the result is network is
less congested and less collision and interference
occur.
It is the ratio of total number of routing signaling
packets transmitted during the simulation in terms of
total number of packets received.
CO = TRSP/ TXP
Where,
CO: Congestion overhead
TRSP: Total of Routing Signaling Packets TXP: Total
of transmitted Packets .
• Data packets received by each node: It is used to
calculate the variation in the number of packets
received by each node. In this we calculate the number
of data packets received by each node over a time
• End to end delay: End-to-end delay is considered as
the average time taken by a packet to reach an Node
from the time it leaves the sender. When a data packet
is first created by the source, it is tagged with a send
time. Subsequently, each node that receives the packet
calculates the end-to-end delay by subtracting the time
the packet was received with the initial send time.
3.4 Simulation Result and Analysis
Graphs are one of the ways to analyze and compare the result of
the trace file. To plot the graph in NS2.33 we are using the
software GNUPLOT which gives more appropriate scale. To
plot the graph we have to first extract the desired field from the
trace file. To do this we had written Perl script. The following
are the graphs showing the outputs of the two protocols
MAODV Vs CCAG. They show the performance metrics that
are discussed in the above section.

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Fig-3: Packet delivery Ratio
Fig- 4: Congestion overhead
Fig- 5: Data packets received by each node
Fig- 6: End to End Delay
CONCLUSIONS
Reliable Multicasting is an important requirement in the
MANET. Hence by considering this requirement we design and
implemented congestion control anonymous Gossip protocol
for Adhoc network which provides the reliability guarantees. It
uses MAODV protocol to dissipate the messages unreliably
and on top of that CCAG protocol is used. The performance
comparison between MAODV and CCAG using graph shows
that CCAG gives 22% improvement in the performance as
compare to MAODV protocol. The results show that CCAG
reduces congestion, increases Packet delivery ratio and also
reduces the variation in the number of packets received by
different group members.
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Ccag gossip based reliable multicast protocol

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