efficient shortest path routing (espr) algorithm for multicasting in

Efficient Shortest Path Routing (ESPR) Algorithm for Multicasting in

Wireless Mesh Network

1Geetanjali Rathee, 2Ninni Singh, 3Hemraj Saini 1, 2, 3 Department of Computer Science and Engineering

1, 2, 3 Jaypee University of Information Technology, Waknaghat-173234 INDIA

[email protected],[email protected], [email protected]

Abstract

Today’s fast and mobility oriented era of

communication the networking infrastructure

requires efficient communication. SPT and MCT

are the two standard algorithms to provide efficient

communication in wireless networking. SPT

provides communication by recognizing the

shortest path in a tree and propel the packet

throughout this path. Since failures exist in the

network, the SPT algorithm resists the failure by

sending an ICMP messages which increases

congestion ratio and rerouting of the packets while

MCT algorithm forwards the packets on the basis

of least number of transmissions. As the MCT

algorithm transmits by consuming less number of

cost, but during failure of intermediate links, it is

also having the scope of improvement in the

efficiency, i.e. transmission cost, rerouting cost and

complexity of the network. These drawbacks are

overcome by the proposed algorithm which works

efficiently during failure of intermediate links. NS-2

is used to simulate the results and shown the results

with comparative analysis of three algorithms

Keywords: WMN, SPT, MCT, Congestion,

ESPR.

1. Introduction In wired computer network, as the number of users

increase in the network, there will be a demand of

some novel technologies that can oversee the issues

like mobility and as a result wireless computer

network is developed. In wireless network, wired

connection is not needed and because of this

feature, there is an exponential growth of users for

Internet access. As we all know communication in

wireless network runs for substantial purpose,

Wireless Mesh Network (WMN) become a

promising concept to solve the challenges in

today’s scenario in cost effective aspects to the

service provided by adopting three features i.e.

self-structuring, flexibility and self-management [1,

2].

WMN [3], as shown in figure-1, is made up of two

types of nodes, first, wireless mess client and

second, wireless mesh router. The wireless mesh

router has routing capability and not having any

resources like- memory and power constraints

while wireless mesh clients has resources like-

memory and power constraints but not having any

routing capability. Mesh router has less mobility so

it is mostly viewed as a stationary node. The mesh

router which connects the other mesh routers and

clients to the backbone or Internet is called a mesh

gateway. Mesh gateway is also practiced to connect

any two mesh networks [3].

Fig. 1. Wireless Mesh Network

Multicast Routing [5, 9] is a type of

communication where information is delivered to a

set of destination nodes simultaneously as shown in

figure-2. In this, the delivery of messages is

managed at each layer only once. The duplication

of messages is provided only at branch layer where

links are differentiated to the destination node.

Even though Multicast Routing is applied in

different applications like- teleconferencing, video

conferencing and email sending, researchers on

Multicast Routing in WMN is still in its early days.

Shortest Path tree (SPT) [6] and Minimum Cost

Trees (MCT) are the two underlying approaches of

multicast routing.

The aim of SPT algorithm is to create a tree such

that the distance between source and destination

should be minimal. The most commonly used SPT

algorithms are Dijkstra [7] and Bellman- ford [8].

Fig. 2. Multicast Routing

Hemraj Saini et al, Int.J.Computer Technology & Applications,Vol 6 (1),111-115

IJCTA | Jan-Feb 2015 Available [email protected]

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ISSN:2229-6093

The goal of MCT is to downplay the overall cost of

the tree. On comparing both trees SPT and MCT,

the end to end cost of SPT is lower than that of

MCT. The distance between source and

destinations is maximum in case of MCT that

means the average path length of SPT is lower than

MCT. The complexity of MCT is more than the

SPT. Due to its higher complexity rate, the majority

of routing protocols is based on SPT i.e. distance

vector multicast routing (DVMR) [11], Multicast

Open Shortest Path First (MOSPF) [12]. Rest of the

work is presented in four sections. In section-II,

recent proposed approaches, i.e. SPT [11] and

MCT [6] have discussed with their drawbacks. In

section-III, the proposed approach has provided

with failure cases. The comparative analysis of

three approaches will be done in section-IV.

Finally, the section-V concluded the work.

2. Related Work In this section, the computation cost of SPT and

MCT have been compared. This comparative study

evaluates the drawback of both algorithms during

communicating the data in the network. For this

study, the WMN [4], as shown in figure-3 have

deemed.

.

Fig. 3. Shortest Path Tree

The network consists of a source node S, two

destination node D1, D2 and four forwarding nodes.

Firstly the SPT [11] has calculated and then the

MCT [6].

SPT algorithm, forwards the packet by

constructing a shortest path tree to the destination

node. Let us consider a source node S which wants

to transmit a packet to a destination node D1 and

D2. As shown in figure-3, source node S will

transmit the packet to D1 and D2 by choosing S-C-

E-B-D1 and S-C-E-B-D2 paths, therefore, the cost

of packet transmission from S to D1 is 4 (1+1+1+1)

and from S to D2 is 4 (1+1+1+1) and the overall

cost for transmitting the packet from source S to D1

and D2 is 5(S-C-E-B -D1and B-D2).

Now, another multicast routing algorithm MCT

has been considered for the computation. Instead of

considering the cost, it sends the packet on the

basis of least number of transmissions. The

working of MCT is shown by considering figure-4.

Let again source node S wants to transmit a packet

to multiple destinations D1 and D2. The MCT

evaluates the transmission of the entire network

and sends the packet by choosing the path having

less number of transmissions. By showing in

Figure-4, MCT choose S-A-B-D1 and S-C-E-D2,

so, the cost of transmission from S-D1 is 3(2+2+1)

and from S-D2 is 3(1+1+3). The overall cost of

packet transmission from S-D1 and S-D2 is 10.

Fig. 4. Minimum Cost Tree

The drawback of MCT is its complexity.

Furthermore, in the case of failure [10], both the

algorithms utilize the ICMP message protocol,

which increases the computing power, cost,

rerouting transmission and congestion ratio. Thus,

to overcome all such challenges the proposed

algorithm is provided in section-III, which work in

an efficient manner.

3. Proposed Approach In the previous section, some of the disadvantages

associated with both SPT and MCT algorithms are

identified. To overcome above mentioned

drawbacks we have suggested an algorithm

efficient shortest path routing (ESPR). As shown in

table-1.

Table-1 shows if a node Ni wants to send the

packets to destination node Di and Dj, initially node

Ni will check for the failure case using through an

ack (acknowledgement).

If ack is received within RTT then there is no

failure in the network and node Ni will send the

packet to destination Di and Dj using SPT

algorithm. In other case if ack is not received

within RTT that means failure exist in the network

and the previous node Ni-1 will choose the next

shortest path from the Routing table and send to the

destination nodes Di and Dj.

Fig. 5. When node C-D fails



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Table 1. ESPR Algorithm

Terminologies used:

S= source node

Di and Dj= two destination nodes

Ni= current node

Ni-1= previous node

N= Network

RTT= Round Trip Time

1. Select a node Ni from a network N.

2. if ( an ack receives within RTT)

Then

No failure exists

Node Ni sends the packet using SPT

algorithm

3. else

node Ni-1 chooses next another path

Ni-1 send the packet to destination Di, Dj

The proposal utilizes the concept of SPT i.e. source

node S transmits the packet by choosing the

shortest path to the destination node, but in case of

failure instead of sending an ICMP message to the

source Node S, the failure detected node will

choose another shortest path (by considering its

routing table) that leads to destination node D1 and

D2 and starts transmitting the packet through that

path. The failure case is shown in the figure-5.

In normal cases (when no failure exist inside the

network), ESPR works same as SPT i.e. Source

node S sends the packets to the destination node D1

and D2 through S-C-E-B-D1 and S-C-E-B-D2, while

during failure, i.e. if link C-E fails, as node C is not

able to get an acknowledgement within its (Round

Trip Time) RTT, it will immediately choose

another path to send the packets to the destination

node D1 and D2 through S-C-B-D1 and S-C-B-D2

path. The corresponding flowchart of our algorithm

is shown in figure-6.

Fig. 6. Flow chart of ESPR

4. Performance Evaluation So far we have discussed our proposed algorithm

with both previous approaches and shown how the

proposed algorithm works in the failure cases. In

this section we have simulate our work in NS-2

simulator on different network sizes and shown the

corresponding graphs of SPT, MCT and ESPR in

terms of throughput, resiliency.

5 10 15 20 25 305

10

15

20

No. of Nodes

Thro

ughput/

ResilencyS

PT

Throughput

Resilency

Fig.7. Throughput and resiliency of SPT

Furthermore we have construct a table of all three

algorithms using two parameters i.e. throughput (in

term of cost) and resiliency (against node failure).

The above graphs and table clearly shows that PA

works efficiently in failure cases as compare to

SPT and MCT. Finally we conclude our paper in

table 3 by showing the features, pros and cons of

SPT, MCT and PA.

5 10 15 20 25 307

8

9

10

11

12

13

14

15

16

17

No. of Nodes

Thro

ughput/

ResilencyM

CT

Throughput

Resilency

Fig. 8. Throughput and resiliency of MCT



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5 10 15 20 25 304

4.5

5

5.5

6

6.5

7

7.5

8

8.5

9

No. of Nodes

Thro

ughput/

ResilencyE

SP

R

Throughput

Resilency

Fig. 9. Throughput and resiliency of ESPR

5 10 15 20 25 304

6

8

10

12

14

16

No. of Nodes

Thro

ughput

(in t

erm

s o

f cost)

SPT

MCT

ESPR

Fig. 10. Comparative throughputs of SPT,

MCT and PA.

5 10 15 20 25 305

10

15

20

No. of Nodes

Resilency (

in t

erm

s o

f link f

ailure

)

SPT

MCT

ESPR

Fig. 11. Comparative resiliencies of SPT,

MCT and ESPR

Table 3. Pros and cons of SPT, MCT and

ESPR

SPT MCT PA

Task: SPT finds

the

shortest

path in a

network.

MCT is

generally

used to find

path having

least

transmission

nodes.

It works

same as

SPT, but it

works

efficiently

in the case

of a node or

link failure.

Pros: Minimize

end to end

delay.

The Overall

cost of the

multicast tree

reduces.

1)

Minimizes

no. of

computation

2) Minimize

congestion

ratio.

3) Minimize

rerouting.

Cons: 1) Use

ICMP

message

in the case

of failure.

2)

Increases

congestion

1) Increases

the

computational

complexity.

2) Increases

congestion

because of

rerouting.

---

Table 2. Throughput and resiliency of SPT,

MCT and ESPR

Parameter

Metric

Approaches 7-

node

15-

node

30-

node

Throughput

(In terms of

cost)

Shortest Path

Tree

5 7 10

Minimum

Cost Tree

6 10 12

PA 4 5 7

Resiliency

(Against

node

failure)

Shortest Path

Tree

8 12 19

Minimum

Cost Tree

7 9 14

PA 5 7 9

5. Conclusion and Future Work

In this work an ESPR multicast algorithm has

proposed which ensures efficient transmission in

WMN during failure. The task was simulated in

NS2 at different network sizes and found that cost

of transmission is less as compared to other

algorithms i.e. SPT and MCT. The proposal has

introduced several advantages over SPT and MCT

i.e. minimizes numbers of computations,

congestion ratio and re-routing of packets. Further

to achieve more precise results of ESPR algorithm,

it will be analyzed in the physical environment and

the results will be revised for other doable

measures.



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References [1.] I. F Akyildiz, X .Wang and W. Wang, “A Survey on

Wireless Mesh Networks”, IEEE Radio

Communications, 47(4):445-487, 2005. [2.] H. Saini, “1-2 Skip List Approach for Efficient

Security Checks in Wireless Mesh Networks”,

International Journal of Electronics and

Information Engineering, 1(1):9-15, 2014. [3.] L .Zhou, and Z. Haas, “Securing adhoc

networks”, IEEE Network Magazine, 13:24-

30:1999.

[4.] Raffaele Bruno, M. Conti, and E. Gregori, “Mesh networks: commodity multihop ad hoc

networks”, Communications Magazine,

IEEE, 43(3):123-131, 2005.

[5.] S.Paul, “Multicast on the Internet and Its Applications”, Kluwer Academic Publishers, 1998.

[6.] G. Zeng, B.Wang, Y. Ding, L. Xiao, and M. Mutka,

“Efficient Multicast Algorithms for Multichannel

Wireless Mesh Networks”, IEEE Trans. Parallel Distrib. Syst., 21(1):86-99, 2010.

[7.] L. Ping, and B. Cuimei, “A Improvement of the

Shortest Path Based on the Dijkstra Algorithm [J]”,

Qinghai Normal University, 1(1):79-80, 2008. [8.] W. Zhang, H. Chen, C. Jiang, and L. Zhu,

“Improvement and Experimental Evaluation

Bellman-Ford Algorithm”, International

Conference on Advanced Information and Communication Technology for Education

(ICAICTE 2013), 150-153, 2013.

[9.] J. Sobczak, and P. Zwierzykowski, “Multicast Routing in Wireless Mesh Networks”, In the

proceedings of The Eighth Advanced International

Conference on Telecommunications, 62-68, 2012.

[10.] G. Rathee, A. Mundra, N. Rakesh, and S.P. Ghrera, “Buffered Based Routing and Resiliency Approach

for WMN”, Published in IEEE International

Conference of Human Computer Interaction,

Chennai, India, 1-7, 2013. [11.] B.A Fourozan, “TCP/IP Protocol Suite”, 3rd

Edition, Singapore, McGrawHill, 2004.

[12.] P.G. Ranjitkar, I. M. Suliman, P. Geil, Kuipers and

R. Prasad, “IP multicast implementation based on the multicast extensions to OSPF protocol”

Personal Wireless Communications, IEEE

International Conference on, 484 – 489, 2000.



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