Comparative Analysis of Resilience Configurations for WDM ... · nodes, consumption of energy for transmitting, receiving, idle power, sleep power. NAM file is a visual graphical

International Journal of Engineering Technology, Management and Applied Sciences

www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476

668 Himanshi Saini and Amit Kumar Garg

Comparative Analysis of Resilience Configurations for WDM

Test Network

Himanshi Saini*, and Amit Kumar Garg**

Assistant Professor*, Professor**

Electronics and Communication Engineering Department,

DCRUST, Murthal, Sonepat, Haryana, India.

Abstract: Network survivability requires maintaining a balance between network speed and network reliability.

Survivable networks can quickly and efficiently recover from failures. It is imperative to design networks that meet the

application requirements in terms of delay, throughput before any failure or after any network component failure.

Survivability techniques reserve some capacity within the network and during failure time it automatically re-route

traffic using this reserved capacity. To improve overall communication capacity, it is important for a network to keep

functioning optimally with or without failures. In this paper, survivability of network is being examined. A test network of

21 nodes is simulated in which packets are forwarded from source to destination. Dynamic routing is used, which proves

to be a backbone for survivability. As when failure occurs on one link, dynamic routing forwards packets safely through

other path. Possible alternate paths of a working path in test network are examined. Various parameters of possible

alternate paths are calculated and compared. This analysis is performed on Network Simulator version 2.

Keywords- Survivability, Protection, Restoration, Capacity Utilization.

I. INTRODUCTION

Survivability refers to capability of a network to continue performing even after occurrence of any failure. An

interruption or failure of high speed optical network operating at Gbits/s or higher, even for fraction of

seconds results in significant loss of information. Failures in an optical network can be categorized depending

on whether it damages links or switching devices. In the first situation, faults often results from external

causes in which cable cuts are very frequent. Equipment failures in the network nodes are mainly due to

internal causes such as hardware degradation or management software inefficiency [1]. Link failure is most

common type of failure in optical network. Equipment failures are less common but they cause great loss to

network Often the focus lies on the consideration of link failures solely, which are caused by fiber cuts [2].

Channel failures are also one of failures in WDM networks which occur due to the failure of equipment

operating on that channel at transmitting end or receiving end.

The survivability in optical networks can be classified into two categories as pre-planned protection and

dynamic restoration. Pre-planned protection means that recovery from network failures is based on preplanned

schemes, which relies on resources (fibers, wavelengths, switches, etc.) dedicated to protection purposes. In

pre-planned protection, some resources are reserved for recovery from failures at either connection setup or

network design time, and are kept idle even when there is no failure. This shows that the use of capacity is not

very efficient, but through this, the level and speed of recovery from a failure can be guaranteed. [3].Dynamic

restoration implies the discovery of spare capacity dynamically in the network to restore the affected services,

that is, the resources used for recovery are not reserved at the time of connection establishment/set up, but are

chosen from available resources such as fibers, wavelengths, switches, and so on when the failure occurs. This

is more efficient than predesigned protection from the context of resource utilization. In dynamic restoration,

the restoration time is longer, recovery of failure cannot be guaranteed because sufficient spare capacity may

not be available at the time of failure [4].

The protection to a network can be through two ways: link protection and path protection. Path based

survivability is more efficient in capacity utilization compared to link based survivability, since it only needs

spare capacity for the whole reserved path instead of every link along the path [5]. In link based survivability,




restoration time is faster than path based survivability since path mechanism requires a longer time to generate

a fault notification message. In link based survivability, all alternative paths are already reserved when the

working path is computed. When a link fails, the end node pairs of the failed link are immediately switched to

the reserved path[6].

A test network is considered in which dynamic routing is configured for resilience. All possible backup paths

are examined for a working path. Throughput, Delay and Jitter for these paths are compared and analyzed to

select the path best suited for an application.

II. SIMULATION MODEL

Simulation are performed on network simulator version 2, which is an event driven simulation tool and works

on a linux platform that is useful in studying the dynamic nature of communication networks. NS2 provides

users with a way of specifying such network protocols and simulating their corresponding behaviors. NS-2

was built in C++ and provides the simulation interface through OTcl, an object-oriented dialect of Tcl. The

user describes a network topology by writing OTcl scripts, and then the main NS program simulates that

topology with specified parameters. General format trace files, NAM format trace files, personalized trace

files are examples of NS2 output files[6]. NS2 provides the designer with information about network

performance through network performance metrics like packets send, received and dropped, initial energy of

nodes, consumption of energy for transmitting, receiving, idle power, sleep power. NAM file is a visual

graphical window which illustrates the node movements, range, and packet transfer including time [7].

The schematic of network under test is shown in fig 1. Simulation Parameters are shown in table 1.

Fig. 1: Schematic for network under test (Packets Traversing Path1)

Table 1: Simulation Parameters

Parameter Value/Option

Bandwidth 20 Mbps

Delay 2ms

Packet Size 1 Kbytes

Traffic CBR

Routing Technique Distance Vector

Simulation Time 0.6 sec




On simulating the network the path taken by the network is (1-18-20-10), this the shortest path through which

packets travel from source to destination as shown in fig 1. Possible backup paths as shown in table 2, for this

working path are examined. Packets traversing the considered backup path 2, path 3, path 4, path 5 and path 6

are shown in Figure 2, 3, 4, 5 and 6 respectively. The performance metrics such as average delay, average

jitter and average throughput of all the paths are calculated and compared using AWK script.

Table 2: Working and Backup paths

PATH Path route

1 (Working Path) 1-18-20-10

2 1-17-12-11-10

3 1-0-15-16-12-11-10

4 1-0-14-13-12-11-10

5 1-2-3-4-19-20-10

6 1-2-3-4-5-6-7-8-9-10

Fig. 2: Scenario for Packets Traversing Path2











III. RESULTS and DISCUSSION

Failure is restored in the network by providing backup paths and the results are compared through various

performance metrics by calculating average delay, average throughput and average jitter. Table 3 shows the

values of average delay, throughput and jitter for working path as well as possible backup paths.

Table 3: Average Delay, Average Throughput, and Average Jitter for Path 1-6

PATH AVERAGE

DELAY (ms)

AVERAGE

THROUGHPUT

(kbps)

AVERAGE

JITTER (ms)

PATH1(1-18-20-10) 2.6265 1280.73 0.144783

PATH2(1-17-12-11-10) 2.7750 1566.16 0.221936

PATH3(1-0-15-16-12-11-

10)

3.1562 2065.10 0.309679

PATH4(1-0-14-13-12-11-

10)

3.1005 2078.94 0.294643

PATH5(1-2-3-4-19-20-10) 3.0264 2099.70 0.319886

PATH6(1-2-3-4-5-6-7-8-9-

10)

3.3368 2896.21 0.449442

It is seen that path1 has least average delay, least throughput and least jitter. Path 2 has least jitter and least

delay among all backup paths. Path 6 has highest throughput among all backup paths.

Figure 7 shows the throughput vs. time plot for all the paths. Path 3, 4 and 5 have almost same throughput.

Path1 has least throughput and path 6 has maximum throughput. Figure 8 shows delay vs. packet ID plot for

all the paths. Paths 3, 4 and 5 have almost same delay. Path1 has minimum delay and path 6 has maximum

delay.

Fig 7: Throughput vs. Time plot for all considered paths




Fig 8: Delay vs. PacketID for all considered paths.

IV. CONCLUSION

Wavelength-division multiplexing (WDM) technology has increased the capacity of optical fiber network and

has enabled bidirectional communication over one strand of fiber. These networks meet the ever increasing

demand of bandwidth by provide low error rates, low delay and high transparency [8]. Survivability is one of

the important component of WDM network design due to high data carrying capacity of WDM optical

network.In this paper, a test network of 21 nodes is being analyzed through Network Simulator version 2, in

which packets or information flows from source to destination. Possible resilience paths for a working path

are examined.These resilience paths are observed after incorporating dynamic routing in the test network.

Various parameters like Average Delay, Average Throughput and Average Jitter of different paths are

calculated and compared. It is observed that out of possible paths between source and destination, path 6 has

highest throughput and highest delay. Paths 3, 4 and 5 offer almost same numbers for Average Delay,

Average Throughput and Average Jitter. Path 1 which is the working path has least delay and least

throughput. Out of resilience paths path 2 has least delay and least throughput. According to the application

requirements we can select any of the paths which meet the requirements of the desired application.

REFERENCES 1. Guido Maier, AchillePattavina, Simone De Patre , Mario Martinelli , “Optical Network Survivability:Protection

Techniques in the WDM Layer”, Photonic Network Communications, Vol 4, Issue 3- 4, 2002, pp. 251-269.

2. Darli A. A. Mello, Dominic A. Schupket, Matthias Scheffel andHelio Waldman, “Availability maps for connections

in WDM optical networks”, 5th international workshop on Design of Reliable Communication Networks, 2005, pp.

77-84.




3. Dongyun Zhou, Suresh Subramaniam, “Survivability in Optical Networks”, IEEE Network, vol. 14, no. 6, pp. 16–

23, Dec2000.

4. BayremTriki, Slim Rekhis, and NoureddineBoudriga, “Survivable Routing in All Optical Networks,” ICTON, 2011.

5. J. Doucette and W. D. Grover, “Comparison of mesh protection and restoration schemes and the dependency on

graph connectivity," in International Workshop on Design of Reliable Communication Networks, 2001, pp. 121-128.

6. TeerawatIssariyakul,Ekram Hossain, “ Introduction to Network Simulator NS2”, ISBN: 978-0-387-71759-3 e-

ISBN: 978-0-387-71760-9, Springer, 2009.

7. RachnaChaudhary, ShwetaSethi, Rita Keshari, SakshiGoel, “A study of comparison of Network Simulator -3 and

Network Simulator -2”, International Journal of Computer Science and Information Technologies, Vol. 3 (1) , 2012,

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8. https://www.slideshare.net/saur_1991/wdm-15774191 accessed on 18 May, 2017

https://www.slideshare.net/saur_1991/wdm-15774191

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Comparative Analysis of Resilience Configurations for WDM ... · nodes, consumption of energy for transmitting, receiving, idle power, sleep power. NAM file is a visual graphical