comparative analysis of resilience configurations for wdm ... · nodes, consumption of energy for...
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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,
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
669 Himanshi Saini and Amit Kumar Garg
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
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
670 Himanshi Saini and Amit Kumar Garg
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
Fig. 3: Scenario for Packets Traversing Path3
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
671 Himanshi Saini and Amit Kumar Garg
Fig. 4: Scenario for Packets Traversing Path4
Fig. 5: Scenario for Packets Traversing Path5
Fig. 6: Scenario for Packets Traversing Path6
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
672 Himanshi Saini and Amit Kumar Garg
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
International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
673 Himanshi Saini and Amit Kumar Garg
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.
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International Journal of Engineering Technology, Management and Applied Sciences
www.ijetmas.comMay 2017, Volume 5, Issue 5, ISSN 2349-4476
674 Himanshi Saini and Amit Kumar Garg
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