Performance Analysis of Delay in Optical Packet Switching Using Various Traffic Patterns

Document Sample
Performance Analysis of Delay in Optical Packet Switching Using Various Traffic Patterns Powered By Docstoc
					                                                           (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                     Vol. 8, No. 6, 2010

  Performance Analysis of Delay in Optical Packet
     Switching Using Various Traffic Patterns
A.Kavitha/Chettinad College of Engineering &                              P.Anandhakumar/Madras Institute of Technology,
                Technology                                                                       IT Dept
                      IT dept                                                           Chennai, Tamilnadu, India
  Chettinad College of Engineering & Technology,
             Karur, Tamilnadu, India

V.Rajamni/Indra Ganesan College of Engineering,
      Indra Ganesan College of Engineering
            Trichy, Tamilnadu, India

  Abstract— Quality of Service parameters are improved                  and there is no virtually any loss, but less utilization of
  for development of optical packet switching technology.               wavelength in this technique. In OBS, data is sent in bursts
  Delay is an important parameter in optical packet                     and a burst control message is sent ahead of each data burst
  switching networks and it affects the performance of the              to reserve a wavelength at each hop based on the expected
  network. In this paper, a mathematical model is presented             arrival time of the data burst. In OPS, messages are
  to evaluate the delay rate. Delay rates are analyzed for              transmitted in packets. At each switching node, the packet
  fixed packet length and variable length packet for various            head is processed in the electrical domain for routing
  traffic patterns viz. Non-uniform, Poisson and ON-OFF                 purpose and the packet data is kept in the optical domain.
  traffic models for various service classes using                      Wavelengths can be efficiently used in OPS [1]. Thus the
  Reservation Bit technique. The results are compared with              optical packet switching has emerged as one of the most
  the existing port based First-Fit wavelength assignment               promising technologies for future telecommunication
  algorithm. Here delay rates are reduced by 29% in our                 networks. OPS utilize very high bandwidth in the optical
  class based model than the port based model.                          fiber using WDM. WDM offers an aggregate throughput of
  Keywords-component; Optical Packet Switching (OPS),                   the order of terabits per second. WDM is widely becoming
  RB (Reservation Bit algorithm), FF (First-Fit Wavelength              accepted as a technology for meeting growing bandwidth
  assignment algorithm), Quality of Service (QoS), Packet               demands, and WDM systems are beginning to be deployed
  Loss Rate (PLR), BER (Bit Error Rate), WDM                            in both terrestrial and undersea communication links. Thus,
  (Wavelength Division Multiplexing).                                   WDM offers an excellent platform for carrying IP traffic.
                                                                        Consequently, OPS technology has many advantages, attract
                         I Introduction                                 more intensive attention than ever. The next generation
                                                                        telecom infrastructure definitely comprise of optical
   Due to the explosive growth of internet applications in              networks with improved QoS.
recent years, data traffic has been exceeded the telephony              In order to improve the performance of QoS in optical
traffic and bandwidth demands have been continuously                    packet switching network, a detailed study has been made in
increasing. It is also expected of the future networks to               this paper. The performance analysis of optical packet
transport heterogeneous traffic services including                      switching consists of two important issues namely packet
multimedia and interactive applications necessitating                   loss and delay. Inorder to provide better QoS in optical
bandwidth guarantees, minimum delay, less PLR, controlled               packet switching, PLR and delay should be reduced. Packet
jitter and etc. QoS provisioning seems therefore a mandatory            loss and delay are not new issues in optical networks;
task. Optical networks offer an extremely high traffic                  however minimum loss and delay provide better QoS in
bandwidth capable of providing communication channels                   Optical packet switching. In our earlier report the
for several hundred nodes. Thus, the network traffic requires           performance of 8B/10B code, Systematic code and Viterbi
the network to evolve by increasing transmission capacity of            code in optical transmission in terms of Bit Error Rate has
optical fibers as well as switching capability. There are three         been analyzed. In the physical layer, transmission is done on
switching schemes in optical networks namely optical                    bit by bit basis and Bit Error Rate has been reduced in the
circuit switching, optical burst switching (OBS) and optical            physical layer. When the bit errors in the physical layer are
packet switching (OPS). In the optical circuit switching, a             rectified, it will reduce the packet loss rates in the higher
dedicated end-to-end light path is established for each                 layers [2,3]. We have already reported that PLR has been
connection. Thus the transmission delay can be guaranteed

                                                                                                   ISSN 1947-5500
                                                           (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                     Vol. 8, No. 6, 2010

reduced in non-uniform traffic pattern [4]. We have also
implemented a RB algorithm for minimizing PLR in
buffered non-uniform traffic pattern of optical packet
switching mechanism [5].
 In this paper we have analyzed the asynchronous OPS in
terms of delay. Delay rate for fixed length packet and
variable packet length has been studied for various traffic
patterns viz. Non-uniform, Poisson and ON-OFF traffic
This paper has been organized as follows: Section II
describes the architecture of asynchronous OPS. In section
III, the analysis of delay rate is carried out for various traffic
patterns in asynchronous OPS. In section IV, results along
with discussions are presented and Section V deals with the
conclusion and future work.
                                                                                 Fig 1. Model of the switch in OPS network under consideration
               II. Description of Architecture
   The architecture used in this paper is presented in [4,5]. It             The following assumptions are made for the simulation:
has been reproduced for the reference. The size of switch
under consideration is N X N. The switch has F input fibers                Let ji denote the number of class i packets that arrive in a
and F output fibers. By utilizing WDM, each fiber provides                 time slot. The total number of packet arrivals at the fiber in a
N wavelengths to transport data with a capacity of C bps.                  time slot is k. That is j0 + j1 +… +jd-1 = k. In order to isolate
Buffers with the size of 5 are used in the OPS switch                      the service classes, the parameter li (0 ≤ li ≤ N) is
catering to each of the service classes. The switching                     introduced, which is the number of wavelengths reserved for
process in OPS can take one of the two main forms. It can                  Class i traffic in case of contention in a time slot. For a
be synchronous (time slotted) with the fixed packet length or              service class i, if ji < li (the number of incoming packets are
asynchronous (non-slotted) with variable packet lengths. In                less than the wavelengths assigned), it will result in ji - li
synchronous operation mode, all arriving packets have a                    free slots. For a service class i, if ji > li (the number of
fixed size and their arrival on each wavelength is                         incoming packets are            greater than the wavelengths
synchronized on a time-slot basis, where a time slot is the                assigned), resulting in li - ji overflow of packets.
time needed to transmit a single packet.                                   The RB algorithm [5] is implemented by introducing
   The operations of optical packet switching can be briefly               buffers. The RB algorithm is used for slotted OPS wherein
described as follows: When a packet arrives at the switch,                 buffers are used to avoid overlapping of packets. This
the packet header is extracted and processed electronically                algorithm is designed and used to improve the QoS of the
by the control module. While the header is processed, the                  networks in terms of reduction in PLR. By using the same
packet payload is buffered in the optical domain using FDL                 algorithm delay rate is found and analyzed in slotted OPS
processing buffers. Based on the destination, information                  with fixed packet lengths for various traffic patterns. Hence
extracted from the packet header and the control module                    QoS is improved in terms of reduction in PLR and delay
decides to which output fiber/wavelength the packet is                     [4,5]. In this paper the same algorithm is implemented in
switched and configures the switch accordingly. Contention                 asynchronous OPS for the packets of variable lengths.
occurs when two or more packets are assigned to the same
output port on the same wavelength at the same time [6 and                                    III. Operating Principle
7]. The network has d service classes, ranging from service                Operation of optical packet switch in a synchronous manner
class 0 to service class d-1. We assumed that the output on a              with fixed length of packets is explained in [5]. Here we
single fiber/wavelength as the tagged fiber/wavelength.                    assume that optical packet switch operates in an
Delay is calculated for class i traffic at the tagged output               asynchronous manner with variable length of packets.
fiber. Fig1 shows a switch for packet arrivals to a tagged                 Analysis of delay rate for variable packet sizes in
output fiber must originate from one of the FN input                       asynchronous OPS using three types of traffic patterns viz.
wavelengths.                                                               Non-uniform, Poisson and ON-OFF traffic models is
                                                                           presented in this paper. In contrast to [8], immaterial of
                                                                           packet size, allotted time slots remain the same and no
                                                                           shifting of time slot allocation is done.
                                                                           In non-uniform traffic pattern all nodes are not to receive
                                                                           and send similar volumes of traffic [4, 9]. The number of
                                                                           packets arrived and transmitted of packets is not equal.
                                                                           There is an incoming packet for every slot. We assume that

                                                                                                          ISSN 1947-5500
                                                         (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                   Vol. 8, No. 6, 2010

each packet has equal probability of 1/N being addressed to             this paper, at every node there should be arrival(s) of
any given output port and successive packets that arrive at             different classes of packets. In ON-OFF model, ON periods
the tagged output/wavelength are independent. Also, the                 and OFF periods occur at each node for different classes.
packet arrival time at the input and transmission time to the           When one class is in ON period, other classes may be in
output port are not equal. This is due to randomness of                 OFF period at that particular node and OFF period of one
packet arrival. This increases the occupancy of the free                class is used by the other classes for transmitting packets.
slots. In Poisson traffic model, packet arrivals are random             Also, other possibilities are (1) all classes may be in OFF
and are mutually independent. The Poisson distribution can              period, (2) all classes may be in ON period and (3) some of
be obtained for packet arrivals during an infinitesimal short           the classes may be in ON period and rest may be in OFF
period of time λ t, where λ is called the arrival rate. Packet          period.
arrival at the output fiber is a single Poisson process with λ.         We assume that the switch is having buffers. In RB
In Poisson model, the number of arrivals in non-overlapping             algorithm, the packets use the wavelength according to their
intervals is statistically independent. The arrival rate λ is           service classes. If there is flow of packets into the ports
expressed as the average number of arrivals during a unit of            with a specified service class, the incoming packets with
time. The time distance between consecutive packet arrivals             assigned wavelengths occupy the ports as per the assigned
is exponentially distributed [10]. However Poisson arrival              service class. When the assigned wavelengths in one service
model is not an accurate model considering packet arrivals              class are occupied, it checks for the free wavelengths of
at the tagged output fiber/wavelength in OPS. The Poisson               other service classes and the packets will occupy the free
arrival model assumes an infinite number of sources, which              slots in the other service classes. When the assigned
is not the case in a real switch. When using a Poisson arrival          wavelengths are completely occupied in all the ports, the
model, there is the possibility of independency between the             packets overflow. By introducing buffers, the packets that
service time and the packet inter-arrival time [11].                    overflow are saved. When a free slot is not available for an
Bursty traffic is also known as ON-OFF traffic model. Both              incoming packet, instead of dropping that packet, it will be
the ON and OFF periods are distributed using exponential                saved in the buffer which is provided in the switch. Before
distribution with the mean 1 μ and 1 λ respectively. It is              entering the buffer, a bit is added in the packet header for
                                                                        the purpose of reservation with respect to their service
an alternating process where an OFF period follows an ON
                                                                        classes. Whenever free slots are available, the packets in the
period, and an ON period follows an OFF period. During
                                                                        buffer occupy free slots. Buffered packets will have the
ON periods, series of packets are transmitted from the
                                                                        priority over the incoming packets. In the FF algorithm, all
source node and the time is called active periods. OFF
                                                                        wavelengths are numbered in a certain order, for example
periods are called passive periods and no packets are
                                                                        ascending order from 0 to W-1, where W is a number of
transmitted from the source. Active periods of a source are
                                                                        wavelengths. When the deciding port attempts to assign a
exponentially distributed with one specific mean value, and
                                                                        wavelength, it sequentially searches all wavelengths in an
passive periods are exponentially distributed with another
                                                                        ascending order and assigns the first available wavelength
mean value. During an active period, packets are generated
                                                                        [14]. In class based model, each node transmits the packets
at regular periods. The most commonly used VOIP traffic
                                                                        according to their classes. Buffers are placed in the port for
model is based on a two-state on-off model of a single voice
                                                                        every class. In port based model, wavelengths are placed in
source. When a voice source is transmitted, it is in the ON
                                                                        a sequential order. Irrespective of the class, the available
state, and when the voice source is silent, it is in the OFF
                                                                        wavelength is used by the incoming packets in a sequential
state; and the ON and OFF states appear alternatively. ON-
                                                                        order and buffers are only placed in each port.
OFF sources, each of which exhibits a phenomenon called
                                                                        FF algorithm is implemented in port based and packets are
the “Noah Effect” resulting in self similar aggregate traffic.
                                                                        transmitted according to their wavelengths, whereas
The Noah Effect for an individual ON-OFF source model
                                                                        transmission of packets is class based in RB algorithm and
results in ON and OFF periods, i.e. “train lengths” and
                                                                        packets are transmitted according to their service classes and
“intertrain distances” that can be very large without
                                                                        wavelengths. Thus the drop rates of packets are reduced in
negligible probability [12 and 13]. The number of packet
                                                                        optical networks resulting in improved QoS. The delay rate
arrivals divides the timeslot and produces the time slice
                                                                        is found and analyzed in asynchronous OPS for various
which is utilized for packet transmission. Hence the packet
                                                                        traffic patterns viz. Non-uniform, Poisson and ON-OFF
arrival rate is random, time slice is determined according to
                                                                        traffic models for various service classes with packets of
randomness of the packet arrival. ON and OFF periods are
                                                                        variable lengths. The delay rates for RB algorithm and FF
used with their own mean values and using the same mean
                                                                        algorithm are found and compared.
values, various packets arrive and are transmitted during ON
                                                                        For fixed size packets and variable size packets in OPS,
period and idling occurs during the OFF period. During ON
                                                                        delay rate is encounted by implementing RB algorithm. The
period, packet is transmitted and there is no flow of packet
                                                                        packet includes payload and header. Fig 2 shows the packet
during OFF period. In this model, FN independent state
                                                                        header. For fixed size packets, size considered is 512 bytes.
model generate packet arrivals at a tagged output fiber. In
                                                                        For variable packet size, the range of packet size is in the

                                                                                                   ISSN 1947-5500
                                                                 (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                           Vol. 8, No. 6, 2010

range of 512 bytes and 2k bytes. 20 bytes is included as                     slot. Buffers are used along with RB technique, 240 packets
header along with the payload invariably for any type of                     are chosen with an Erlang load of 1.5.
packets. Variable size packets are used in VoIP applications.
In variable packet size, the size has been controlled by the
application. Packet sizes of the range of 1024 to 2048 bytes
show good efficiency in terms of bandwidth and reliability
in Digital Video Broadcasting [15]. Packet size is measured
using uniform min and max distribution. Packet size is
chosen depending on the application.
  Source     Desti     Source      Desti     Packet    Time    Flow
    IP      -nation     Port      -nation   Sequence   Stamp     id
  address     IP                   Port        no
     4          4          2         2         2         4       2
   bytes      bytes      bytes     bytes     bytes     bytes   bytes
  Fig. 2 Structure of the packet header
When a packet is send from one node to other, the following
delays occur: (1) transmission delay (time required to send                    Fig 3. Delay rate for various traffic patterns for service class 3 using
                                                                               reservation bit technique.
all bits of packet into the wire), (2) propagation delay (the
time taken by the packet to travel through the wire), (3)
processing delay (the time taken to handle the packet in the
network system), and (4) queuing delay (the time taken is
buffering the packet before it can be sent). In most cases, the
delay (2) and (4) are considered in simulations and
measurements. The transmission delay (1) is usually small
for fast links and small packets and is therefore not
considered. Traditionally, the processing delay (3) has also
been negligible [16]. In our measurements, we consider the
delay (2) and (4). The mean delay for the above said traffic
pattern is found using equation (1).
   TD = TPr opagation + TQueue                   (1)
Initially, we calculate the propagation delay that occurs                      g 4. Delay rate for various traffic patterns for service class 3 using First-
when a packet travels from the source to the destination.                      Fit wavelength assignment algorithm
Next, the queue delay experienced by a packet is calculated
using equation (2). This delay is due to waiting period of the
packet in the queue. A packet is in a queue, if a free
wavelength is not available at that particular time slot.
TQueue =
                ∑ (T )
                i =0
                       i                                (2)

where Ti is the transmission time of class i packets at
particular time slice.
Summation of the waiting time in the buffer and the
transmission time between source node and destination node
through the switch is considered as delay and the same is
found for the above said traffic patterns.
IV. Results and Discussions
   The delay values for the fixed length packets in slotted                    Fig 5. Delay rate for various traffic patterns for service class 4 using
OPS using RB algorithm is studied and is also compared to                      reservation bit technique
the FF algorithm in our earlier paper [5]. In this paper, a
detailed analysis is carried out to find delay in asynchronous
OPS for variable length packet and is compared to FF
We consider 240 packets for the simulation purpose. Delay
for class i packets are calculated in the tagged fiber.
Wavelength assigned is 16 and total time slot chosen is 10,
hence this architecture can transmit 160 packets in a time

                                                                                                               ISSN 1947-5500
                                                                     (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                               Vol. 8, No. 6, 2010

  Fig 6. Delay rate for various traffic patterns for service class 4 using
               First-Fit wavelength assignment algorithm

                                                                                                        Fig 9. Delay rate comparison

Fig 7. Delay rate for various traffic patterns for service class 5 using
reservation bit technique

                                                                                                   Fig 10. Comparison of data transmission

                                                                                      In service class 3, RB technique has 15 buffers, each service
                                                                                      class has 5 buffers, but in FF algorithm, each port has 5
                                                                                      buffers and the total number of buffers is 20. 10.96ms,
                                                                                      10.88ms and 9.83ms are the delay values while employing
                                                                           Fi         FF algorithm and 7.55ms, 7.79ms and 7.91ms are the delay
g 8. Delay rate for various traffic patterns for service class 5 using First-         values while employing RB technique in asynchronous OPS
                  Fit wavelength assignment algorithm                                 using Non-Uniform, ON-OFF and Poisson traffic model
                                                                                      respectively for Service class 3 and the same is shown in
                                                                                      figs 3 and 4.
                                                                                      In Service class 4, both the techniques have 20 buffers.
                                                                                      10.94ms, 10.56ms and 10.18ms are the delay values while
                                                                                      employing FF algorithm and 7.77ms, 8.01ms and 7.561ms
                                                                                      are the delay values while employing RB technique in
                                                                                      asynchronous OPS using Non-Uniform, ON-OFF and
                                                                                      Poisson traffic model respectively for Service class 4 and

                                                                                                                  ISSN 1947-5500
                                                       (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                 Vol. 8, No. 6, 2010

the same is shown in figs 5 and 6. From these it is seen that         uniform traffic pattern result in better Quality of service
both the techniques have same amount of buffer. FF                    compared to ON-OFF model and Poisson model. At the
algorithm exhibits more delay, but delay is less in our               same time ON-OFF traffic pattern have better QoS when
approach.                                                             compared to Poisson process if OFF periods of one service
While in service class 5, RB techniques have 25 buffers and           classes are more efficiently utilized by other service classes.
FF algorithm need 20 buffers. 10.09ms, 10.88ms and                      [1] Biao Chen and Jianping , “ Hybrid Switching and P-Routing for
                                                                        Optical Burst Switching Networks”, IEEE Journal on Selected areas in
9.50ms are the delay values while employing FF algorithm                communications, vol 21, no 7,pp.1071-1080, Sep 2003.
and 7.1ms, 6.27ms and 6.48ms are the delay values while                 [2] A.Kavitha, V.Rajamani and P.AnandhaKumar, “Performance
employing RB technique in asynchronous OPS using Non-                   analysis of Coding Techniques to find BER in Optical Transmission”,
Uniform, ON-OFF and Poisson traffic model respectively                  IEEE 1st International Conference on Advanced Computing- ICAC 2009,
                                                                        13-15 Dec. 2009 Page(s):21 - 27
for Service class 5 and the same is shown in figs 7 and 8.              [3] A.Kavitha, V.Rajamani and P.AnandhaKumar, “Evaluation of BER
 For all the service classes under consideration, buffers are           in Optical Packet Switching using Various Coding Schemes” IEEE
more or less the same for RB technique and FF algorithm,                Transaction on Optical Communication and Networking (under review).
whereas the delay rate is slightly higher in FF algorithm.              [4] A.Kavitha, V.Rajamani, “Performance Analysis of Slotted Optical
                                                                        Switching Scheme using Non-Uniform traffic” – Journal of Optical
The above statement is true when the class based                        Communications, Vol. 29, July 2008, pp.107-111.
transmission is compared with port based transmission.                  [5] A.Kavitha, V.Rajamani and P.AnandhaKumar, ”Performance
 Simulation results show that for all service classes under             Analysis of Slotted Optical Packet Switching Scheme in Non-Uniform
any type of traffic pattern, class based model produces 29%             Traffic Pattern Using Reservation Bit Technique”- Selected for
                                                                        publication- INFOCOMP, Journal of Computer Science.
reduction of delay rate when compared to port based model                [6] H. Øverby and N. Stol, “Evaluating and comparing two different
and the same is shown in fig 9. In RB technique the buffered            service differentiation methods for OPS: the wavelength allocation
packets with respect to their classes will occupy the free              algorithm and the preemptive drop policy,” in Proc. 3rd Int. Conf.
slots of the corresponding service class wavelengths on First           Networking, vol. 1, Feb. 2004, pp. 8-15.
                                                                        [7] S.Bjornstad, N.Stol and D.R.Hjelme, “A highly efficient optical
Come First Serve basis which reduces the waiting time in                packet switching node design supporting guaranteed service” in proc. Of
the buffer whereas in FF algorithm wavelength utilization is            SPIE, Vol 4910, 2002, pp.63-74.
sequential, so buffered packets wait until they are serviced            [8] BO Wen, Ramakrishna Shenai, and Krishna Sivalingam,” Routing
with the next sequential order of wavelengths. Thus delay               Wavelength and Time-Slot-Assignment: Algorithms for Wavelength-
                                                                        Routed Optical WDM/TDM Networks”, Journal of Lightwave
rate is less in asynchronous OPS when RB technique is                   Technology, vol 23, no 9, pp.2598-2609,Sep 2005.
employed. The delays are improved much in our algorithm.                [9] Adisak Mekkittikul, Nick McKeown “Scheduling VOQ Switches
This is due to the class based transmission.                            under Non-Uniform Traffic”, CSL Technical Report, CSL-TR 97-747,
Fig 10 shows the total number of transmitted bytes per slot.            Stanford University, 1997 Stanford University,Standford.
                                                                        [10] Wuyi Yue, Yutaka takahashi,hideaki tagaki, “Advances in
It is shown that more number of packets is transmitted in               Queueing theory and network application:, Springer,ISBN: 978-0-387-
class based model for all service classes for all traffic               09702-2, e-ISBN: 978-0-387-09703-9.
patterns under consideration when compared to port based                [11] Harald Overby and N.Stol “ Quality of Service in synchronous
model. Hence class based model produces lesser delay as                 bufferless optical packet switched networks” Kluwer Telecomm. Sys.
                                                                        Vol 27, 2004. pp. 151- 179.
well as more number of bytes transmission when RB                       [12]Mihails Kulikos and Ernests Petersons”Remarks Regarding
technique is employed. It is also shown that non-uniform                Queueing Model and Packet Loss Probability for the Traffic with self –
traffic pattern produces lesser delay when compared to ON-              Similar Characteristics”, Networks”, International Journal of Computer
OFF and Poisson model.                                                  Science 3;2,Spring 2008,pp. 85-90.
                                                                        [13] Eric W.M. Wong and Moshe Zukerman,” Bandwidth and Buffer
                                                                        Tradeoffs in Optical Packet Switching”, Journal of Lightwave
V. Conclusion                                                           Technology, vol 24, no 12, Dec 2006, pp 4790- 4798.
The delay rates for the Non-uniform, Poisson and ON-OFF                  [14] Xuehong Sun, Yuunhao Li, Ioannis Lambadaris and Yiqiang
traffic models for various service classes are analyzed.                Q.Zhao, Performmance Analysis of First – Fit Wavelength Assignment
                                                                        Algorithm in Optical Networks”, IEEE 7th International Conference on
Minimum delay has been achieved in all service classes                  Telecommunications – ConTEL2003, June11-13, 2003, pp. 403-409.
under consideration by using reservation bit technique. It              [15]Vadakital, V.K.M. Hannuksela, M.M. Razaei, M. Gabbouj,
provides lesser delay for all service classes for fixed and             M,” Optimal IP Packet Size for Efficient Data Transmission in DVB-H”,
variable length packets when compared to first-fit                      Proceedings of the 7th Nordic ,IEEE Signal Processing Symposium, pp.
                                                                        82-85, 7-9 June 2006.
wavelength assignment algorithm. It is seen from our                    [16] Ramaswamy Ramaswamy, Ning Weng and Tilman Wolf,
simulation, Poisson arrival model which is assumed in the               “Characterizing Network Processing Delay”, Proc. in Globecom 2004,
analysis approximates a more realistic model wherein all                IEEE Communication Society, pp.1629- 1634.
input wavelengths are modelled as independent on/off
processes with exponential holding time. Also we have
presented a comparative study of reservation bit technique                                      AUTHORS PROFILE
and first-fit wavelength assignment algorithm for
synchronous and asynchronous OPS. It is concluded that in
Optical packet switching reservation bit technique reduces
delay; hence QoS is improved and at the same time Non-

                                                                                                      ISSN 1947-5500
                                                              (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                        Vol. 8, No. 6, 2010

                                  A.Kavitha received the B.E
                                  degree in Electronics and
                                  Communication Engineering
                                  from      Madurai      Kamaraj
                                  University, India in 1997. The
                                  Master of Engineering degree
                                  in        Computer         and
                                  Communication Engineering
                                  from Anna University, Chennai
                                  in 2004 and currently pursuing
                                  Ph.D    degree      in  Optical
                                  Communication Networks in
                                  Anna University, Chennai. At
present she is working as a Senior Lecturer in Chettinad College
of Engineering and Technology, Karur. She has published more
than 10 papers in referred National and International
conferences/Journals. Her area of interest includes Networks,
Computer Architecture, Digital Communication and etc.

                                V.Rajamani received the B.E
                               degree      in     Electronics   and
                               Communication Engineering from
                               National Engineering College, Anna
                               University, India in 1990. The
                               Master of Engineering in Applied
                               Electronics     from      Government
                               College of Technology, Bharathiyar
                               University Coimbatore in the year
                               1995 and the Ph.D. degree in
Electronics Engineering from Institute of Technology, Banaras
Hindu University, Varanasi in 1999. He started his carrier as
Lecturer in Mohamed Sathak Engineering College from 1991
onwards. He has held various positions in various Engineering
Colleges. At present he is working as a Principal in Indra
Ganesan College of Engineering, Tiruchirappalli. He has
completed a project under AICTE - RPS scheme successfully. He
has published more than 80 papers in referred National and
International Journals/ conferences. His area of interest includes
Device     modeling,     VLSI,    Image       processing,     Optical
Communication and system.

P.Anandhakumar received the B.E degree in Electronics and
Communication Engineering from University of Madras, India in
1994. The Master of Engineering degree in Computer Science
and Engineering from Bharathiyar University in 1997 and Ph.D
degree in Computer Science and Engg. from Anna University,
Chennai in the year 2006.At present he is working as a Assistant
Professor in Madras Institute of Technology, Chennai. He
published more than 50 papers in referred National and
International conferences/Journals. His area of interest includes
Digital Communication, Soft Computing, Robotics and etc.

                                                                                                      ISSN 1947-5500

Description: IJCSIS is an open access publishing venue for research in general computer science and information security. Target Audience: IT academics, university IT faculties; industry IT departments; government departments; the mobile industry and computing industry. Coverage includes: security infrastructures, network security: Internet security, content protection, cryptography, steganography and formal methods in information security; computer science, computer applications, multimedia systems, software, information systems, intelligent systems, web services, data mining, wireless communication, networking and technologies, innovation technology and management. The average paper acceptance rate for IJCSIS issues is kept at 25-30% with an aim to provide selective research work of quality in the areas of computer science and engineering. Thanks for your contributions in September 2010 issue and we are grateful to the experienced team of reviewers for providing valuable comments.