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SIP and RSW: A Comparative Evaluation Study

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					                                                              (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                        Vol. 8, No. 8, 2010
                            SIP and RSW: A Comparative Evaluation Study
                             Mahmoud Baklizi1, Nibras Abdullah1, Omar Abouabdalla1, Sima Ahmadpour1.
                                        1: National Advanced IPv6 Centre of Excellence
                                                    1: Universiti Sains Malaysia
                                                        1: Penang, Malaysia
                                      1: {mbaklizi, abdullahfaqera, omar, sima}@nav6.org


                                                                          oriented programming languages such as Java and Perl. These
Abstract— Voice over internet protocol (VoIP) is a technology             allow easy debugging, and most importantly make SIP flexible
that uses Internet to transmit voice digital information. The             and extensible. (ii) Less signaling. (iii) transport-layer-
Session Initiation Protocol (SIP) and Real time Switching (RSW)           protocol neutral (iv) parallel search [5][7].
are signaling protocols that emerged as a new VoIP which gained
popularity among VoIP products. In literature, many
comparative studies have been conducted to evaluate signaling
                                                                          Real time Switching appeared in late 1993 as a control
protocols, but none of them addressed the targeted protocols. In          mechanism for multimedia conferencing. It was designed by
this paper, we make a comparative evaluation and analysis for             Network Research Group (NRG) in school of computer
SIP and RSW using Mean Opinion Score rating (MOS). We                     science-University Science Malaysia (USM) .The goal of
found that RSW performs better than SIP under different                   RSW Control Criteria is how to conduct a conference around a
networks in terms of (packet delays).                                     meeting table [8][9][10]. Moreover, RSW is used to handle
                                                                          two issues in multimedia conferencing. The first one is to
  Keywords- VoIP; MOS; InterAsterisk eXchange Protocol; Real              handle the confusion generated while everyone tries to speak
Time Switching Control Criteria and Session Initiation protocol.          at the same time. The second issue is the tremendous amount
                                                                          of network traffic generated by all participating sites [6].
                       I.     INTRODUCTION
                                                                          More recently, InterAsterisk exchange protocol has been
Nowadays, the use of distributed computer network systems                 emerged as new protocol that improved the voice quality. It
has been increased in many areas of government, academia                  has also many features such as simplicity, NAT-friendliness,
and industry. Video conferencing system is one of computer-               efficiency and robustness [2][3]. There are several goals for
based communication applications. The idea of video                       this protocol. The main goals of this protocol are (i)
conferencing appeared for the first time in the 1920s [1]. The            Minimizing bandwidth usage for signaling and media transfer,
task of video conferencing concentrates on individuals to be              with a particular emphasis on voice (ii) Ensuring NAT
together in space and time, and makes groups more effective               transparency (iii) Ability to exchange dial plans (iv) Efficient
at their work by applying different services such as telephony            implementation of intercom and paging features. On the other
service over IP networks that are known as IP telephony or                hand, IAX can be used with different types of streaming media
Voice over IP. VoIP communication usually consists of two                 such as video and voice calls [4]. In this paper, we have
protocols: (i) Signaling protocols that are used to setup a voice         selected two case studies that depend on IAX protocol. In the
conversation and manage voice sessions (ii) Media transfer                first case study, the researchers made comparison between
protocols that are used for exchanging voice data traffic during          IAX and RSW [3]. While in the second case study the
one session lifetime. [2]. One of the most important functions            researchers compared between IAX and SIP [2]. According to
in the VoIP infrastructure is signaling session. Signaling                the last two comparisons, we have made a comparative
session should be by any VoIP protocol before transmitting                evaluation of SIP and RSW by using Mean Opinion Score
any media type. Therefore, it allows various network                      rating (MOS).
components to communicate with each other to setup and to
tear down calls [3]. Recently, there is strong focus on the
development of scalable VoIP protocols, such as SIP, RSW                                       II.   RELATED WORK
and IAX.
                                                                          Before transmitting any media, the signaling session, which is
Large efforts have been done to study SIP. It was standardized            the most important function in VoIP, allows different network
in the IETF (Internet Engineering Task Force) RFC 2543 and                components to communicate between each other to set up and
further extended in RFC 3261.It is used for creating,                     terminate calls. Mean Opinion Score (MOS) is used as a
modifying, and terminating sessions with one or more                      method to assess call quality. In addition, it is used to measure
participants [5][6].                                                      subjective voice quality. To measure network performance, we
                                                                          use the MOS rating which is the most widely used assessment
                                                                          technique. The listening subjects were given a scale from 1 to
Session Initiation Protocol has many features: (i) the service of
text-based which allows easy implementation in object



                                                                    117                              http://sites.google.com/site/ijcsis/
                                                                                                     ISSN 1947-5500
                                                          (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                    Vol. 8, No. 8, 2010
5, where 1 = bad, 2 = poor, 3 = fair, 4 = good, and 5 =               that the packet delay in IAX is better than that in SIP and
excellent [11].                                                       RSW. The gained results are extracted using the SPSS
                                                                      statistical tool. The Interclass Correlation Coefficient
Recently, there are many researchers concentrated on this             statistical test is used to analyze IAX with comparison to the
function and compared between different VoIP protocols. The           previous two studies. As a result, the correlation between the
study conducted by [2] compared the performance between               two variables is high. The single measure Interclass
IAX and SIP protocols. They have indicated that both                  correlation coefficient is 0.995, the test value for absolute
protocols perform comparably in the presence of fixed delay.          agreement is 0.99999, and p is approximately equal to 1. The
Therefore IAX appeared to perform slightly better as shown in         IAX protocol regression formula and curve were identical in
Figure 1 [2].                                                         previous two studies. An indirect comparison between RSW
                                                                      and SIP was made directly in terms of fixed packet delay.
                                                                      Figure 3 indicates that the RSW protocol performs slightly
                                                                      better in the presence of fixed packet delay than SIP protocol.




            Figure 1: Packet Delay - SIP versus IAX [2]


The researchers in [3] compared the performance between                               Figure 3: Packet Delay - SIP versus RSW
IAX and RSW protocols. They indicated that both protocols
perform comparably in the presence of fixed delay. Therefore
IAX appeared to perform slightly better than RSW as shown                                          CONCLUSION
in Figure 2 [3].
                                                                      This paper suited the performance of the RSW and SIP in term
                                                                      of packet delay. From the evaluation and analysis, we
                                                                      conclude that RSW achieves more improvement than SIP in
                                                                      VoIP in relation to packet delay via the MOS score. Further
                                                                      research on RSW control criteria and SIP protocols and their
                                                                      performance under various conditions is recommended.

                                                                                                Acknowledgment

                                                                      We would like to thank Hani Mimi and Abdullah Dahbali
                                                                      for their support and guidance throughout the study and
                                                                      analysis.


                                                                                                   REFERENCES
            Figure 2: Packet Delay - RSW versus IAX [3]
                                                                      [1]   E. M. Schooler, “Conferencing and collaborative computing,”
                                                                            Multimedia Systems. Vol. 4, pp. 210-225, 1996
                                                                      [2]   T. Abbasi, S. Prasad, N. Seddigh, and I. Lambadaris, "A comparative
                                                                            study of the SIP and IAX VoIP protocols," Electrical and Computer
              III.   ANALYSIS AND EVALUATION                                Engineering, Canadian Conference, pp.179-183, 1-4 May 2005
                                                                      [3]   S. Manjur, M. Mosleh, O. Abouabdalla, W. Tat , and A. Manasrah,
The predicated evaluation is based on previous two                          “Comparative Evaluation and Analysis of IAX and RSW,”(IJCSIS).Vol.
                                                                            6,2009
comparisons that were conducted by [2] and [3]. We can see



                                                                118                                  http://sites.google.com/site/ijcsis/
                                                                                                     ISSN 1947-5500
                                                                          (IJCSIS) International Journal of Computer Science and Information Security,
                                                                                                                                    Vol. 8, No. 8, 2010
[4]  M. Spencer, F. Miller, “IAX Protocol Description,” February 2005,
     http://www.cornfed.com/iax.pdf. 
[5] I. Dalgic and H. Fang, “Comparison of H.323 and SIP for IP telephony
     signaling,” in Proc. of Photonics East, (Boston, Massachusetts), SPIE,
     Sept. 1999.
[6] O. Abouabdalla, R. Sureswaran, "Enable Communications between The
     RSW Control Criteria and SIP Using R2SP," Distributed Frameworks
     for Multimedia Applications, 2006. The 2nd International Conference
     on, vol., no., pp.1-7, May 2006.
[7] Y. Zhang, “SIP-based VoIP network and its interworking with the
     PSTN,” Electronics & Communication Engineering Journal, December
     2002, Volume 16, Issue 6, pg 273-282
[8] R. Sureswaran, “A Reflector Based System to Support the RSW
     Multimedia Conferencing Control Criteria,” IASTED International
     Conference on Networks, Orlando, January 1996.
[9] R. Sureswaran, Subramanian, R.K, H. Guyennet, and M. Trehel, “Using
     the RSW Control Criteria To Create A Distributed Environment for
     Multimedia Conferencing,” In Proceedings of REDECs '97. Penang,                    .
     Malaysia. 27-29 November 1997.
[10] R. Sureswaran, “A Distributed Architecture to support Multimedia
     Applications Over the Internet and Corporate Intranets,” In Proceedings
     of SEACOMM '98. Penang, Malaysia. 12-14 August 1998.
[11] http://www.itu.int/rec/T-REC-P.800/en


                                Mahmoud Khalid Baklizi is a researcher
                                pursuing his PhD in Computer Science at the
                                National Advanced IPv6 Center of
                                Excellence in University Sains Malaysia. He
                                received his first degree in Computer Science
                                from Yarmouk University, Jordan, 2002 and
                                his Master degree in Computer Information
                                System from the Arab Academy for Banking
                                and Financial Sciences, Jordan in 2008. His
                                research area of interest includes Multimedia
                                Networking.
                                Nibras Abdullah Faqera received his
                                Bachelor of Engineering from College of
                                Engineering and Petroleum, Hadhramout
                                University of science and technology,
                                Yemen, 2003. He obtained his Master of
                                Computer Science from School of Computer
                                Science, Universiti Sains Malaysia in 2010.
                                He is academic staff member in Hodeidah
                                University, Yemen. He is researcher pursuing
                                his PhD in Computer Science at the National
                                Advanced IPv6 Center of Excellence in
                                University Sains Malaysia. His research area
of interest includes Multimedia Conferencing System (MCS).
                                  Dr. Omar Amer Abouabdalla is a senior
                                  lecturer and head of the technical department
                                  in the National Advanced IPv6 Centre
                                  (NAv6) - University Science Malaysia
                                  (USM). Dr. Omar is the Chairman of
                                  multimedia working group (a sub working
                                  groupin APAN), Asia Pacfic Advanced
                                  Network (APAN) is a high bandwidth
                                  network that will interconnect the Asia
                                  Pacifc Countries. He is also a member of
                                  Internet Engineering Task Force (IETF) and
a member of Editorial Board for Journal of IT in Asia. Dr. Omar is heavily
involved in researches carried by NAv6 center, such as Multimedia
Conferencing System (MCS) and IPv6 over Fiber project. He has more than
five years experience in the field of IPv6 and more than ten years in the field
of Multimedia Network.




                                                                                  119                          http://sites.google.com/site/ijcsis/
                                                                                                               ISSN 1947-5500