Performance Analysis of Smart Optical Burst Switching Networks for Different Signaling Protocols

Transcription

1 Sart Coputing Review, vol. 5, no. 5, October Sart Coputing Review Perforance Analysis of Sart Optical Burst Switching Networks for Different Signaling Protocols Mykhailo Klyash, Mykola Kaidan, and Stepan Duych Lviv Polytechnic National University /Lviv 79013, Ukraine / {kliash@lp.edu.ua, kaidan_k@ail.ru, stiv.duych@gail.co, taras.aksyyuk.ua@ieee.org} *Corresponding Author: Mykhailo Klyash Received July 15, 2015; Revised Septeber 20, 2015; Accepted Septeber 16, 2015; Published October 31, 2015 Abstract: A future optical transport network needs an extreely high capacity to satisfy the rapid increase in traffic. Many technologies have been developed to increase throughput and energy efficiency and siplify the deployent of optical transport networks. Internet Protocol traffic transission precedes optical transport networks in requiring new approaches for network nodes. Although optical fiber has a treendous capacity, switching nodes liit the perforance of optical networks. An optical burst switched network concept has been introduced as a proising solution to overcoe this proble. Optical burst switched technology effectively utilizes the advantages of both circuit switching and packet switching networks, and also eliinates their drawbacks. Two iportant issues in achieving the best perforance in optical burst switched networks are scheduling bursts and signaling protocols. In this paper, we provide a coprehensive analysis of optical burst switched signaling protocols. We study three protocols for signaling in optical burst switched networks that are used for various traffic types. The Tell-and-Wait and Just Enough Tie protocols are used in extree cases of loss-sensitive and delay-sensitive traffic, respectively. The third signaling protocol, called Interediate Note Initiation, is a proising solution with an ability to adjust paraeters depending upon traffic requireents. We analyze the blocking probability of core nodes with respect to the nuber of buffers and wavelengths for each signaling protocol. The siulation results show that when the nuber of optical buffers are five or higher, blocking probability tends to be zero, regardless of the nuber of wavelengths. Therefore, this tends to decrease loss due to a burst, and iproves the overall perforance of optical burst switched networks. The burst outstripping proble in optical fiber has been solved by deterining a proper buffering policy for each burst, after considering the burst priorities and tie delays between consistent bursts. DOI: /sartcr

2 Sart Coputing Review, vol. 5, no. 5, October Keywords: blocking probability, buffering, Interediate Node Initiation, Just Enough Tie, Sart Optical Burst Switching, Tell-and-Wait. Introduction T oday we are facing a rapid growth in inforation services, which are ubiquitously available to end users regardless of the device (sartphone, laptop, tablet, etc.) they use. Modern inforation systes ust provide instant data transission between end users, enterprises, and global cloud systes to satisfy ever-increasing requireents. To integrate distant separated systes into one ubiquitous inforation syste, optical networks are widely deployed around the globe by connecting continents and countries through undersea and terrestrial links. Optical networks have been constantly developed during the past decades to support these growing requireents. Nowadays, an extreely huge nuber of Internet-connected devices (around 30 billion) has given rise to exponential traffic growth (ore than 2 zettabytes per year). In the near future, we expect an even ore rapid increase in Internet Protocol (IP) traffic that will be triggered by upcoing 5G obile networks, the Internet of Things (IoT), Mobile Cloud and Fog Coputing systes [1,2]. Consequently, traffic volue in optical transport networks needs to increase. At present, optical networks have attained treendous capacity due to the ipleentation of Dense Wavelength Division Multiplexing (DWDM). However, bottlenecks in switching nodes liit overall network perforance [3]. Rapidly-variable IP traffic has led to low perforance in wavelength-switching technologies [4]. Techniques based on a new concept called IP over DWDM (IPoDWDM) [5] for packet switching have been developed to increase the flexibility of optical networks. The packet switching techniques are able to handle high traffic variability. However, the high overhead produced by signaling data decreases the bandwidth utilization factor. A proising IPoDWDM-based ipleentation is sart optical burst switching (OBS) technology [6]. OBS cobines the advantages of both circuit switching and packet switching technologies. This allows the developent of an elastic optical transport network with flexible traffic anageent [7]. OBS networks transit IP packets that are associated with logical bursts. Bursts logically cobine IP packets that share the sae destination and have siilar service requireents. Packets associated with different bursts are separated according to the destination address and throughput requireents [8]. Each burst is affiliated with a Burst Header Packet (BHP), which contains inforation about the destination address, Quality of Service (QoS) requireents and additional inforation to support scheduling and switching [9-11]. OBS networks are based on two types of nodes: edge nodes and core nodes [12]. The functions of an edge node includes the aggregation of data flows fro access networks, assebling IP packets into bursts, and generating BHPs. In reverse, edge node analyses BHPs, disassebles bursts into IP packets, and distributes data flows between access networks. The function of the core node is the routing and switching of bursts according to BHP inforation. The ain feature of a core node is all-optical switching and transparent transission. In this case, two edge nodes are able to transit large volues of data through virtual channels with high throughputs and low latency [13]. To attain a high perforance fro an optical network, BHPs are transitted ahead of corresponding bursts. This allows us to create virtual channels in the ost effective way, when a channel is established right before a burst transission. However, odern IP networks are ulti-service and featured under various traffic types. This significantly coplicates routing, switching, and scheduling in both edge nodes and core nodes due to differing throughput, latency, and packet loss requireents for each traffic type. Therefore, different signaling protocols such as Just Enough Tie (JET), Tell-and-Wait (TAW), and Interediate Node Initiation (INI) [14] were developed for OBS networks. In this paper, we analyze the perforance of existing signaling protocols for OBS networks in ters of blocking probability in core nodes and end-to-end delay. We start by analyzing the basic principles of a sart optical burst switching network in the second section. Then, we describe different signaling protocols, which are used in OBS, and derive delay equations for each protocol in the third section. In the fourth section, we derive equations for blocking probability in the core node and deterine the optial buffer by running a probabilistic siulation. The tie delays in burst transission for different signaling protocols are studied in the fifth section. Finally, we conclude this paper in the sixth section. Basic principles of sart optical burst switching Sart optical burst switching is the next step in the evolution of an optical transport network, and is positioned between circuit switched NG-SDH networks and future all-optical packet switched networks. OBS effectively utilizes the advantages of both circuit and packet-switched networks while eliinating their drawbacks. This allows elasticity in the high fluctuation of IP traffic in addition to effective bandwidth utilization. The data transission in optical burst switched networks works as follows. First, edge nodes aggregate all data flows and analyzes each IP packet. Second, all IP packets

3 380 Klyash et. al: Perforance Analysis of Sart Optical Burst Switching Networks for Different Signaling Protocols are separated according to their type and scheduled for appropriate bursts. Third, the edge node generates and transits BHPs. Finally, each burst is transitted according to scheduled transission tie. The general architecture of a sart optical burst switching network is shown in Figure. 1. The OBS network core is created by core nodes interconnected according to a esh or circular topology. Edge nodes are located at the periphery of the OBS network and allow interaction with local access networks, as shown in Figure. 1. IP access network IP access network Bursts creating BHPs generation Sending BHPs and bursts IP access network Edge node A Optical channel BHPs analysis IP routing Bursts all-optical switching OBS network Core nodes IP access network Virtual channel BHP is transitted ahead of burst, having enough tie to open virtual channel Burst is transitted quickly without delay in each node, catching up BHP in destination node Edge node B IP access network BHPs analysis Bursts reception Scheduling and distributing of IP packets in access network Figure 1. General architecture and data transission in sart optical burst switching network In an OBS network, data channels are separated fro signaling channels to provide target functionality. Signaling channels are used for BHP transission. Note that signaling channels are established between each pair of nodes: either between an edge node and core node or between two core nodes. The core node analyzes BHP to obtain the necessary inforation about incoing bursts. Then, the BHP processing syste in the core node provides the following operations: analyzing QoS requireents for IP packets in target bursts; providing routing to select a virtual channel for burst transission; deterining necessary path for optical switching; calculating necessary burst delay; generating and forwarding the odified BHP to the next node of the virtual channel. BHP is forwarded fro one hop to another, and in the process it provides necessary inforation to create all parts of the transparent virtual channel for successful burst transission. To avoid the overtake of BHP by an optical burst, a burst transission is scheduled after a predefined delay, which depends on BHP processing tie and the nuber of interediate nodes of a virtual channel. This tie is called the offset tie and is calculated as follows: tot nк ( tconv tdec ) tsw t 1 sw n (1) where n к is the nuber of interediate nodes in a virtual channel, t conv is the tie for BHP conversion fro optical to electrical for, t dec is the processing tie required to ake a decision about routing and switching a burst, and t sw is the tie needed to reconfigure an optical switch to create an all-optical path for incoing bursts.

4 Sart Coputing Review, vol. 5, no. 5, October Analysis of signaling protocols for OBS networks To support the effective transission of various traffic types, several signaling protocols were developed for optical burst switch networks. The ai of the signaling protocol is to keep all core nodes infored about upcoing bursts. However, there are soe liitations in signaling protocols due to QoS requireents. In ters of QoS, network traffic can be separated into two ain types: delay sensitive and loss sensitive. The forer allows soe packet loss, but requires very low latency and jitter. In contrast, the latter incurs low packet loss and requires data integrity, while delay is not very iportant. Therefore, two basic signaling approaches, JET and TAW, were developed for delay-sensitive and loss-sensitive traffic, respectively. Tell-and-Wait signaling protocol In the TAW signaling protocol, BHP is transitted through all core nodes to the destination edge node, which ensures a successful establishent of a virtual channel. Afterwards, the destination node sends acknowledgeent packets to the transitter. The burst is transitted after the edge node receives the acknowledgeent packet. This ensures a successful burst transission without channel blocking or losses. The tie delay in the burst transission for the TAW protocol is calculated as follows: TAW aggr OT _ TAW burst fiber i1 n T t t t t, (2) where t OT_TAW is the tie for BHP transission and acknowledgeent of feedback, t aggr is the tie for the aggregation burst of the input IP packets to the edge node, t burst is the tie for a burst transission, and t fiber is the tie for burst propagation in the optical fiber. TAW signaling is used for TCP datagras, which requires guaranteed delivery of e-ail, utorrent, Skype, etc. The TAW protocol diagra is shown in Figure. 2. Figure 2. Tell-and-Wait protocol diagra Theoretical acknowledgeent before burst transissions helps to avoid loss. However, it requires ore tie to create a virtual channel that ay be larger than the packets Tie to Live (TTL), especially when a virtual channel consists of any hops. In such cases, soe packets ay be lost before transission, which in turn decreases the perforance of the OBS network.

5 382 Klyash et. al: Perforance Analysis of Sart Optical Burst Switching Networks for Different Signaling Just Enough Tie signaling protocol Protocols In the JET protocol, BHP is transitted through a virtual channel to the destination node. Unlike TAW, the destination node does not send an acknowledgeent packet to the transitter. In this case, the establishent of a virtual channel is not ensured because the transitter does not have inforation about the successful transission of a BHP. A burst transission is scheduled after a pre-defined delay tie. In such cases, bursts can be lost due to blocking in the core nodes. The tie delay of burst transission for the JET protocol is calculated as follows: T t t t t JET aggr OT _ JET burst fiber i1 n, (3) where t OT_JET is the tie required for a BHP transission to reach the end node. The JET protocol is optially suited for UDP ultiedia traffic when the iniu tie delay is ore iportant than guaranteed delivery. A JET protocol diagra is shown in Figure. 2. Figure 3. JET protocol diagra Interediate Node Initiation signaling protocol Interediate Node Initiation is an alternative solution that cobines the advantages of both the TAW and JET ethods and can be adjusted for different traffic requireents. The ain feature of the INI signaling protocol lies in the selection of interediate nodes. In this case, a network is divided into two doains: fro edge node to interediate node and fro interediate node to destination node. In the first doain, signaling is provided according to the TAW protocol, where an interediate node sends an acknowledgeent packet to the transitter. In the second doain, signaling is provided according to the JET protocol. The interediate node is selected according to the criteria of blocking probability. In this case, acknowledgeent is used until the probability of blocking becoes high. Later, interediate node acknowledgeent is not used, because the blocking probability is relatively low. The INI protocol diagra is shown in Figure. 4. The blocking probability in each node depends on the nuber of neighboring nodes. To select an appropriate interediate node, a software-defined optical switching approach is used to ensure that QoS requireents will be satisfied [15]. The tie delay of the burst transission for the INI protocol is calculated as follows: INI aggr OT _ INI burst fiber i1 n T t t t t, (4) where t OT_INI is the tie of the BHP transission and feedback acknowledgeent. The INI signaling protocol is able to adapt at the given traffic requireents.

6 Sart Coputing Review, vol. 5, no. 5, October Figure 4. INI protocol diagra Analysis of burst blocking probability Let s consider the case when all core nodes are without buffers. In this case, burst losses ay occur if all optical paths are occupied by existing burst transissions. In this case, the blocking probability for each channel can be calculated as follows: n P! Pb 1, (5) n! where Р is the the probability of data transission between a pair of nodes (equal for all parts); n is the nuber of input nodes, and is the nuber of output nodes. Note that n in order to avoid blocking in the node. If wavelength converters are not used, then n is the nuber of ultiplexers and is the nuber of deultiplexers, respectively. When wavelength converters are used, n and are equal to the product of the nuber of wavelengths in the fiber, which is equal to the nuber of ultiplexers and deultiplexers, respectively. Let us suppose that n equals. In this case Equation 5 is siplified as follows: Pb 1! P, (6) In Equation 6, we can easily see that P b tends to one as increases. In this situation, buffering is necessary. When the queue is processed according to the First Input First Output (FIFO) odel, the probability of loss depends on buffer size when n=: k Pb P C ki k 1, (7) where i is the nuber of optical buffers. Considering that the probabilities of data transission between the pair of nodes are identical, we assue P=1/, and Equation 7 becoes: k 1 C ki Pb, (8) Based on Equation 8, we show the 3D-plot of the loss probability as a function of nuber of buffers and nuber of wavelength channels (Figure. 5). As shown in Figure. 5, the probability of loss decreases as the nuber of buffers increases. We have deterined that if the nuber of buffers are ore than 5, the probability of loss tends to zero regardless of. Therefore, for OBS networks it is enough to have 5 optical buffers for each core node. Each buffer is ipleented as a fiber delay line (FDL) of specific length, into which bursts are switched to achieve target delay. k

7 384 Klyash et. al: Perforance Analysis of Sart Optical Burst Switching Networks for Different Signaling Protocols (a) (b) Figure 5. 3D (a) plot of burst loss probability, which depends on the nuber of buffers and nuber of wavelengths, and (b) 2D-plot of burst loss probability, which depends on the nuber of buffers Analysis of burst tiing and loss in OBS networks The ai of a signaling protocol is to coordinate burst scheduling in each switching node. Correct scheduling ensures that all bursts, which arrive siultaneously, are properly switched to necessary paths without blocking. Wrong scheduling results lead to inevitable blocking and burst loss. Therefore, BHP always contains inforation about burst arrival tie in order to support correct scheduling in core nodes. Buffers are needed for JET and INI protocols, because in this case the correct establishent of virtual channels is not copletely ensured. Using of buffers requires liitation in the burst axial duration t burst to keep the proper tiing of buffering. The burst delay tie in the buffers is calculated as follows: buff burst between t k t t, (9) where k is the nuber of buffers the burst has to go through, and t between is the tie between two consequent bursts. The burst duration ay change dynaically, but cannot exceed the axiu duration t burst. The inter-burst tie t between is required for a switch reaction to rearrange the paths between the input and output ports, and also to avoid the influence of dispersion, nonlinear effects, and jitter. These influences can increase or decrease the duration of burst transission through fiber. Iportant conditions for switching a burst to the next buffer are: when the previous burst in buffer k outstrips the target burst tie by ore than t between, the target burst ay be switched to the buffer k; when the previous burst in buffer k outstrips the target burst tie by less than t between, the target burst ust be switched to the buffer k+1. Figure. 6 describes possible scenarios where data bursts ay be switched to the buffer or gets lost. Digits in parentheses indicate the nuber of buffers that transit the burst. When the tie delay between the data burst of the fifth buffer and data burst received by edge node is less than t between, burst loss is observed. In cases where soe bursts outstrip previous ones in an optical fiber dynaic, change of the size of the burst ay be the case where soe bursts outperfor previous ones. Consider the scenario when Burst B was switched to Buffer K. It happened because the previous Burst A transitted through Buffer K-1, is ahead less than t between. But Burst C, which coes after Burst B, ay be sent to Buffer K-1. But in this case, the tie between Bursts A and C as well as C and B ust be ore than t between. If Burst C is sall enough, then the next Burst D can be sent to Buffer K-1. And the tie between Bursts C and D, and D and V ust be ore than t between.

8 Sart Coputing Review, vol. 5, no. 5, October When scheduling bursts of different priorities, bursts of saller priority are switched to a buffer with a longer duration, which allows a quicker transission for bursts of higher priority. In this case, the aount of losses related to bursts with saller priorities increases. Since these bursts should be delivered without loss, for the last buffer we suggest additional optoelectronic regenerators. Figure 6. Burst tiing and loss in OBS network with 5 buffers Conclusion This article presents a perforance analysis of different signaling protocols, which are used in optical burst switched networks. Three signaling protocols were studied for different traffic requireents. The TAW protocol provides guaranteed establishent of the virtual channel that is optial for loss-sensitive data flows and for which data integrity is vital. The JET signaling protocol provides quick yet not guaranteed virtual channel establishent that is optial for data flows that are highly sensitive to latency and jitter. The alternative solution is the INI signaling protocol, which cobines both approaches and can be adjusted either to the TAW or to JET protocols. To assess the perforance of an optical burst switch network, we analyze the blocking probability in the core nodes for different nubers of wavelengths and optical buffers. The nuber of optial buffers and scheduling conditions for each burst were deterined. We also analyze and take into account the proble of bursts outstripping to deterine a proper buffering policy for each burst. For the latter, we consider burst priorities and tie delay between consistent bursts. References [1] M. Jo, T. Maksyyuk, B. Strykhalyuk, C. Cho, Device-to-Device Based Heterogeneous Radio Access Network Architecture for Mobile Cloud Coputing, IEEE Wireless Counications, vol. 12, no. 3, pp , Jun Article (CrossRef Link) [2] M. Jo, T. Maksyyuk, R. L. Batista, T. F. Maciel, A. L.F. de Aleida,, M. Klyash, A Survey of Converging Solutions for Heterogeneous Mobile Networks, IEEE Wireless Counications, vol. 21, no. 8, pp , Dec

9 386 Klyash et. al: Perforance Analysis of Sart Optical Burst Switching Networks for Different Signaling Protocols [3] D.M. Maro, M. Blau, Switching solutions for WDM-SDM optical networks, IEEE Counications, vol. 53, no. 2, pp , Feb Article (CrossRef Link) [4] L. Xu, H.G. Perros, G. Rouskas, Techniques for optical packet switching and optical burst switching, IEEE Counications Magazine, vol. 39, no. 1, pp , Article (CrossRef Link) [5] S. Dixit. IP over WDM: building the next-generation optical internet, John Wiley & Sons, [6] Y. Chen, C. Qiao, X. Yu, Optical burst switching: a new area in optical networking research, IEEE Network, vol. 18, no. 3, pp , Article (CrossRef Link) [7] D. Klonidis, F. Cugini, O. Gerstel, M. Jinno, V. Lopez, E. Palkopoulou, M. Sekiya, D. Siracusa, G. Thouenon, C. Betoule, Spectrally and spatially flexible optical network planning and operations, IEEE Counications Magazine, vol. 53, no. 2, pp , Feb Article (CrossRef Link) [8] S. Duych, P. Guskov, T. Maksyyuk, M. Klyash, Siulation of characteristics of optical burst switched networks, In Proc. IEEE International Conference on Microwave & Telecounication technology (CriMiCo 2013), pp , Sep [9] K. Dolzer, C. Gauger, On burst assebly in optical burst switching networks a perforance evaluation of Just- Enough-Tie, In Proceedings of ITC 18, pp , Sep Article (CrossRef Link) [10] S. Duych, T. Maksyyuk, P. Guskov, Siulation of Burst Aggregation and Signaling schees for Optical Burst Switched Networks, Int. Conf. Coputer Science and Engineering, Lviv Polytechnic National Univ., Ukraine, pp.40-41, Nov [11] V. M. Vokkarane, J. P. Jue, Prioritized burst segentation and coposite burst-assebly techniques for QoS support in optical burst-switched networks, IEEE Journal on Selected Areas in Counications, vol. 21, no. 7, pp , Article (CrossRef Link) [12] T. Maksyyuk, S. Duych, O. Krasko, M. Kaidan, B. Strykhalyuk, Study and Developent of Next-Generation Optical Networks, Sart Coputing Review, vol. 4, no. 6, pp , Dec Article (CrossRef Link) [13] S. Duych, T. Maksyyuk, O. Krasko, P. Guskov, The Virtual Channel Paraeters Calculation in All-Optical Network. In Proc. IEEE International Conference on The Experience of Designing and Application of CAD Systes in Microelectronics, (CADSM 2013), pp. 88, Feb [14] K. Lu, J. P. Jue, G. Xiao, I. Chlatac, T. Ozugur, Interediate-Node Initiated Reservation (IIR): A New Signaling Schee for Wavelength-Routed Networks, IEEE Journal on Selected Areas in Counications, vol.21, no. 8, pp , Oct [15] T. Maksyyuk, S. Duych, O. Krasko, M. Jo, Software defined optical switching for cloud coputing transport systes, ACM International Conference on Ubiquitous Inforation Manageent and Counication (IMCOM 2015), No. 46, Jan Article (CrossRef Link) Mykhailo Klyash received his DSc degree in telecounication systes and networks, Odessa National Acadey of Telecounication naed after A.S. Popov, Ukraine in 2007, and his PhD in optical data transission, location, and processing systes, Bonch-Bruevich Saint- Petersburg State University of Telecounications, Saint Petersburg, Russia, in Currently, he is Head of the Telecounication Departent at Lviv Polytechnic National University, Ukraine. His current research interests include distributed networks, cloud coputing, convergent obile networks, big data, software-defined networks, and 5G wireless networks. Mykola Kaidan received his PhD in optoelectronics fro Lviv Polytechnic National University, Ukraine in 2006, and his MS in optoelectronics fro Lviv State University naed after Ivan Franko in He is currently doing a post-doctoral study on telecounication systes and networks at Lviv Polytechnic National University, Ukraine. He is a docent with the Telecounication Departent of Lviv Polytechnic National University. His current research interests include optical networks, photonic optical fibers, non-linear fiber optic, and optical network coponents.

10 Sart Coputing Review, vol. 5, no. 5, October Stepan Duych received his BS and MS in radio physics fro Ivan Franko National University of Lviv, Ukraine, in 2004 and 2006, respectively. He is currently a senior teacher with the Telecounication departent of Lviv Polytechnic National University. His research interests include the design and synthesis of icroprocessor systes, FPGA, and optical burst switching. Copyrights 2015 KAIS