This document discusses challenges and research directions in optical burst switching (OBS) networks. It provides background on OBS architecture, including burst assembly, routing, traffic distribution, scheduling, and signaling protocols. Contention resolution strategies in OBS like optical buffering, wavelength conversion, burst deflection routing, and burst segmentation are also covered. Key challenges discussed include implementing burst segmentation in practical systems, such as dealing with switching time and segment boundary detection. Other challenges are the limited buffering capabilities of optical networks and noise introduced by wavelength conversion. The document also notes issues like shadow contention that can occur with certain contention resolution strategies.
OBS network is a optical communication network.
Data is transported in variable sized units called Bursts.
Dynamic nature leads to high network adaptability and scalability.
Promising solution for all optical network.
Overcomes the complexity of OPS & OCS.
Abstract In optical circuit switching the high values of blocking probability is resolved by dynamic wavelength routing algorithms with wavelength conversion. The aim of this paper is to study these algorithms. Then the algorithm is selected which gives good results with and without wavelength conversion. The selected algorithm is then checked for other parameters of networking namely throughput, packet delivery ratio, and delay. A comparative study is then carried out for increasing traffic. We try to prove that these algorithms satisfy the criteria of QoS parameters by this comparative study. The results of simulation show that the parameters follow the trend of blocking probability of the selected algorithm. Keywords: optical burst switching, throughput, packet delivery ratio, delay.
OBS network is a optical communication network.
Data is transported in variable sized units called Bursts.
Dynamic nature leads to high network adaptability and scalability.
Promising solution for all optical network.
Overcomes the complexity of OPS & OCS.
Abstract In optical circuit switching the high values of blocking probability is resolved by dynamic wavelength routing algorithms with wavelength conversion. The aim of this paper is to study these algorithms. Then the algorithm is selected which gives good results with and without wavelength conversion. The selected algorithm is then checked for other parameters of networking namely throughput, packet delivery ratio, and delay. A comparative study is then carried out for increasing traffic. We try to prove that these algorithms satisfy the criteria of QoS parameters by this comparative study. The results of simulation show that the parameters follow the trend of blocking probability of the selected algorithm. Keywords: optical burst switching, throughput, packet delivery ratio, delay.
Dynamic fragmentation using path exchange scheme in EONmanishajagtap1
In EON(elastic optical system), fragmentation of lightpath is one primary concern. A few methodologies have been introduced. The paths (i.e. Backup and Primary) available for EON. This liberates the lightpaths to be partitioned into parts are induced by primary lightpaths, which are not to be disturbed to accomplish hitless defragmentation. We trade path function work by flipping the ways. This permits lightpaths to be reallocated amid the defragmentation procedure while they function as backup. For changing path function, we show static spectrum reallocation optimization that overcomes spectrum fragmentation.
Design High Performance Combinational Circuits Using Output Prediction Logic-...IOSRJECE
With the continuously increasing demand for low power & high speed VLSI circuits the brain storming among the scientists, inventors & researchers to find the techniques required to design such high performance circuits is also increasing day by day. In the answer to this search several design techniques have been found. Output prediction logic-OPL technique is one of such newly introduced techniques. OPL is a technique that can be applied to conventional CMOS logic families in order to obtain considerable speedups. Speedups of two to three times over static CMOS logic are demonstrated for a variety of combinational circuits. When applied to static CMOS the OPL retains the restoring nature of underlying logic family. In case of OPL applied to the pseudo NMOS & domino logic, the problem of excessive power dissipation is solved & speedups more than static CMOS logic is obtained
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Problems encountered in Routing Algorithms for 2D-Mesh NoCsSandeep Singh
As technology scales down toward deep submicron,
large numbers of IP blocks are being integrated on the same Silicon die, thereby enabling large amount of parallel
computations, such as those required for multimedia workloads.
Network-on-chip (NOC) serves as an important agent to
eliminate the communication bottleneck of future multicore
systems. Arbiter, a prime component has a great impact on the
feasibility of router. In this paper, we concentrate our ideas on
the basic arbitration techniques with their features and found
some problems with their roles in improving the performance of
the routers and finally extending our range to a novel notion of
overcoming extensive problems of starvation, HOL, congestion,
etc. in a novel and feasible manners with a combination of the
existing arbitration techniques in a more compact and sequential
form.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Incorporate ACO routing algorithm and mobile sink in wireless sensor networks IJECEIAES
Today, science and technology is developing, particularly the internet of things (IoT), there is an increasing demand in the sensor field to serve the requirements of individuals within modern life. Wireless sensor networks (WSNs) was created to assist us to modernize our lives, saving labor, avoid dangers, and that bring high efficiency at work. There are many various routing protocols accustomed to increase the ability efficiency and network lifetime. However, network systems with one settled sink frequently endure from a hot spots issue since hubs close sinks take a lot of vitality to forward information amid the transmission method. In this paper, the authors proposed combining the colony optimization algorithm ant colony optimization (ACO) routing algorithm and mobile sink to deal with that drawback and extend the network life. The simulation results on MATLAB show that the proposed protocol has far better performance than studies within the same field.
Energy Aware Routing Protocol for Energy Constrained Mobile Ad-hoc Networks IJECEIAES
Dynamic topology change and decentralized makes routing a challenging task in mobile ad hoc network. Energy efficient routing is the most challenging task in MANET due to limited energy of mobile nodes. Limited power of batteries typically use in MANET, and this is not easy to change or replace while running communication. Network disorder can occur for many factors but in middle of these factors deficiency of energy is the most significant one for causing broken links and early partition of the network. Evenly distribution of power between nodes could enhance the lifetime of the network, which leads to improving overall network transmission and minimizes the connection request. To discourse this issue, we propose an Energy Aware Routing Protocol (EARP) which considers node energy in route searching process and chooses nodes with higher energy levels. The EARP aim is to establish t he shortest route from source to destination that contains energy efficient nodes. The performance of EARP is evaluated in terms of packet delivery ratio, network lifetime, end-to-end delay and throughput. Results of simulation done by using NS2 network simulator shows that EARP can achieve both high throughput and delivery ratio, whereas increase network lifetime and decreases end-to-end delay.
Performance of Non-Uniform Duty-Cycled ContikiMAC in Wireless Sensor Networks IJECEIAES
Wireless Sensor Network (WSN) is a promising technology in Internet of Things (IoTs) because it can be implemented in many applications. However, a main drawback of WSN is it has limited energy because each sensor node is powered using batteries. Therefore, duty-cycle mechanisms are introduced to reduce power consumption of the sensor nodes by ensuring the sensor nodes in the sleep mode almost of the time in order to prolong the network lifetime. One of the de-facto standard of duty-cycle mechanism in WSN is ContikiMAC, which is the default duty-cycle mechanism in Contiki OS. ContikiMAC ensures nodes can participate in network communication yet keep it in sleep mode for roughly 99\% of the time. However, it is found that the ContikiMAC does not perform well in dynamic network conditions. In a bursty network, ContikiMAC provides a poor performance in term of packet delivery ratio, which is caused by congestion. One possible solution is ContikiMAC should increase its duty-cycle rate in order to support the bursty traffic. This solution creates a non-uniform duty-cycle rates among the sensor nodes in the network. This work aims to investigate the effect of non-uniform duty-cycle rates on the performance on ContikiMAC. Cooja simulator is selected as the simulation tool. Three different simulation scenarios are considered depending on the Clear Channel Assessment Rate (CCR) configurations: a low uniform CCR value (Low-CCR), a high uniform CCR value (High-CCR) and non-uniform CCR values (Non-uniform-CCR). The simulation results show that the Low-CCR scenario provides the worst performance of PDR. On the other hand, the High-CCR scenario provides the best performance of PDR. The Non-uniform-CCR provides PDR in between of Low-CCR and High-CCR.
For further details contact:
N.RAJASEKARAN B.E M.S 9841091117,9840103301.
IMPULSE TECHNOLOGIES,
Old No 251, New No 304,
2nd Floor,
Arcot road ,
Vadapalani ,
Chennai-26.
MMINIMUM RESOURCE CONSUMPTIONS ROUTING FOR OPTICAL NETWORKSprj_publication
The problem of determining primary and backup paths for survivable optical WDM
networks is considered. Results of various available routing techniques that try to minimize
the combined cost of primary and the backup path are analyzed for the effects on network
parameters such as mean load, variance of the load on route, number of converters required
by the route and the length of the route. The route cost is modelled such a way that it is
extensible to include any new parameter and vary their relative importance. The efficiency of
such wavelength routed networks has been proved to improve for certain parameters, such as
reduction in blocking probability and number of converters required for desired performance.
The routing is enhanced to analyse effect on network parameters for all node full range
converters, limited number full converters, reserved primary and back up wavelengths and
with no such reservation.
In wireless sensor network energy cutback is considered as a principle intensive challenge which is studied largely in the Wireless Sensor Networks (WSN) literature. Wireless Sensor Networks (WSNs) are pertinent in numerous arenas where WSNs may be used for sensing, ciphering, and communication elements that give a user or administrator the ability to instrument, observe, and retort to events and phenomena in a specific environment. But sensor devices are resource curbed, positioned in an open and unattended environment, different types of attacks and conventional techniques against these attacks are not desirable due to the resource constrained nature of these kinds of networks. An energy-balanced routing method based on forward-aware factor (FAF-EBRM) in which the next-hop node is elected according to the awareness of link weight and forward energy density. FAF-EBRM is compared with Ladder Diffusion Algorithm, which balances the energy utilization, sustain the function era and guarantees high QoS of WSN. The FAF-EBRM is proposed with Secure Routing Layer (SRL) Protocol which ensures that the secure data transmission is achieved without releasing private sensor readings and without introducing significant overhead on the battery-limited sensors.
An Improved Energy Efficient Wireless Sensor Networks Through Clustering In C...Editor IJCATR
One of the major reason for performance degradation in Wireless sensor network is the overhead due to control packet and packet delivery degradation. Clustering in cross layer network operation is an efficient way manage control packet overhead and which ultimately improve the lifetime of a network. All these overheads are crucial in a scalable networks. But the clustering always suffer from the cluster head failure which need to be solved effectively in a large network. As the focus is to improve the average lifetime of sensor network the cluster head is selected based on the battery life of nodes. The cross-layer operation model optimize the overheads in multiple layer and ultimately the use of clustering will reduce the major overheads identified and their by the energy consumption and throughput of wireless sensor network is improved. The proposed model operates on two layers of network ie., Network Layer and Transport Layer and Clustering is applied in the network layer . The simulation result shows that the integration of two layers reduces the energy consumption and increases the throughput of the wireless sensor networks.
Learn about various technology trends that will take us beyond 2014 and into the future. This includes various crowd funding campaigns, the internet of things, and wearable technology.
Dynamic fragmentation using path exchange scheme in EONmanishajagtap1
In EON(elastic optical system), fragmentation of lightpath is one primary concern. A few methodologies have been introduced. The paths (i.e. Backup and Primary) available for EON. This liberates the lightpaths to be partitioned into parts are induced by primary lightpaths, which are not to be disturbed to accomplish hitless defragmentation. We trade path function work by flipping the ways. This permits lightpaths to be reallocated amid the defragmentation procedure while they function as backup. For changing path function, we show static spectrum reallocation optimization that overcomes spectrum fragmentation.
Design High Performance Combinational Circuits Using Output Prediction Logic-...IOSRJECE
With the continuously increasing demand for low power & high speed VLSI circuits the brain storming among the scientists, inventors & researchers to find the techniques required to design such high performance circuits is also increasing day by day. In the answer to this search several design techniques have been found. Output prediction logic-OPL technique is one of such newly introduced techniques. OPL is a technique that can be applied to conventional CMOS logic families in order to obtain considerable speedups. Speedups of two to three times over static CMOS logic are demonstrated for a variety of combinational circuits. When applied to static CMOS the OPL retains the restoring nature of underlying logic family. In case of OPL applied to the pseudo NMOS & domino logic, the problem of excessive power dissipation is solved & speedups more than static CMOS logic is obtained
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Problems encountered in Routing Algorithms for 2D-Mesh NoCsSandeep Singh
As technology scales down toward deep submicron,
large numbers of IP blocks are being integrated on the same Silicon die, thereby enabling large amount of parallel
computations, such as those required for multimedia workloads.
Network-on-chip (NOC) serves as an important agent to
eliminate the communication bottleneck of future multicore
systems. Arbiter, a prime component has a great impact on the
feasibility of router. In this paper, we concentrate our ideas on
the basic arbitration techniques with their features and found
some problems with their roles in improving the performance of
the routers and finally extending our range to a novel notion of
overcoming extensive problems of starvation, HOL, congestion,
etc. in a novel and feasible manners with a combination of the
existing arbitration techniques in a more compact and sequential
form.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Incorporate ACO routing algorithm and mobile sink in wireless sensor networks IJECEIAES
Today, science and technology is developing, particularly the internet of things (IoT), there is an increasing demand in the sensor field to serve the requirements of individuals within modern life. Wireless sensor networks (WSNs) was created to assist us to modernize our lives, saving labor, avoid dangers, and that bring high efficiency at work. There are many various routing protocols accustomed to increase the ability efficiency and network lifetime. However, network systems with one settled sink frequently endure from a hot spots issue since hubs close sinks take a lot of vitality to forward information amid the transmission method. In this paper, the authors proposed combining the colony optimization algorithm ant colony optimization (ACO) routing algorithm and mobile sink to deal with that drawback and extend the network life. The simulation results on MATLAB show that the proposed protocol has far better performance than studies within the same field.
Energy Aware Routing Protocol for Energy Constrained Mobile Ad-hoc Networks IJECEIAES
Dynamic topology change and decentralized makes routing a challenging task in mobile ad hoc network. Energy efficient routing is the most challenging task in MANET due to limited energy of mobile nodes. Limited power of batteries typically use in MANET, and this is not easy to change or replace while running communication. Network disorder can occur for many factors but in middle of these factors deficiency of energy is the most significant one for causing broken links and early partition of the network. Evenly distribution of power between nodes could enhance the lifetime of the network, which leads to improving overall network transmission and minimizes the connection request. To discourse this issue, we propose an Energy Aware Routing Protocol (EARP) which considers node energy in route searching process and chooses nodes with higher energy levels. The EARP aim is to establish t he shortest route from source to destination that contains energy efficient nodes. The performance of EARP is evaluated in terms of packet delivery ratio, network lifetime, end-to-end delay and throughput. Results of simulation done by using NS2 network simulator shows that EARP can achieve both high throughput and delivery ratio, whereas increase network lifetime and decreases end-to-end delay.
Performance of Non-Uniform Duty-Cycled ContikiMAC in Wireless Sensor Networks IJECEIAES
Wireless Sensor Network (WSN) is a promising technology in Internet of Things (IoTs) because it can be implemented in many applications. However, a main drawback of WSN is it has limited energy because each sensor node is powered using batteries. Therefore, duty-cycle mechanisms are introduced to reduce power consumption of the sensor nodes by ensuring the sensor nodes in the sleep mode almost of the time in order to prolong the network lifetime. One of the de-facto standard of duty-cycle mechanism in WSN is ContikiMAC, which is the default duty-cycle mechanism in Contiki OS. ContikiMAC ensures nodes can participate in network communication yet keep it in sleep mode for roughly 99\% of the time. However, it is found that the ContikiMAC does not perform well in dynamic network conditions. In a bursty network, ContikiMAC provides a poor performance in term of packet delivery ratio, which is caused by congestion. One possible solution is ContikiMAC should increase its duty-cycle rate in order to support the bursty traffic. This solution creates a non-uniform duty-cycle rates among the sensor nodes in the network. This work aims to investigate the effect of non-uniform duty-cycle rates on the performance on ContikiMAC. Cooja simulator is selected as the simulation tool. Three different simulation scenarios are considered depending on the Clear Channel Assessment Rate (CCR) configurations: a low uniform CCR value (Low-CCR), a high uniform CCR value (High-CCR) and non-uniform CCR values (Non-uniform-CCR). The simulation results show that the Low-CCR scenario provides the worst performance of PDR. On the other hand, the High-CCR scenario provides the best performance of PDR. The Non-uniform-CCR provides PDR in between of Low-CCR and High-CCR.
For further details contact:
N.RAJASEKARAN B.E M.S 9841091117,9840103301.
IMPULSE TECHNOLOGIES,
Old No 251, New No 304,
2nd Floor,
Arcot road ,
Vadapalani ,
Chennai-26.
MMINIMUM RESOURCE CONSUMPTIONS ROUTING FOR OPTICAL NETWORKSprj_publication
The problem of determining primary and backup paths for survivable optical WDM
networks is considered. Results of various available routing techniques that try to minimize
the combined cost of primary and the backup path are analyzed for the effects on network
parameters such as mean load, variance of the load on route, number of converters required
by the route and the length of the route. The route cost is modelled such a way that it is
extensible to include any new parameter and vary their relative importance. The efficiency of
such wavelength routed networks has been proved to improve for certain parameters, such as
reduction in blocking probability and number of converters required for desired performance.
The routing is enhanced to analyse effect on network parameters for all node full range
converters, limited number full converters, reserved primary and back up wavelengths and
with no such reservation.
In wireless sensor network energy cutback is considered as a principle intensive challenge which is studied largely in the Wireless Sensor Networks (WSN) literature. Wireless Sensor Networks (WSNs) are pertinent in numerous arenas where WSNs may be used for sensing, ciphering, and communication elements that give a user or administrator the ability to instrument, observe, and retort to events and phenomena in a specific environment. But sensor devices are resource curbed, positioned in an open and unattended environment, different types of attacks and conventional techniques against these attacks are not desirable due to the resource constrained nature of these kinds of networks. An energy-balanced routing method based on forward-aware factor (FAF-EBRM) in which the next-hop node is elected according to the awareness of link weight and forward energy density. FAF-EBRM is compared with Ladder Diffusion Algorithm, which balances the energy utilization, sustain the function era and guarantees high QoS of WSN. The FAF-EBRM is proposed with Secure Routing Layer (SRL) Protocol which ensures that the secure data transmission is achieved without releasing private sensor readings and without introducing significant overhead on the battery-limited sensors.
An Improved Energy Efficient Wireless Sensor Networks Through Clustering In C...Editor IJCATR
One of the major reason for performance degradation in Wireless sensor network is the overhead due to control packet and packet delivery degradation. Clustering in cross layer network operation is an efficient way manage control packet overhead and which ultimately improve the lifetime of a network. All these overheads are crucial in a scalable networks. But the clustering always suffer from the cluster head failure which need to be solved effectively in a large network. As the focus is to improve the average lifetime of sensor network the cluster head is selected based on the battery life of nodes. The cross-layer operation model optimize the overheads in multiple layer and ultimately the use of clustering will reduce the major overheads identified and their by the energy consumption and throughput of wireless sensor network is improved. The proposed model operates on two layers of network ie., Network Layer and Transport Layer and Clustering is applied in the network layer . The simulation result shows that the integration of two layers reduces the energy consumption and increases the throughput of the wireless sensor networks.
Learn about various technology trends that will take us beyond 2014 and into the future. This includes various crowd funding campaigns, the internet of things, and wearable technology.
1.What is IP address
2.When & how it was devised
3.IPV4 Features & its functionality
4.Benefits of IPV4 & Devices supporting IPV4
5.Problems of IPV4 & What happened to IPV5
6.What led to IPV6
7.IPV6 Features & Functionality
8.Benefits of IPV6 & supporting devices
9.How transition from IPV4 to IPV6 will happen
10.Problems & challenges that are anticipated & Conclusion
DYNAMIC CONGESTION CONTROL IN WDM OPTICAL NETWORKcscpconf
This paper is based on Wavelength Division Multiplexing (WDM) optical networking. In this optical networking, prior to data transfer, lightpath establishment between source and
destination nodes is usually carried out through a wavelength reservation protocol. This wavelength is reserved corresponding to a route between the source and destination and the
route is chosen following any standard routing protocol based on shortest path. The backward reservation protocol is implemented initially. A fixed connected and weighted network is
considered. The inputs of this implementation are the fixed network itself and its corresponding shortest path matrix. After this initial level of implementation, the average node usage over a time period is calculated and various thresholds for node usage are considered. Above threshold value, request arriving at that path selects its next shortest path. This concept is
implemented on various wavelengths. The output represents the performance issues of dynamic congestion control.
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
Abstract : As the network size increases the probability of congestion occurrence at nodes increases. This is because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses. In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing (IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput and packet delivery fraction. Keywords- DSDV, Hybrid protocol, AODV, IAODV, MANET
Congestion Control in Manets Using Hybrid Routing ProtocolIOSR Journals
As the network size increases the probability of congestion occurrence at nodes increases. This is
because of the event driven nature of ad hoc networks that leads to unpredictable network load. As a result
congestion may occur at the nodes which receive more data than that can be forwarded and cause packet losses.
In this paper we propose a hybrid scheme that attempts to avoid packet loss due to congestion as well as reduce
end to end delay in delivering data packets by combining two protocols- Destination sequenced distance vector
routing (DSDV), which is a table driven or proactive protocol and Improved Ad-hoc on demand vector routing
(IAODV) which is an on-demand or reactive protocol that reduces packet loss due to congestion. The strategy
adopted is use DSDV for path selection and if congestion occurs than switch over to IAODV. The routing
performance of this model is then compared with IAODV and DSDV in terms of end to end delay, throughput
and packet delivery fraction
Fault Tolerant Congestion based Algorithms in OBS NetworkCSCJournals
In Optical Burst Switched networks, each light path carry huge amount of traffic, path failures may damage the user application. Hence fault-tolerance becomes an important issue on these networks. Blocking probability is a key index of quality of service in Optical Burst Switched (OBS) network. The Erlang formula has been used extensively in the traffic engineering of optical communication to calculate the blocking probability. The paper revisits burst contention resolution problems in OBS networks. When the network is overloaded, no contention resolution scheme would effectively avoid the collision and cause blocking. It is important to first decide, a good routing algorithm and then to choose a wavelength assignment scheme. In this paper we have developed two algorithms, Fault Tolerant Optimized Blocking Algorithm (FTOBA) and Fault Tolerant Least Congestion Algorithm (FTLCA) and then compare the performance of these algorithms on the basis of blocking probability. These algorithms are based upon the congestion on path in OBS network and based on the simulation results, we shows that the reliable and fault tolerant routing algorithms reduces the blocking probability.
Quadrant Based DIR in CWin Adaptation Mechanism for Multihop Wireless NetworkIJCI JOURNAL
In Multihop Wireless Networks, traffic forwarding capability of each node varies according to its level of contention. Each node can yield its channel access opportunity to its neighbouring nodes, so that all the nodes can evenly share the channel and have similar forwarding capability. In this manner the wireless channel is utilized effectively, which is achieved using Contention Window Adaptation Mechanism (CWAM). This mechanism achieves a higher end-to-end throughout but consumes the network power to a higher level. So, a newly proposed algorithm Quadrant- Based Directional Routing Protocol (Q-DIR) is implemented as a cross-layer with CWAM, to reduce the total network power consumption through limited flooding and also reduce the routing overheads, which eventually increases overall network throughput. This algorithm limits the broadcast region to a quadrant where the source node and the destination nodes are located. Implementation of the algorithm is done in Linux based NS-2 simulator
Design A Congestion Aware Routing Algorithm for Synchronous Cam Designijtsrd
The effect of process variation (PV) on delay is a major reason to decay the performance in advanced technologies. The performance of front routing algorithms is determined with or without PV for different traffic patterns. The saturation throughput and average message delay are used as performance metrics to evaluate the throughput. PV decreases the saturation throughput and increases the average message delay. Adaptive routing algorithm should be manipulated with the PV. A novel PV delay and congestion aware routing (PDCR) algorithm is presented for asynchronous network-on-chip (NOC) design. The routing algorithm performs various adaptive routing algorithms in the average delay and saturation throughput for different traffic patterns. A low-power content-addressable memory (CAM) by a new algorithm is proposed for associativity between the input tag and the corresponding address of the output data. The proposed architecture is depends on a recently developed sparse clustered network by utilizing binary connections that on-average eliminates most of the parallel comparisons performed during a search. P. Mounica | R. Umamaheswari | R. Madhavi | R. Nischala | N. Ramesh Babu"Design A Congestion Aware Routing Algorithm for Synchronous Cam Design" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: http://www.ijtsrd.com/papers/ijtsrd11547.pdf http://www.ijtsrd.com/engineering/electronics-and-communication-engineering/11547/design-a-congestion-aware-routing-algorithm-for-synchronous-cam-design/p-mounica
Fuzzy Controller Based Stable Routes with Lifetime Prediction in MANETsCSCJournals
In ad hoc networks, the nodes are dynamically and arbitrary located in a manner that the interconnections between nodes are changing frequently. Thus, designing an effective routing protocol is a critical issue. In this paper, we propose a fuzzy based routing method that selects the most stable route (FSRS) considering the number of intermediate nodes, packet queue occupancy, and internodes distances. Also it takes the produced cost of the selected route as an input to another fuzzy controller predicts its lifetime (FRLP), the evaluation of the proposed method is performed using OMNet++4.0 simulator in terms of packet delivery ratio, average end-to-end delay and normalized routing load.
A comparative study in wireless sensor networksijwmn
Sensor networks consist of a large number of small, low-powered wireless nodes with limited computation,
communication, and sensing abilities, in a battery-powered sensor network, energy and communication
bandwidth are a precious resources. Thus, there is a need to adapt the networking process to match the
application in order to minimize the resources consumed and extend the life of the network. In this paper,
we introduce a comparative study in different routing algorithms that propose vital solutions to the most
important issues that should be taken into account when designing wireless network which are reliability,
lifetime, communication bandwidth, transmission rand, and finally the limited energy issue, so we will
introduce their algorithms and discuss how did they propose to solve such of these challenges and finally
we will do some evaluation to each approach.
Nearest Adjacent Node Discovery Scheme for Routing Protocol in Wireless Senso...IOSR Journals
The broad significance of Wireless Sensor Networks is in most emergency and disaster rescue
domain. The routing process is the main challenges in the wireless sensor network due to lack of physical links.
The objective of routing is to find optimum path which is used to transferring packets from source node to
destination node. Routing should generate feasible routes between nodes and send traffic along the selected path
and also achieve high performance. This paper presents a nearest adjacent node scheme based on shortest path
routing algorithm. It is plays an important role in energy conservation. It finds the best location of nearest
adjacent nodes by involving the least number of nodes in transmission of data and set large number of nodes to
sleep in idle mode. Based on simulation result we shows the significant improvement in energy saving and
enhance the life of the network
Fuzzy Route Switching for Energy Preservation(FEP) in Ad Hoc NetworksA. Sufian
Nodes in ad hoc networks have limited battery power. Hence they require energy-efficient technique to improve average
network performance. Maintaining energy-efficiency in ad hoc networks is really challenging because highest energyefficiency
is achieved if all the nodes are always switched off and energy-efficiency will be minimum if all the nodes are
fully operational i.e. always turned-on. Energy preservation requires redirection of data packets through some other routes
having good performance. This improves data packet delivery ratio and number of alive nodes decreasing cost of messages.
International Journal of Pharmaceutical Science Invention (IJPSI)inventionjournals
International Journal of Pharmaceutical Science Invention (IJPSI) is an international journal intended for professionals and researchers in all fields of Pahrmaceutical Science. IJPSI publishes research articles and reviews within the whole field Pharmacy and Pharmaceutical Science, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Improved routing scheme with ACO in WSN in comparison to DSDVijsrd.com
Routing is the process of selecting best paths in a network in terms of energy and distance. In adhoc it is critical to collect the information in an efficient manner as it has limitations in terms of centralized congestion. In such case to perform the effective communication there is the requirement of some such routing approach that can provide the routing with optimized path. In this work, ACO based routing approach is defined to generate the optimized path in comparison to DSDV over the network. The presented approach is implemented in matlab environment and obtained results shows the effective results in terms of optimized path.
DEADLOCK RECOVERY TECHNIQUE IN BUS ENHANCED NOC ARCHITECTUREVLSICS Design
Increase in the speed of processors has led to crucial role of communication in the performance of systems. As a result, routing is taken into consideration as one of the most important subjects of the Network on Chip architecture. Routing algorithms to deadlock avoidance prevent packets route completely based on network traffic condition by means of restricting the route of packets. This action leads to less performance especially in non-uniform traffic patterns. On the other hand True Fully Adoptive Routing algorithm provides routing of packets completely based on traffic condition. However, deadlock detection and recovery mechanisms are needed to handle deadlocks. Use of global bus beside NoC as a parallel supportive environment, provide platform to offer advantages of both features of bus and NoC. This bus is useful for broadcast and multicast operations, sending delay sensitive signals, system management and other services. In this research, we use this bus as an escaping path for deadlock recovery technique. According to simulation results, this bus is suitable platform for deadlock recovery technique.
Influence of Clustering on the Performance of MobileAd Hoc Networks (MANETs)Narendra Singh Yadav
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Challenges, Issues and Research directions in Optical Burst Switching
1. International Journal of Computer Applications Technology and Research
Volume 2– Issue 2, 131 - 136, 2013
www.ijcat.com 131
Challenges, Issues and Research directions in Optical
Burst Switching
Terrance Frederick Fernandez
Department of Computer
Science and Engineering
Pondicherry Engineering
College
Puducherry, India
Megala.T
Department of Computer
Science and Engineering
Pondicherry Engineering
College
Puducherry, India
Sreenath.N
Department of Computer
Science and Engineering
Pondicherry Engineering
College
Puducherry, India
Abstract: Optical Burst Switching architecture (OBS) is based on buffer-less WDM network that provides unbelievably huge
bandwidth for communication. A brief review on OBS architecture along with its supporting protocols is studied here. This
architecture suffers from various issues and these complications along with the future research directions are reviewed here.
Keywords: Optical Burst Switching, Contention resolution, AON, Routing and Wavelength Assignment, OBS research issues.
1. INTRODUCTION TO OBS
Figure 1. OBS Network Architecture
Optical Switching architecture has become the research focus
[1], [2] in recent years due to the heavy demand in huge
bandwidth and efficient network resource allocation. Three
Optical switching architectures are available and they are
Optical Circuit Switching (OCS), Optical Packet Switching
(OPS) and Optical Burst Switching (OBS). Among these
schemes, OBS [3] combines the merits of mature electronic
process capability and the high-capacity optical transport
capability. Multiple packets that belong to the same egress
node are packed into a single Data Burst (DB) at the ingress
nodes. Control information for this DB is sent ahead on
separate wavelength and is called Burst Header Packet (BHP).
BHPs are processed electronically at each intermediate core
nodes to reserve network resources before the arrival of the
DBs.
1.1 OBS Assembly
The Burst assembly happens at the input node ingress, where
the packets belonging to the same destination are grouped into
a single Burst in order to switch all-optically into the core
nodes.
• Timer based Burst Assembly Mechanism.
• Burst Length (threshold) based Burst Assembly
Mechanism.
• Hybrid/Mixed Burst Assembly Mechanism.
• Composite Burst Assembly Mechanism.
• Optimized/Adaptive Burst Assembly Mechanism.
An assembled burst is sent into the core at periodic/fixed time
intervals while the Data Bursts are of variable lengths for
Timer based Burst Assembly Mechanism [4]. On the contrary,
the burst lengths are fixed and are generated at non-
periodic/variable time intervals for Burst; length-threshold
based Burst Assembly Mechanism [4]. In some special cases,
packets of different classes but belonging to same bursts are
combined. Here, these are placed from head of the burst to the
tail of the bursts in order of decreasing classes and this is
called as composite burst assembly algorithm [4]. In
hybrid/mixed burst assembly mechanism, the bursts are
assembled and sent either if the timer expires or the burst
length is reached [5]. Dynamic adaptive threshold on burst
length is set in order to optimize the overall performance in
OBS for QoS sensitive traffic [5].
1.2 OBS Routing
Types of routing Strategies include
• Proactive/Static routing
• Dynamic congestion-based routing
The Proactive approach is based on adaptive use of multiple
paths between edge nodes. In dynamic congestion based
routing the core nodes in the network gather the load
information on their output links and send feedback to all the
edge nodes, so as to enable the edge nodes to balance the load
and thus routing is done.
There are two subtypes in dynamic congestion-based routing:
• Fixed alternate shortest path dynamic congestion-based
routing
• Least congested dynamic route calculation
The other routing strategies are [6]:
• Distributed routing
• Isolated routing approach
OBS Core
IP
OBS
Ingress
IP
OBS
Egress
TCP Sender
TCP Receiver
2. International Journal of Computer Applications Technology and Research
Volume 2– Issue 2, 131 - 136, 2013
www.ijcat.com 132
Distributed routing algorithm [7] introduces the problem of
inaccuracy in network state information. The routing
decisions performed by this algorithm are optimal as long as
this information perfectly represents the actual network state,
what is impossible to achieve in real network. Moreover,
distributed routing involves additional signalization
complexity so as to exchange the state information inside the
network. The isolated routing approach [7] which performs
the path selection based only on local node/link state
information minimizes problems encountered in isolated
routing algorithm. However, its suboptimal nature since it
only considers the congestion of the current node and its links
may result in worse performance results.
In [8], three different routing algorithms have been
implemented, namely:
• Shortest Path (SP).
• Multi-Path (MP) and
• Bypass (BP).
The SP algorithm is used here as a reference for the later two
algorithms could be classified as isolated adaptive routing
algorithms. SP assigns a route of the shortest distance between
source and destination nodes for each burst. If more than one
such path exists, the first computed is selected. In this case,
only one route is available for a burst. Therefore, if there is a
contention between burst reservations that cannot be resolved
in the frequency and time domains the burst is lost.
In MP algorithms number of paths are pre-established
between each pair of source and destination nodes. The
algorithm makes a routing decision for each individual burst
selecting the shortest path available, i.e. the path that has free
output channel available for resources reservation procedure.
Therefore, the first route that is analyzed is the SP and in case
the burst cannot be transmitted on it the next one of a length
equal or higher is checked. After path selection in source node
the burst follows this path towards the destination node. If the
congestion occurs inside the network the routing algorithm
can reroute the burst to the other path under condition that this
path is originated and terminated in the same pair of nodes as
the burst source and destination nodes. In the evaluation study
we consider that there are 4 paths available between each pair
of source-destination nodes.
BP algorithm assumes that a burst can by-pass congested link
by transmitting it through another node. In particular, if there
are no resources available for burst transmission on specific
output port, the burst is allowed to make one additional hop
through other node with the objective to return to its default
path in the next hop. Regarding the isolated adaptive routing,
the isolated term means that the routing decision is made on
base of local node state information. Likewise, the adaptive
routing term expresses capability to dynamic changes in route
selection in order to perform the best decision. Both
considered isolated adaptive routing takes into account
availability of transmission resources for a given burst on its
default output port. In case, there are not free resources the
algorithm tries to reroute a burst on other path (if it is
available) with other output port according to the routing
strategy, by selecting either one of multiple paths in MP or
bypassing congested link in BP.
Therefore, the goal of the study is to investigate the capability
of pure isolated adaptive routing algorithms to distribute the
traffic and reduce data losses in connection-oriented OBS
networks.
1.3 Traffic Distribution in OBS
Traffic distribution in OBS can be done at the Burst Level
(BL) by making a path selection for each newly incoming
burst at ingress node according to a calculated distribution
probability within a time period. It can also be made at the
Flow Level (FL) by making a path selection for each newly
incoming flow at ingress node according to a calculated
distribution probability within a time period and all bursts
within a particular flow will follow the same path. Balance the
traffic load by shifting incoming bursts along the primary and
secondary paths. Probe the sent packets periodically and sent
through the least congested path. Always aim to minimize
Burst loss and average transfer delay [8].
• Equal Proportion Multipath Routing (EPMR).
• Hop Length Multipath Routing (HLMR).
• Adaptive Alternative Routing Algorithm (AARA).
• Gradient Projection Multipath Routing (GPMR).
GPMR-BL (Burst level) outperforms all. Burst Loss for
GPMR-BL is 20% less than AARA-BL for low traffic loads
and also improves with medium/ high loads. GPMR-BL
converges quickly (with sudden traffic increase). Burst level
probability first decreases and then increases as measurement
time window increases. For small Window size, GPMR-BL
cannot work with inaccurate traffic information. For large
Window size, GPMR cannot adapt to changing traffic load in
networks [15].
1.4 Scheduling in OBS
• Horizon Scheduling.
• Latest Available Unused Channel with Void Filling
(LAUC-VF).
• Minimum Starting Void (MSV).
• Constant Time Burst Resequencing (CTBR)
The latest time at which a channel is currently scheduled
to use is called as a “horizon”. In the horizon scheduling
algorithm, the horizon scheduler selects the channel with
latest horizon from the set of channels whose horizons are less
than burst arrival times. LAUC-VF keeps track of all voids in
a channel and schedule bursts in one of the voids. If more than
one void can fit a burst then the one with latest beginning time
is assigned.MSV uses a geometric approach (binary search
tree) that minimizes the distance between the starting time of
the void and starting time of the burst. CTBR is the “Optimum
Wavelength Scheduler”. Instead to process burst as soon as
the BHP arrive, we delay scheduling of the bursts and process
in order of expected Burst arrival time. BHP is processed not
in its arrival times but at the arrival times of Data bursts. The
link utilization of LAUC-VF is higher than horizon
scheduling but gets slower with huge number of voids.
Table 1. Time Complexity for Scheduling Algorithms
Complexity Scheduling Algorithm
O (log h) Horizon Scheduling
O (log m) Latest available unused channel - Void
filling
O (log m) Minimum Starting Void
O (1) Constant Time Burst Resequencing
1.5 Signaling in OBS
The wavelength reservation algorithm for OBS network
was adopted from “ATM Block Transfer (ABT)”. There are
two versions of ABT and they are [7].ABT with immediate
reservation and ABT with delayed reservation. In the former,
the wavelength is immediately reserved and Data Bursts are
sent on receiving Burst Header. If wavelength cannot be
reserved then the DB is dropped. In the latter, the header and
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Bursts are separated by a period called “Offset Time
(OT)”.Based on the above two versions of ABT, there are
three Burst Reservation schemes in OBS
• Tell And Go (TAG) protocol.
• Just in Time (JIT) protocol.
• Just Enough Time (JET) protocol.
• Horizon.
TAG does immediate reservation with Zero/ minimum
offset. DB is delayed by FDL while CP is processed. Negative
Acknowledgement (NACK) is sent if DB is dropped.JIT does
immediate reservation with Zero/ minimum offset. DBs and
CPs are separated by time slot. In-band Terminator (IBT) at
the end of each DBs to release wavelength.JET does delayed
reservation. CPs and DBs are separated by an “Offset Time
(OT)”. OT corresponds to the number of hops between source
and destination. Delayed reservation is required for OBS
networks, because the travelling speed of the DB is usually
slower than that of the CP. It is because the DB can cut
through the switches without buffering/processing delay
unlike the CP which has that. So, this reservation would deny
the catching up of the DB with its CP. Horizon [12] based on
the knowledge of the latest time at which the channel is
currently scheduled to be in use.
1.6 Contention Resolution in OBS
“Contention” occurs in OBS if two or more incoming
bursts contend for the same output wavelength at the same
link [11]. This contention is to be resolved and is done by
• Optical Buffering.
• Wavelength Conversion.
• Burst Deflection Routing (Alternate Routing).
• Burst Segmentation.
• Burst re-transmission.
• Burst TCP (BTCP) [12].
If a contention occurs at any OBS core node without any of
the above contention schemes or if the degree of contention is
so high and it is not able to tackle the contentions then the
network would opt for a policy called “Dropping Policy
(DP)”. There is an extension of the DP with retransmission
[13], where we may retransmit and drop DBs that have
experienced fewer retransmissions. Buffering in OBS is done
in time domain by the use of the Fiber Delay Lines that limit
the amount of time a burst could reside unlike electronic
buffers, where a packet can stay in the buffer for an undefined
time. Electronic buffers are present at the electronic edge
nodes. Optical technology is immature and buffers are not
invented for optical core nodes. It is impossible to delay the
burst for infinite period of time using Fiber Delay Lines
(FDLs). It is done in “Space domain”. Wavelength
Conversion is the capability of the optical network to convert
an input wavelength to a desired output wavelength. It is done
in spectral/Wavelength domain. It is immature, costly and
produces linear effects such as noise.
Break the assembled data-burst into a number of segments
and the process is called “Segmentation” [14]. “Segments” are
basic transport units [8] and are electronic transport units
invisible in optical domain [15]. There are two segmentation
policies and they are: Head dropping policy and tail dropping
policy. In the former, the head of the contending burst is
dropped. In the latter, the tail of the contending burst is
dropped. In [11], ‘The modified-tail dropping policy’ was
proposed, where the tail of the contending burst is dropped
only if the number of segments in the tail is less than the total
number of segments in the contending burst . On the other
case, the entire contending burst is dropped. This reduces the
probability of a short burst preempting a longer burst and
minimizes the number of packets lost during contention.
Deflection Routing is done in a “Space domain”. If there is a
contention at the preferred link then the burst is forwarded at
any available output. This is also called as “Hot Potato
Routing” [11]. In [8], two different algorithms for contention
resolution are described in frequency and time domains,
namely
• MINLEN that is a Horizon type and
• VF-MM that is a Void-Filling type.
The Horizon algorithms base on the knowledge of the
latest time at which the channel (wavelength) is currently
scheduled to be in use. The MINLEN allocation algorithm
looks for a free channel with a minimum queue, i.e. with the
earliest possible allocation. The Void Filling scheduling
algorithm can make a reservation of free resources even if
they are located between two reservations already done.
Basing on this approach the VF-MM algorithm tries to place a
new reservation in a space of a minimum gap.
2. OBS CHALLENGES
2.1 Burst Segmentation in Practical System
Challenges when implementing burst segmentation in
practical systems were:
• Switching time: Since the system does not implement
buffering or any other delay mechanism, the switching
time is the number of packets lost during reconfiguring
the switch due to contention. Hence, a slower switching
time results in higher packet loss. While deciding which
burst to segment, we consider the remaining length of
the original burst, taking the switching time into
account. By including switching time in burst length
comparisons, we can achieve the optimal output burst
lengths for a given switching time.
• Segment boundary detection: In the optical network,
segment boundaries of the burst are transparent to the
intermediate nodes that switch the burst segments all-
optically. At the network edge nodes, the burst is
received and processed electronically. Since the burst is
made up of many segments, the receiving node must be
able to detect the start of each segment and identify
whether or not the segment is intact. If each segment
consists of an Ethernet frame, detection and
synchronization can be performed using the preamble
field in the Ethernet frame header, while errors and
incomplete frames can be detected by using the CRC
field in the Ethernet frame.
• Trailer creation: The trailer has to be created
electronically at the switch where the contention is
being resolved. The time to create the trailer can be
included in the header processing time, at each node.
2.2 Challenges in Contention Resolution
Strategies
A burst can reside in an optical buffer only for a
specified amount of time unlike electronic buffers.
Wavelength conversion produces linear effects like
‘noise’ and it is costly.
In tail dropping segmentation scheme, the header
contains the total burst length even if the tail is dropped
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[15], and thus downstream nodes are unaware of
truncation. This is called “Shadow Contention”.
In head dropping segmentation scheme, there will be
more out-of-order delivery [15] in contrast to the tail
dropping policy where the sequence is maintained.
Long bursts passing through different switches
experience contention at many switches [15].
Bursts of bigger lengths cannot be stored at the “Fiber
Delay Lines” [7].
Burst deflection routing dynamically deflects the Bursts
in an alternate path due to contention in the primary path
and is usually longer than the primary path. Thus it
increases the propagation delay [5].
The deflected bursts might also loop multiple times
wasting network bandwidth [14].
2.3 TCP over OBS Challenges
It is quite normal to employ OBS as core architecture under
TCP as it constitutes almost 90% of the current internet traffic
and thus when an optical core network, i.e.., Optical Burst
Switching is considered there would be number of challenges
namely:
• OBS experiences Bandwidth Delay Product (BDP) , thus
suffers from speed mismatch with TCP. Even if the TCP
Scaling option is employed to reach congestion window
to 4MB from 64KB longer time would be consumed.
• The Delayed ACK must be used in TCP over OBS as in
reality all TCP segments cannot be included in a single
burst which causes further delay. .
• High Speed TCP (HSTCP) was proposed for high BDP
networks that offers bad throughput for Burst losses.
3. OBS ISSUES
In [13], a TCP over OBS network is considered. The
throughput of various implementations of TCP namely TCP
Tahoe, Reno and New Reno are done. An experimental study
represented results of throughput of TCP source variants,
Tahoe, Reno and New Reno. The network parameters such as,
bandwidth, packet size, congestion window size and queue-
limit were considered for this experiment. The vital issue in
this paper is TCP variants like TCP Vegas, TCP SACK, and
TCP FACK etc.., were not considered. Most cases consider
TCP Westwood over OBS networks.
In [17], a performance evaluation of an OBS router was done.
It was said that OBS with LPI can reduce energy consumption
up to 60% at low loads. A desired scheduler buffer size to
minimize the overall packet blocking probability of OBS was
considered in [18]. A novel label Switched path design for
Generalized MPLS over OBS was modeled in [19].
The Control plane in IP and optical domains are usually
separated. But in [20], a “unified control plane” is made for
end-end service provision. Another contention resolution
technique by proposing new CRT based on control packet
buffering was done in [21]. Mathematical model also been
proved to analyze the performance of OBS network core node
with JIT, buffering is done on electronic node. The Control
Packet that fails reserving required amount of resource were
not dropped immediately, rather electronically buffered for
some threshold time, the time is decided at ingress node
depend on each burst duration. Offset time must be increased
so that to avoid the burst to reach the core node are still not
ready. New quality theory impatience concept was
mathematically driven .JIT is used; slight modification is done
at MAC layer performance enhancing technique.
LPI was proposed by IEEE 802.3az task Force to reduce
energy consumption in network devices. In [22] a Wake
Transition Decision algorithm was proposed to maximize
sleep time thus improving performance. A hybrid Wavelength
Division Multiplexing and Optical Code Division
Multiplexing (WDM/OCDM) scheme is used to mitigate the
blocking probability of OBS networks in [23]. Fiber Delay
Lines are Optical buffers that can tap/delay an optical data for
a finite amount of time and they are costly. An aim to
minimize this issue, OBS Tune and Select (TAS) node
architecture was proposed in [24], where a dedicated
input/output port of the switch is assigned to an FDL shared
between the output ports in a feedback configuration (TAS-
shFDL).
In [25], several alternative TCP protocols were reviewed and
their performance in terms of throughput and fairness were
compared to select the most suitable TCP protocol for end-to-
end Grid data transmission all the proposed methodologies are
demonstrated and evaluated on an actual OBS/WSON testbed
with both control and data planes, allowing the verification of
their feasibility and effectiveness, and obtaining valuable
insights for deploying the proposed solutions into real
consumer Grid networks. However, even though state-of-the-
art techniques are being considered, there are three major
limitations namely Limitation of network infrastructures,
limitation of resource discovery and management Schemes an
limitation of end-to-end transmission control protocols (TCP)
that prevent the wide deployment of the consumer Grid. In
order to address these above 3 issues, an integrated
OBS/wavelength switched optical network (WSON) was
proposed with the assistance of a self-organized resource
discovery and management scheme to support consumer Grid
applications. These proposed solutions are experimentally
demonstrated and evaluated on an actual OBS/WSON testbed.
An experimental demonstration and evaluation of dynamic
provisioning of consumer Grid services by using the
integrated OBS/WSON as a network infrastructure, SRDM
for resource discovery and management, and High-speed TCP
were done.
4. OBS RESEARCH DIRECTIONS
OBS has attracted lot of researchers due to its ability to
achieve dynamic and on-demand bandwidth allocation that
offers improved network economics and enables control and
management integration. Optical Burst Switching is currently
one of the biggest research topics under study and the research
issues in it can be broadly classified into two namely: Security
issues in OBS and QoS issues in OBS. The QoS issues were
discussed in (SECTION 3) and can be sub-categorized based
on two kinds of blocking either QoS issues due to contention
or QoS issues due to Bit Error Rates.
At the industrial level, commercial products were very rarely
made based on OBS and the only company that offers this
product is “Matisse networks” as the technology is still
immature [10]. To model or design an OBS node, there is a
requirement of test beds or simulators. Few of the OBS
simulations were implemented on test beds. These OBS
network test-beds would not be imported to most Asian
countries like India, Sri Lanka, and Pakistan etc. So, these
researchers are forced to a single option namely,
implementing on a simulator. On the other hand, simulators
that are available for Optical Burst Switching do not cater the
entire requirements that are needed to simulate the entirety of
a particular OBS protocol. The survey of various simulators
was done in [26], [27], and [28]. It was inferred that
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[24] Tafani D, McArdle C, Barry, L.P, "Cost Minimization
for Optical Burst Switched Networks with Share-per-
Node Fibre Delay Lines", IEEE Communications Letters.
[25] Lei Liu, Hongxiang Guo, Tsuritani, T et. al., "Dynamic
Provisioning of Self-Organized Consumer Grid Services
Over Integrated OBS/WSON Networks ", Journal of
Lightwave Technology.
[26] Vasco N. G. J. Soares, Iúri D. C. Veiga and Joel J. P. C.
Rodrigues “OBS Simulation Tools: A Comparative
Study”, 2009.
[27] Oscar Pedrola, Sébastien Rumley and Miroslaw
Klinkowski, “Flexible Simulators for OBS Network
Architectures”, International Conference on Transparent
Optical Networks (ICTON), pp. 117-122, 2008.
[28] Joel J. P. C. Rodrigues, Nuno M. Garcia and Pascal
Lorenz, “Object-oriented modelling and simulation of
Optical Burst Switching Networks”, IEEE
Communication Society, GLOBECOM, pp 288-292,
2004, Portugal.