An All-Optical WDM Packet-Switched Network Architecture with Support for Group Communication

The paper investigates the use of group communication to improve the efficiency of load balancing in interconnected LANs. Conventional load balancing techniques usually assume point-to-point connections among the computers and typically work on a single LAN only. This may waste network bandwidth and lengthen the load balancing time in LANs that support group communication such as the Ethernet. To tackle this problem a two level algorithm is proposed. At the LAN level, all computers in a LAN maintain loading information in the entire LAN using a globally ordered group channel. The workload in the different LANs is balanced by moving load from the overloaded LANs to the underloaded ones. It is proved that the proposed algorithm converges to the state of global balance geometrically. Experimental results show that the algorithm reduces load balancing time and network utilization significantly, compared to the single level algorithm without group communication.

This community service activity is motivated by the local potential of Darungan Hamlet in utilizing herbal plants as health drinks, but is still limited in the aspects of processing, packaging, and marketing. This condition results in low product added value and limited economic opportunities for the community, especially members of the Catleya 3 Dasawisma Group. Motivating the mothers of the Catleya 3 Dasawisma members to become productive individuals will be an opportunity to improve and enhance the quality of family life economically. One effort that can be done is by providing scientific provisions that they can apply by creating something that has economic value. One of these is by making a health drink by utilizing natural resources that can grow well and are abundantly available in Jember. The goal of this activity is to increase the knowledge, skills, and economic independence of the community through innovative herbal dip products and the use of digital technology in marketing. The methods used include socialization, pre-tests and post-tests, training in making herbal dip with three flavors, application of production and packaging technology, and training in creating e-commerce-based marketing accounts. The target of the activity was members of the Catleya 3 Dasawisma Group located in the RT 04/RW 08 area of ​​Darungan Hamlet with a total of 20 participants. The increase in participants' understanding of the use of herbal medicines increased as seen from the average post-test score (80.53±15.80) which was higher than the pre-test score (59.47±13.93). Participants were able to produce herbal dip hygienically and of good quality, package products with attractive labels, and have knowledge related to product marketing through Shopee and Tokopedia. In addition, participants demonstrated independence in managing small businesses based on local potential with the support of production facilities and group communication. This activity succeeded in increasing community knowledge regarding the benefits of traditional medicinal ingredients and how to utilize them, entrepreneurial skills, and expanding participants' knowledge to create e-commerce accounts. Thus, the purpose of community service was achieved, namely the realization of increasing community skills in producing herbal dip sustainably.

Current group communication services have mostly been implemented on a homogeneous, distributed computing environment. This limits their applicability because most modern distributed computing environment are heterogeneous in nature. This paper describes the design, implementation, and performance evaluation of a CORBA group communication service. Using CORBA to implement a group communication service enables that group communication service to operate in a heterogeneous, distributed computing environment. To evaluate the effect of CORBA on the performance of a group communication service, this paper provides a detailed comparison of the performance measured from three implementations of an atomic broadcast protocol and a group membership protocol. Two of these implementations use CORBA, while the third uses UDP sockets for interprocess communication. The main conclusion is that heterogeneity can be achieved in group communication services by implementing them using CORBA, but there is a substantial performance cost. This performance cost can be reduced to a certain extent by carefully choosing a design and tuning various protocol parameters such as buffer sizes and timer values.

OMG has published an unreliable multicast specification for distributed applications developed in CORBA (UMIOP). This mechanism can be implemented based on IP Multicast, a best-effort protocol, which provides no guarantees about the message delivery. However, many fault-tolerant or groupware applications demand more restrictive agreement and ordering guarantees (for instance, reliable multicast with FIFO, causal or total ordering) from the available support for group communication. OMG has not yet provided any specification for supporting those requirements. This paper presents an important contribution towards this direction. We proposed the ReMIOP, an extension to the UMIOP/OMG protocol, for the conception of a reliable multicast mechanism in CORBA middleware. Performance measures comparing ReMIOP, UMIOP and UDP sockets for IP multicast communication are presented in order to evidence the costs for adding reliable and unreliable multicast in middleware level.

Mobile radio group communications enable a closed group of users to communicate among themselves using push-to-talk (PTT), half duplex transmissions, such that one's transmission is received by all. New protocol designs are presented which support group communications over mobile satellite systems. A new demand assignment multiple access (DAMA) protocol is necessitated by the inappropriateness of call-based channel assignments. Channels are assigned to individual user-groups engaged in active conversations. As members of a user-group contend for access to the assigned channel, access control by the usual manual methods is ineffective due to the very long round trip delay. A novel signaling protocol which automates access control is proposed. Carrier sensing, signal capture, and collision detection are employed to minimize access contentions. The throughput and holding time of the assigned channel are analyzed. Numerical results show that the access control protocol improves the capacity of the assigned channel by up to 65%. >

Group communications are commonly used in parallel and distributed environment. However, existing migration mechanisms do not support group communications. This weakness prevents migrationbased proactive fault tolerance, among others, to be applied to MPI applications. In this study, we propose distributed migration protocols with group membership management to support process migration with group changing. We design and implement a process migration enabling MPI library, named MPIMitten, to verify the protocols and enhance current MPI platforms for reliability and usability. MPI-Mitten is based on MPI standard and can be applied to any MPI-2 implementations. Experimental results show the proposed distributed process migration protocols are solid and the MPI-Mitten system is effective and is uniquely supporting migration-based fault tolerance.

A photonic 2x2 node architecture for synchronous all-optical packet switching networks, able to process ultra-fast packet signals is presented. All node functions (label recognition and processing, contention detection and resolution, switch control, actual switching, and regeneration) are optically performed. Combinations of the proposed 2times2 element can be used in order to obtain more complex NtimesN photonic nodes. Implementations of all subsystems needed to realize the describe 2times2 photonic node are reported, and different solutions for several blocks are compared in order to optimize the node performances.

Telecommunication networks are evolving due to rapid growth of internet traffic and the necessity to satisfy the new requirements of emerging packet services. Upgrading of network devices so as they can allow scalable and full line rate traffic aggregation and eliminate any internal performance bottlenecks is crucial. In packet switching devices, since data plane functionalities need to be executed for each incoming packet and power per given bandwidth is strongly related to the amount of processing on this data, packet processing at ultra-high rate is becoming the major challenge. The main trend to address such power consumption and scalability issues is to bypass packet switches by switching traffic at lower layers. This results in the packet optical transport network approach, where packet switching provides flexible end-to-end connectivity based on tunnel encapsulation while wavelength switching, exploiting optical bypass, allows reducing electrical switch size at transit nodes. There are also opportunities consisting in simplifying packet switch functionalities or designing completely different packet switch architectures. In this paper a new Ethernet aggregation and switching solution with potentialities to simplify and scale Ethernet switch forwarding functionality is proposed. This solution, based on a burst-basis transmission compliant with the Ethernet Standard, is able to maintain flexibility and any to any connectivity deriving from the connectionless nature of Ethernet. At the same time, it provides Ethernet technology with efficient aggregation capabilities allowing to reduce processing of transit traffic. This is allowed thanks to an Ethernet burst structure conceived as a variable number of consecutive frames of the same connection preceded by a proprietary burst control frame carrying information necessary for burst data frames classification. As a result, burst control frames experience the conventional Ethernet switch packet processing while data frames are mapped on the corresponding queue/output port according to the result of control frames classification. The proposed solution also provides the possibility to recognize data frames of the same burst through a proprietary inter-frame gap inserted among them; that allows to dynamically adapt burst size to the available bandwidth at transit nodes in order to limit frame delay and jitter and to support intermediate grooming. These features make it a very competitive approach in the context of packet optical transport being able to support dynamic multi-granular switching. The proposed solution has been validated by estimating its efficiency in terms of energy consumption with respect to a commercial packet switch. The impact of burst transmission on packet delay and jitter across ring and mesh networks has been also evaluated through different sets of simulations.

Many applications of wireless sensor networks require collaboration among sensor nodes to achieve a common task. Moreover, this is often dynamic in nature. For instance, in multi-object tracking, sensor nodes that are tracking various moving objects must share information in order to improve the tracking quality. Thus, it is important to have a protocol that maintains group connectivity in such a setting. In this paper, we study the problem of maintaining communication paths among a group of moving agents that have interacted with one another. As its solution, we propose a data structure called the distributed collaboration graph (DCG), which is a communication graph obtained from the agent trajectories. The DCG can be constructed in a purely distributed fashion with very little cost and can be used for group discovery and for multicasting/broadcasting among agents. We also propose a distributed protocol which maintains a communication tree among the agents within the DCG while the agents are moving. This allows us to maintain group connectivity and provides the infrastructure for routing among the moving agents.

The authors examine a growable architecture for broadband packet (asynchronous transfer mode) switching, consisting of a memoryless, self-routing interconnect fabric and modest-size packet switch modules, proposed by K.U. Eng et al. (1989). They focus on the cell loss probability, because the architecture attains the best possible delay-throughput performance if the packet switch modules use output queueing. They compute an upper bound on the cell loss probability for arbitrary patterns of independent cell arrivals, possibly including isochronous circuit connections, and show that both sources of cell loss can be made negligibly small. For example, to guarantee a cell loss probability of less than 10/sup -9/, this growable architecture requires packet switch modules of dimension 47*16, 45*16, 42*16, and 39*16 for 100%, 90%, 80%, and 70% traffic loads, respectively. The analytic techniques used to bound the cell loss probabilities are applicable to other output queueing architectures. >

In this paper we present a GMPLS-based control plane framework for the integrated hybrid optical networks (IHON). IHON supports both packet switching (PS) and circuit switching (CS) forwarding paradigms in the same node. It is integrated because the low-priority PS traffic is inserted in the same channels as the high-priority CS traffic to increase the overall wavelengths utilization. We make use of new standardized functionalities within GMPLS for multi-region networks (MRN) that extend the description of the network resources with both packet and circuit switching capabilities. The framework applies GMPLS to the IHON network in order to control the label switched paths (LSP) for the circuit and packet forwarding paradigms. The control plane is integrated so that a single GMPLS instance is used to control both PS and CS virtual network topologies. The logical inter-operation is given through a detailed illustration. Our approach is to adapt the IHON control-plane logic to be fully described by the standardized GMPLS framework. The framework is compatible with the standardized GMPLS protocol suite, is independent of specific labeling schemes for physical differentiation of CS and PS forwarding, and requires no extra control messages.

Object replication is a technique to enhance fault tolerance and high availability. Group communication is a useful mechanism guaranteeing the consistency among replicated objects. We propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. For this, we extend the Open Communications Interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. The proposed scheme is composed of group membership, group IOR, and group multicast. Experimental results show that group object invocation using the proposed scheme performs substantially better than group object invocations using IIOP as the number of members in a group increases.

This paper presents PLATO, an analytical technique to model the performance in all-optical packet-switched networks with various topologies and node architectures. Using this technique, we propose a two-part algorithm, incorporating mathematical analysis and a numeric method, to model the network's traffic flow and the local packet-loss probability inside each node. The PLATO technique has demonstrated excellent accuracy with two different representative network topologies and node architectures. It has considerably reduced the time required to evaluate the performance of all-optical packet-switched networks.

This paper presents a comparative study of contention-resolution schemes based on wavelength, time, and space domains in an unslotted optical packet-switched network with a large irregular mesh topology consisted of 15 nodes. For the first time, to the best of our knowledge, we investigated the effect of selective deflection and limited wavelength conversion. Features and performances of different combinational schemes are listed and compared. While simulation results show the effectiveness of wavelength conversion for resolving contentions over optical buffering and space deflection, physical explanations of the different effectiveness in resolving contentions of these schemes are also discussed.

We propose two almost-all optical packet switch architectures, called the packing switch and the scheduling switch, which when combined with appropriate wait-for-reservation or tell-and-go connection and flow control protocols provide lossless communication for traffic that satisfies certain smoothness properties. Both switch architectures preserve the order of packets that use a given input-output pair, and are consistent with virtual circuit switching. We find a lower bound on the number of elementary (2-state) switches required by any switch architecture to meet the objectives we have set. The number of 2-state switches used in the scheduling switch is of the optimal order jointly with respect to the number of inputs and with respect to the burstiness of the traffic streams (as measured by an appropriate parameter). The packing switch requires very little processing of the packet header, and uses a number of 2-state switches that is of the optimal order in terms of the burstiness parameter. We also examine the suitability of the proposed switches for the design of circuit switched networks. We find that the scheduling switch combines low hardware cost with little processing requirements at the nodes, and is an attractive architecture for both packet switched and circuit switched high-speed networks.