The proliferation of QoS-aware group applications coupled with the limited availability of network resources demands efficient mechanisms to support QoS multicasting. During a life-cycle of a multicast session, three ...
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The proliferation of QoS-aware group applications coupled with the limited availability of network resources demands efficient mechanisms to support QoS multicasting. During a life-cycle of a multicast session, three important events can occur: membership dynamics, network dynamics, and traffic dynamics. The first two are concerned with maintaining a good quality (cost) multicast tree taking into account dynamic join/leave of members, and changes in network topology due to link/node failures/additions, respectively. The third aspect is concerned with flow, congestion, and error control. There have been many solutions proposed for dealing with each of these issues. However, the issue of tree migration has not been addressed as part of these solutions. In this paper, we highlight the importance of tree migration as a mechanism for handling membership and network dynamics in core-based I multicasting, prove that it is NP-complete, and propose four heuristic algorithms for it. The proposed algorithms are evaluated under two performance metrics: service disruption and resource wastage. Our simulation studies show that two of the algorithms offer comparable performance to that of the other two, in addition to being highly scalable and easily implementable.
Previous advances in photonic switching have paved the way for realizing all-optical time switched networks. The current technology of wavelength division multiplexing (WDM) offers bandwidth granularity that match pea...
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ISBN:
(纸本)0780370163
Previous advances in photonic switching have paved the way for realizing all-optical time switched networks. The current technology of wavelength division multiplexing (WDM) offers bandwidth granularity that match peak electronic transmission speed by dividing the fiber bandwidth into multiple wavelengths. However, the bandwidth of a single wavelength is too large for certain traffic. Time division multiplexing (TDM) allows multiple traffic streams to share the bandwidth of a wavelength efficiently. While introducing wavelength converters and time slot interchangers improve the network blocking performance, it is often of interest to know the incremental benefits offered by every additional stage of switching. As all-optical networks in future are expected to employ heterogeneous switching architectures, it is necessary to have generalized network model that allows one to study these networks under a unified framework. In this paper, a network model, called the Trunk Switched Network (TSN), is proposed to facilitate modeling and analysis of such networks. An analytical model for evaluating the blocking performance of a class of TSN's has also been developed. Using the analytical model, it is shown that a significant performance improvement is obtained with a time-space switch with no wavelength conversion at each node in a multi-wavelength TDM switched network.
Though the areas of secure multicast group architecture, key distribution and sender authentication are under scrutiny, one topic that has not been explored is how to integrate these with multilevel security. Multilev...
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Though the areas of secure multicast group architecture, key distribution and sender authentication are under scrutiny, one topic that has not been explored is how to integrate these with multilevel security. Multilevel security is the ability to distinguish subjects according to classification levels, which determines to what degree they can access confidential objects. In the case of groups, this means that some members can exchange messages at a higher sensitivity level than others. The Bell-La Padula model outlines the rules of these multilevel accesses (see Bell, D. and La Padula, L., MITRE Report, M74-244, MTR 2547 v2, 1973). In multicast groups that employ multilevel security, some of these rules are not desirable, so a modified set of rules is developed and is termed differential security. Also, this paper proposes three methods to set up a differentially secure multicast group: (1) naive approach, (2) multiple tree differential security (DiffSec) approach, and (3) single DiffSec tree approach. Our simulation studies show that both single and multiple DiffSec tree approaches offer similar performance in terms of bandwidth consumption, which is significantly better than that of the naive approach. We also discuss the suitability of the schemes, taking into account scalability and implementation issues.
In packet-switched networks, queueing of packets at the switches can result when multiple connections share the same physical link. To accommodate a large number of connections, a switch can employ link-scheduling alg...
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ISBN:
(纸本)0818680164
In packet-switched networks, queueing of packets at the switches can result when multiple connections share the same physical link. To accommodate a large number of connections, a switch can employ link-scheduling algorithms to prioritize the transmission of the queued packets. Due to the high-speed links and small packet sizes, a hardware solution is needed for the priority queue in order to make the link schedulers effective. But for good performance, the switch should also support a large number of priority levels (P) and be able to buffer a large number of packets (N). So a hardware priority queue design must be both fast and scalable (with respect to N and P) in order to be implemented effectively. In this paper, we first compare four existing hardware priority queue architectures, and identify scalability limitations on implementing these existing architectures for large N and P. Based on our findings, we propose two new priority queue architectures, and evaluate them using simulation results from Verilog HDL and Epoch implementations.
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