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ABSTRACT: Ethernet protocol is the most wide-spread protocol in the local area network (LAN) environment. It is cost effective, simple, and provides high speeds, exactly what is needed in the provider network. However, deployment in the provider network imposes carrier-grade requirements. Standardization bodies realized this, and they are extending its capabilities: QoS support and traffic management by 802.1Q virtual LANs (VLANs), traffic engineering by 802.1s multiple spanning tree protocol (MSTP), administration and management issues by 802.1 ag connectivity fault management (CFM). However, with carrier-grade extensions Ethernet started to lose an important property: simplicity. Often the topology of the Ethernet aggregation is simple, tree-like, so complex protocols like MSTP are not required even when resilience is supported by adding several links. In most cases the plain rapid spanning tree protocol (RSTP) can provide the necessary restoration and loop protection capability. However, the default settings of the RSTP protocol may not provide optimal network utilization, and it is difficult to predict its behavior after a failure. In this paper we present a tool for RSTP optimization, which engineers the network for best utilization while also ensures that optimal paths will be selected after a link failure. The result of the optimization is a port cost set for all bridge interfaces. The optimization is performed off-line using an integer linear program (ILP). We show that compared to the default settings higher throughput can be achieved, while the required bandwidth is guaranteed in case of any link failure.
Access Networks & Workshops, 2007. AccessNets '07. Second International Conference on; 09/2007
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ABSTRACT: In optical networks that are based on provisioned or switched lambda-paths there is no support for sub-lambda granularity, and therefore, the network is not efficient for carrying demands of bandwidth requirement significantly smaller than the capacity of a lambda-path. Even if we add a layer over the lambda-layer to improve granularity and also add grooming capability the network will not be efficiently utilised unless the added upper layer supports statistical multiplexing. The focus of this paper is on showing that in such a two-layer network neither statistical multiplexing in itself nor the traffic grooming with deterministic multiplexing itself can utilise the resources efficiently but only the joint use of both. We perform a simulation study to compare deterministic multiplexing to three different models for statistical multiplexing for two cases, namely, when all nodes are capable of grooming and when no node is capable of grooming at all. The lowest blocking and highest throughput has been achieved for the case of joint use of grooming and statistical multiplexing, particularly when the bandwidth requirements of demands are significantly smaller than the capacity of lambda-channels
Transparent Optical Networks, 2006 International Conference on; 07/2006
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ABSTRACT: Ethernet is being increasingly employed in metro networks. Ethernet gives routing schemes and protocols for building up trees, for instance STP, RSTP and MSTP. It also implies simple restoration mechanisms. In this paper we propose an optimization framework, where the Ethernet MSTP trees are protected and QoS is guaranteed even after a failure. The optimization is based not only on the topology, but it also takes traffic conditions and QoS constraints into account. The numerical results show that the proposed optimization significantly increases the throughput of the network. The best result can be achieved when preemption is assumed, i.e., when the best effort traffic may remain unprotected, but not the high priority one. This way high throughput can be realized at normal operation, while it still protects prioritized traffic in case of a failure. Furthermore, protection mechanisms act faster than the standard restoration mechanism resulting shorter out-of-service times, and therefore higher availability.
Design of Reliable Communication Networks, 2005. (DRCN 2005). Proceedings.5th International Workshop on; 11/2005
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ABSTRACT: In multi-layer networks, where more than one layer is dynamic, i.e., connections are set up using not only the upper, e.g., IP layer but the underlying wavelength layer as well leads often to suboptimal performance. In this paper we discuss the lightpath fragmentation and de-fragmentation problem, where the lightpath system cannot follow the traffic changes fast enough. We show what it depends on, when is it critical and how much does it deteriorate the performance of the network.
Transparent Optical Networks, 2005, Proceedings of 2005 7th International Conference; 08/2005
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Multimedia Services Access Networks, 2005. MSAN '05. 2005 1st International Conference on; 07/2005
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NETWORKING 2006. Networking Technologies, Services, and Protocols; Performance of Computer and Communication Networks; Mobile and Wireless Communications Systems.
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Proceedings World Telecommunications Congress.
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Infocommunications Journal.
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Proceedings 1st International Conference on Multimedia Services Access Networks (MSAN’2005) pp.
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IFIP Lecture Notes in Computer Science (LNCS). 3976(3976):715-726.
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ABSTRACT: Triple Play requires cost-effective implementation of three services that are different in both traffic and QoS requirements. The methods applied for optimization of Ethernet trees must support not only point-to-point pipes but also point-to-multipoint connections for multicast and statistical multiplexing models for better resource allocation. In this paper we present a QoS architecture for Triple Play service over metro Ethernet networks. Based on the architecture we propose an optimization framework and a novel scalable heuristic algorithm that supports optimal off-line configuration of trees and optimal VLAN assignment to these trees. The optimized configuration considers traffic engineering (TE) objectives and can be performed via centralized management plane. The obtained results show, that the performance of the proposed optimization framework can be further improved if the aggregation pipes are statistically multiplexed. Meanwhile, the proposed algorithm remains scalable, i.e. its complexity does not increase at all
Next Generation Internet Design and Engineering, 2006. NGI '06. 2006 2nd Conference on;
