Ahmed Frikha

Extending node protection concept of p-cycles for an efficient resource utilization in multicast traffic

In this paper, we consider link-and-node failure recovery in dynamic multicast traffic in WDM networks. We extend the node protection concept of the p-cycle approach to achieve more efficient resource utilization. Then, we propose a novel algorithm that integrates our concept for the node protection, named node-and-link protecting p-cycle based algorithm (NPC). We also propose a second algorithm, named node-and-link protecting candidate p-cycle based algorithm (NPCC). This algorithm deploys our concept for node protection and relies on a candidate p-cycle set to speed up the computational time. We compare our proposed algorithms to the ESHN algorithm, which is reported to be the most efficient algorithm for protecting dynamic multicast sessions. Extensive simulations show that the NPC algorithm achieves the lowest blocking probability, but has the highest computational time among the NPCC and ESHN algorithms. The NPCC algorithm outperforms the ESHN algorithm in terms of resource utilization efficiency and computational time.

Performance evaluation of pre-computation algorithms for inter-domain QoS routing

Inter-domain QoS routing is a very challenging problem area. This problem combines the complexity of QoS routing, with the limitations of inter-domain routing, such as domain heterogeneity and information confidentiality. The pre-computation offers a very promising solution for addressing this problem. Although the pre-computation scheme has been investigated in several previous studies for a single routing domain, applying pre-computation on an inter-domain level is not straightforward and necessitates deeper investigation. In this work, we study different algorithms for QoS routing based on pre-computation. First, we investigate an exact algorithm. This algorithm provides an optimal solution for the QoS routing problem. However, its application in large scale networks is not always practical. Second, heuristic solutions are also investigated in this work. Particularly, a detailed study of the ID-MEFPA and the ID-PPPA heuristics is provided. Analytical studies and extensive simulations confirm that the exact algorithm achieves the best success rate, but has a very high computational complexity. The ID-MEFPA heuristic has a lower complexity and provides a success rate always close to the exact algorithm. When inter-domain connectivity is high, the ID-PPPA heuristic is the most appropriate with the lowest computation complexity and a success rate very close to the exact algorithm.

Reliable multicast sessions provisioning in sparse light-splitting DWDM networks using p-cycles

In this paper, we study the node and link protection using p-cycles for dynamic multicast sessions in all-optical DWDM networks. First, we propose a new concept for protecting nodes of light-trees under the sparse light-splitting and wavelength continuity constraints. Then, we integrate our concept in a novel algorithm, named node and link protecting candidate p-cycles based algorithm with sparse light-splitting constraints (NPCC-SSC). Our algorithm enables both node and link failure recovery in dynamic multicast traffic. Extensive simulations show that the NPCC-SSC algorithm achieves the best resource utilization, and outperforms the existing approaches in terms of blocking probability and computational time.

Pre-computation based heuristic for inter-domain QoS routing

In the present paper, we propose a novel fast heuristic for inter-domain QoS routing, named ID-PPPA. ID-PPPA is based on a pre-computation scheme. The pre-computation scheme attempts to solve the QoS routing problem while keeping a low response time by computing in advance a set of QoS paths. Our solution preserves domain confidentiality and solves the scaling problem related to inter-domain routing by distributing computations over the domains. Theoretical analysis proves that the ID-PPPA algorithm has a low computational complexity, which is very necessary for a pre-computation algorithm to deal with dynamic changes of the network link state information. Moreover, extensive simulations confirm the efficiency of our algorithm in terms of success rate and quality of the computed path.

Hybrid inter-domain QoS routing with crankback mechanisms

In this paper we tackle the challenging problem of Quality of Service (QoS) routing in multiple domains. We propose a novel inter-domain QoS routing algorithm named HID-MCP. HID-MCP benefits from two major concepts that ensure high performance in terms of success rate and computational complexity. First, HID-MCP is a hybrid algorithm that combines the advantages of pre-computation and on-demand computation to obtain end-to-end QoS paths. Second, HIDMCP integrates crankback mechanisms for improving the path computation results in a single domain or in multiple domains. Extensive simulations confirm the efficiency of our algorithm on randomly generated topologies.

Candidate-cycle-based heuristic algorithm for node-and-link protection of dynamic multicast traffic in optical DWDM networks

Maintaining survivability of DWDM networks is crucial to multicast traffic. A link-or-node failure has a severe impact on optical multicast sessions as it can prune several communications simultaneously. In this paper, we present a novel candidate-cycle-based heuristic algorithm for node-and-link protection (CCHN) in dynamic multicast traffic. CCHN is based on p-cycle protection concept. The p-cycle concept ensures a fast restoration time and an efficient use of network capacity. Extensive simulations show that the blocking probability of our algorithm is lowest. Furthermore, the computational time of our algorithm is very low compared with the existing approaches, especially when traffic load is high.

Applying p-cycle protection for a reliable IPTV service in IP-over-DWDM networks

Today, television over Internet protocol (IPTV) has become very popular and service providers must deal with the rapid growth in the number of IPTV customers. Service providers must ensure the reliability of IPTV to satisfy customers’ needs, as a network failure could disrupt an IPTV transmission.Survivable multicast routing is important for providing a reliable IPTV service. Generally, most carriers route multicast traffic using the protocol-independent multicast source-specific mode (PIM-SSM) based on the routing information provided by the interior gateway protocol (IGP). Restoration using the IGP reconfiguration is slow and typically takes from 10 to 60 seconds. To ensure a fast restoration, we consider node and link failure recovery in the Dense Wavelength Division Multiplexing (DWDM) optical layer. The backup path is provided in this layer. Thus, the multicast tree does not change at the IP layer (the logical links do not change) and the restoration time is faster (typically of the order of 50 to 80 ms).In this paper, we apply p-cycles in IP-over-DWDM networks to provide a robust IPTV service. In addition, we propose a novel concept for node protection using p-cycles to achieve more efficient resource utilization. We also propose a new algorithm, the node and link protecting candidate p-cycle based algorithm (NPCC). This algorithm integrates our new concept for node protection. Extensive simulations show that it outperforms the existing approaches in terms of blocking probability, resource utilization efficiency and computation time rapidity.