Optical layer monitoring schemes for fast link failure localization in all-optical networks

Optical layer monitoring and fault localization serves as a critical functional module in the control and management of optical networks. An efficient monitoring scheme aims at minimizing not only the hardware cost required for 100{%} link failure localization, but also the number of redundant alarms and monitors such that the network fault management can be simplified as well. In recent years, several optical layer monitoring schemes were reported for fast and efficient link failure localization, including simple, non-simple monitoring cycle (m-cycle) and monitoring trail (m-trail). Optimal ILP (Integer Linear Program) models and heuristics were also proposed with smart design philosophy on flexibly trading off different objectives. This article summarizes those innovative ideas and methodologies with in-depth analysis on their pros and cons. We also provide insights on future research topics in this area, as well as possible ways for extending the new failure localization approaches to other network applications. © 2005 IEEE.published_or_final_versio

Super monitor design for fast link failure localization in all-optical networks

Monitoring cycle (m-cycle) based design is cost efficient for fast link failure detection and localization in all-optical networks. An m-cycle is an optical loop-back pre-cross-connection of a supervisory wavelength with a dedicated monitor. Generally, a simple monitor is placed at an arbitrary node of an m-cycle for supervision. In this paper, we propose a novel monitor structure, called super monitor. A super monitor is used to supervise multiple intersecting cycles and placed at the intersection node. For a given set of m-cycles, we use super monitors to replace some (or all) simple monitors that originally locate in the set. Two major advantages of the super monitor are: 1) it has lower hardware cost; 2) the collocation of monitoring devices reduces the management cost simultaneously. Besides, the super monitor does not incur additional bandwidth cost. We formulate an integer linear program (ILP) to solve the problem of monitor placement. Numerical results show that our ILP can efficiently place the monitors with a significantly minimized monitoring cost. © 2011 IEEE.published_or_final_versionThe 2011 IEEE International Conference on Communications (ICC 2011), Kyoto, Japan, 5-9 June 2011. In Proceedings of the IEEE ICC, 2011, p. 1-

Heuristic algorithm for fault detection and path performance monitoring in meshed all-optical networks

Fault detection is critical for all-optical networks (AONs). This paper introduces the concept of monitoring cycles and proposes a mechanism for fault detection and path performance monitoring based on decomposing AONs into monitoring cycles. Two monitoring cycle finding algorithms are developed: heuristic depth first searching (HDFS) and shortest path Eulerian matching (SPEM). The two algorithms are compared in terms of wavelength overhead in nodes and links. It is shown that the proposed fault detection mechanism based on monitoring cycles is effective and cost efficient. Heuristic depth first searching (HDFS): 1) Given graph G(V, E) , let the cycle cover C = = = null ; number all nodes in V; and label all nodes in V and all links in E as “uncovered”; 2) Select an uncovered link e in E, if multiple such links are available; select the uncovered link whose endpoints are also uncovered. Start DFS from e and go to that Uncovered endpoints of e if possible; if no uncovered link with uncovered endpoint is available, apply the largest/smallest rule described below; 3) At each step of the DFS, select an uncovered link if possible. If multiple links are available, alternatively use the largest/smallest node number first rule in the iteration, e.g. if the last time we selected the node with the largest number among multiple nodes with the same priority, then this time we select the node with the smallest number; 4) Once a link returns to the previously visited part, a cycle c can be formed and add the cycle to the cover C; label all the links and nodes in cycle c as “covered”; 5) Repeat (2)-(4) until all links in E are “covered”. Shortest path Eulerian matching (SPEM): (1) For a non-Eulerian graph G (V, E), find the set V’ of odd-degree nodes; (2) Start from a node x∈∈∈V’ and find the shortest path to every other node, select the smallest one among them, denote as p(x, y). Add path p(x, y) to G (now some links in G are “doubled”) and remove x, y from V’ ; (3) Repeat (2) until V’ = = = null. Now G (V, E) is Eulerian; (4) Find an Eulerian cycle of the augmented G(V, E) and decompose it to a cycle cover as mentioned above. This paper introduced the concept of monitoring cycles and proposed a fault detection and path performance monitoring mechanism based on decomposing AONs into monitoring cycles. The heuristic depth first searching (HDFS) and shortest path Eulerian matching (SPEM) algorithms are developed for finding monitoring cycles in AONs. The two algorithms are compared with respect to the maximum and average number of wavelengths occupied by monitoring in nodes and links. The results for the 4 network examples show that the wavelength overhead is pretty low with this mechanism. Thus the proposed mechanism based on monitoring cycles is a promising fault detection method for AONs. It is also applicable to path transmission performance monitoring. The results also suggest that the SPEM algorithm is better than the HDFS algorithm in terms of the wavelength overhead

Monitoring Cycle Design for Fast Link Failure Localization in All-Optical Networks

A monitoring cycle (m-cycle) is a preconfigured optical loop-back connection of supervisory wavelengths with a dedicated monitor. In an all-optical network (AON), if a link fails, the supervisory optical signals in a set of m-cycles covering this link will be disrupted. The link failure can be localized using the alarm code generated by the corresponding monitors. In this paper, we first formulate an optimal integer linear program (ILP) for m-cycle design. The objective is to minimize the monitoring cost which consists of the monitor cost and the bandwidth cost (i.e., supervisory wavelength-links). To reduce the ILP running time, a heuristic ILP is also formulated. To the best of our survey, this is the first effort in m-cycle design using ILP, and it leads to two contributions: 1) nonsimple m-cycles are considered; and 2) an efficient tradeoff is allowed between the monitor cost and the bandwidth cost. Numerical results show that our ILP-based approach outperforms the existing m-cycle design algorithms with a significant performance gain.published_or_final_versio

Monitoring trail: on fast link failure localization in all-optical WDM mesh networks

We consider an optical layer monitoring mechanism for fast link failure localization in all-optical wavelength-division-multiplexing (WDM) mesh networks. A novel framework of all-optical monitoring, called monitoring trail (m-trail), is introduced. It differs from the existing monitoring cycle (m-cycle) method by removing the cycle constraint. As a result, m-trail provides a general all-optical monitoring structure, which includes simple, nonsimple m-cycles, and open trails as special cases. Based on an in-depth theoretical analysis, we formulate an efficient integer linear program (ILP) for m-trail design to achieve unambiguous localization of each link failure. The objective is to minimize the monitoring cost (i.e., monitor cost plus bandwidth cost) of all m-trails in the solution. Numerical results show that the proposed m-trail scheme significantly outperforms its m-cycle-based counterpart.published_or_final_versio

Ethernet - a survey on its fields of application

During the last decades, Ethernet progressively became the most widely used local area networking (LAN) technology. Apart from LAN installations, Ethernet became also attractive for many other fields of application, ranging from industry to avionics, telecommunication, and multimedia. The expanded application of this technology is mainly due to its significant assets like reduced cost, backward-compatibility, flexibility, and expandability. However, this new trend raises some problems concerning the services of the protocol and the requirements for each application. Therefore, specific adaptations prove essential to integrate this communication technology in each field of application. Our primary objective is to show how Ethernet has been enhanced to comply with the specific requirements of several application fields, particularly in transport, embedded and multimedia contexts. The paper first describes the common Ethernet LAN technology and highlights its main features. It reviews the most important specific Ethernet versions with respect to each application field’s requirements. Finally, we compare these different fields of application and we particularly focus on the fundamental concepts and the quality of service capabilities of each proposal

Survivability aspects of future optical backbone networks

In huidige glasvezelnetwerken kan een enkele vezel een gigantische hoeveelheid data dragen, ruwweg het equivalent van 25 miljoen gelijktijdige telefoongesprekken. Hierdoor zullen netwerkstoringen, zoals breuken van een glasvezelkabel, de communicatie van een groot aantal eindgebruikers verstoren. Netwerkoperatoren kiezen er dan ook voor om hun netwerk zo te bouwen dat zulke grote storingen automatisch opgevangen worden. Dit proefschrift spitst zich toe op twee aspecten rond de overleefbaarheid in toekomstige optische netwerken. De eerste doelstelling die beoogd wordt is het tot stand brengen vanrobuuste dataverbindingen over meerdere netwerken. Door voldoende betrouwbare verbindingen tot stand te brengen over een infrastructuur die niet door een enkele entiteit wordt beheerd kan men bv. weredwijd Internettelevisie van hoge kwaliteit aanbieden. De bestudeerde oplossing heeft niet enkel tot doel om deze zeer betrouwbare verbinding te berekenen, maar ook om dit te bewerkstelligen met een minimum aan gebruikte netwerkcapaciteit. De tweede doelstelling was om een antwoord te formuleren om de vraag hoe het toepassen van optische schakelsystemen gebaseerd op herconfigureerbare optische multiplexers een impact heeft op de overleefbaarheid van een optisch netwerk. Bij lagere volumes hebben optisch geschakelde netwerken weinig voordeel van dergelijke gesofistikeerde methoden. Elektronisch geschakelde netwerken vertonen geen afhankelijkheid van het datavolume en hebben altijd baat bij optimalisatie