Network-Wide Local Unambiguous Failure Localization (NWL-UFL) via Monitoring Trails

Abstract

Monitoring trail (m-trail) has been proposed as an effective approach for link failure localization in all-optical WDM (Wavelength Division Multiplexing) mesh networks. Previous studies in failure localization rely on alarm dissemination via control plane signaling such that the network controller can collect the flooded alarms to form an alarm code for failure identification. Such cross-layer signaling effort obviously leads to additional control complexity. The paper investigates a novel m-trail failure localization scenario, called network-wide local unambiguous failure localization (NWL-UFL), where each node can perform UFL based on locally available on-off state of traversing m-trails, such that alarm dissemination in the control plane can be completely avoided. The paper firstly defines and formulates the m-trail allocation problem under NWL-UFL, and conducts a series of bound analysis on the cover length required for localizing any single link failure. This is the first study on monitoring trail allocation problem which aims to gain understanding on the consumed cover length via analytical approaches due to the special feature of the NWL-UFL scenario. A novel heuristic algorithm based on random spanning tree assignment (RSTA) and greedy link swapping (GLS) is developed for solving the formulated problem. Extensive simulation on thousands of randomly generated network topologies is conducted to verify the proposed scheme by comparing it with a naive counterpart and with the derived lower bounds. We also demonstrate the impact of topology diversity on the performance of the proposed scheme as well as its scalability regarding network sizes.

BER Degradation Detection and Failure Identification in Elastic Optical Networks

“…Since x tends to be 0 when no meaningful period is observed, we use a Gaussian distribution centered in 0 and with a standard deviation inversely proportional to the number of periods over the mean (line 18). Feature probability is eventually computed and P H updated (lines [19][20].…”

“…Regarding failure localization, several works in the literature have proposed methods for localization of hard link failures that affect a number of established connections, focused on reducing restoration times (see, e.g., [19]- [21]). All the proposed methods basically consist on computing and establishing a number of auxiliary connections (m-trails or mcycles).…”

Neighborhood Failure Localization in All-Optical Networks via Monitoring Trails

“…By properly allocating a set of m-trails in the network, an all-optical monitoring system is formed, so that every node can unambiguously identify the failed link by only inspecting the m-trails traversing through the node. This is also referred to as the network-wide local unambiguous failure localization (NWL-UFL) scenario [2]. In [3] NWL-UFL was taken as a building block for constructing the first all-optical failure restoration framework, which enables a general shared protection scheme to be performed in an all-optical and signaling-free fashion.…”

On achieving all-optical failure restoration via monitoring trails

“…By properly allocating a set of m-trails in the network, an all-optical monitoring system is formed, so that every node can unambiguously identify the failed link by only inspecting the m-trails traversing through the node. This is also referred to as the network-wide local unambiguous failure localization (NWL-UFL) scenario [2]. In [3] the first all-optical failure restoration framework, which enables a general shared protection scheme to be performed in an all-optical and signaling-free fashion.…”

“…Although theoretically sound, [2], [3] assumed that each node is able to unambiguously identify all possible failures. Thus a node will monitor a remote link even if the node does not need to respond to the link failure, resulting in unnecessary monitoring resource consumption, high computation complexity, and very lengthy m-trails.…”