Double-fault shared path protection scheme with constrained connection downtime

Abstract

Conventional end-to-end protection switching schemese.g., Dedicated Path Protection (DPP) and Shared Path Protection (SPP)offer established connections a 100% protection against any single failure in the network. However, in the presence of double failures, the performance of these schemes is not fully pre-determined as it depends upon the failure pattern, network topology, and location of both source and destination of the affected connections.In the paper a methodology is presented that provides a rigorous approach to provisioning connections in the presence of any (multi) link failure pattern. The novelty of the proposed methodology is the introduction of the connection's required Maximum Downtime Ratio (or MDR) into the network protection design process. The connection's reliability degreeexpressed by means of the MDRis now formulated in probabilistic terms, and must be met independently of the topology and location of source and destination. With the proposed methodology, the connection's required MDR is considered as an input parameter. The output is the protection scheme of interest that meets such degree of reliability (MDR) with the minimal use of network resources.To best understand how the proposed methodology works, a study is conducted in which a modified SPP scheme is proposed.To cover a significantly wide range of MDR values the SPP scheme is modified to cope with double link failures. The modified SPP is compared against the DPP in terms of amount of required network resources (cost) versus the connection's required MDR. Results show that with the proposed methodology, it is possible to design and select the most cost-effective protection scheme over a large variety of desired connection's MDR values.

Availability analysis under multiple link failures in WDM networks with shared-link connections

“…Many analytical models have been proposed for evaluating the connection availability in WDM networks under single link failure assumption [3,[7][8][9]. Several analytical models have addressed the dual link failure problem [9][10][11][12][13], but few have been reported for modeling the availability under multiple link failure scenario [14,15]. However, these models only presented a basic analysis of the connection availability.…”

Reducing vulnerability of shared-path protection subject to double-link failures in WDM mesh networks

“…Simultaneous double-link failures can be further divided into two broad categories: Shared risk link group (SRLG)-failure caused double-link failures [14] and arbitrary simultaneous double-link failures [10,11,15]. SRLG-disjoint working path and backup path can offer SRLG failure protection [14], but cannot provide 100% protection against arbitrary double-link failures.…”

A matrix-based analytical approach to connection unavailability estimation in shared backup path protection

“…Previous estimates for the connection unavailability in SBPP rely on conservative upper bounds [2], [3], or approximations [4], [5], which in some cases are insufficient, e.g., if network links have different repair times.…”