Risk-Aware Routing for Optical Transport Networks

Abstract

A Service Level Agreement (SLA) typically specifies the availability a Service Provider (SP) promises to a customer. In an Optical Transport Network, finding a lightpath for a connection is commonly based on whether the availability of a lightpath availability complies with the connection's SLA-requested availability. Because of the stochastic nature of network failures, the actual availability of a lightpath over a specific time period is subject to uncertainty, and the SLA is usually at risk. We consider the network uncertainty, and study routing to minimize the probability of SLA violation. First, we use a single-link model to study SLA Violation Risk (i.e., the probability of SLA violation) under different settings. We show that SLA Violation Risk may vary by paths and is affected by other factors (e.g., failure rate, connection holding time, etc.), and hence cannot be simply described by path availability. We then formulate the problem of risk-aware routing in mesh networks, in which routing decisions are dictated by SLA Violation Risk. In particular, we focus on devising a scheme capable of computing lightpath(s) that are likely to successfully accommodate a connection's SLA-requested availability. A novel technique is applied to convert links with heterogeneous failure profiles to reference links which capture the main risk features in a relative manner. Based on the "reference link" concept, we present a polynomial Risk-Aware Routing scheme using only limited failure information. In addition, we extend our Risk-Aware Routing scheme to incorporate shared path protection (SPP) when protection is needed. We evaluate the performance and demonstrate the effectiveness of our schemes in terms of SLA violation ratio and, more generally, contrast them with the generic availability-aware approaches.I.

Optimization/simulation-based risk mitigation in resilient green communication networks

“…We base our analysis on this risk measure. Other compensation policies and risk measures to be used in the context of optimized planning of riskaware communication networks are described in Xia et al (2010), Mastroeni andNaldi (2011), Chołda (2014), Chołda et al (2013Chołda et al ( , 2014aChołda et al ( , b, 2015, Chołda and Jaglarz (2015).…”

Energy-efficiency versus resilience: risk awareness view on dimensioning of optical networks with a sleep mode

“…Risk measures are the means for predicting the behavior of network connections before and after deploying the selected risk response. Various known risk measures can be chosen [21,66]. The simplest to interpret is the mean penalty per interval, known as risk exposure (RE): it is the average amount of penalties that reduce the profit.…”

“…Since in the PL network, there are 66 connections (121 for the Ge network), the number of all possible combinations, where each connection may have a different recovery option (skipping re-routing), is 5 66 . They cannot all be analyzed by simulations to obtain the exact risk and energy values.…”

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

“…The fully unshared network consists of two restorable links with two different indices from 1 to R. For example, a 4 × (1 : 1) fully unshared protection scheme contains two restorable links with indices (1, 2), (1,3), (1,4), (2,3), (2,4) and (3,4). Restorable links with indices (1, 2) raise the system availability by…”

“…The SLA is a contract between the optical network operator and a customer guaranteeing certain communication service. A SLA violation may cause a payment of a refund to the harmed customer according to the contract [2][3][4]. The higher the priority of the optical connection required, the higher the availability should be [5,6].…”