Abstract
Survivability of internet services is a significant and crucial challenge in designing optical networks. A robust infrastructure and transmission protocols are needed to maintain communication, despite the existence of one or more failed components on the system. Here, we present a generalized approach to tolerate any set of failure scenarios to the extent network users can still communicate with the remaining components, where a scenario is an arbitrary set of links in a non-operational state. We propose a joint solution to assess the survivability problem. The issues to be solve simultaneously are as follows: the set of primary routes, a collection of alternate routes associated with each failure scenario, and the capacity required on the network to allow communication between all users, in spite of any considered failure scenario, while satisfying for each user a specific predefined quality of service threshold, defined in the Service Level Agreement (SLA). Numerical results show that the proposed approach not only enjoys the advantages of low complexity and ease of implementation, but it is also able to achieve significant resource savings compared to existing methods. The savings are higher than 30% on single link failures and more than 100% on two simultaneous link failures cases or in more complex failure scenarios.
Highlights
A remarkable issue to be solved when designing WDM (Wavelength Division Multiplexing) optical networks is to ensure that the network will still be able to provide transmission services after the failure of one or more of its links
It is known that the Routing and Wavelength Dimensioning (RWD) problem belongs to the NP-complete class [46]
The dimensioning method does not make any distinction between primary and alternative routes, with the constraint that it only evaluates scenarios that may happen during the network operation
Summary
A remarkable issue to be solved when designing WDM (Wavelength Division Multiplexing) optical networks is to ensure that the network will still be able to provide transmission services after the failure of one or more of its links. The method evaluates the number of wavelengths for each link of the network, ensuring that the blocking probability of any user request is lower than a given corresponding predefined threshold βc, despite the possible occurrence of those simultaneous link failures This dimensioning problem is specially tricky when the network has wavelength continuity constraint (the case analyzed here). One of the most frequent ways used to address single and double fault tolerance, called ‘‘1+1’’, can be found in [5], [21], [22] In this technique, a secondary route is associated with each primary one (with the restriction that they do not share any link), and the information is transmitted simultaneously through both of them, avoiding restoration delays in case of a failure. The method proposed here is applicable to any set of failure scenarios, with the condition that the network remains connected after any of the failure scenarios considered, which implies that the method can provide alternative routes for all affected users
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