A failure in optical backbone network can cause tremendous consequences as a substantial number of connections often each carrying a large amount of data can be interrupted. Therefore, high reliability performance is essential for the network operators. Many existing works that aim at improving network reliability performance implicitly assume that the lifetime of devices is constant and independent of the traffic load. However, the reliability performance of a device is related to its occupancy. For example, the failure rate of erbium doped fiber amplifier (EDFA) can be expressed as a function of the number of amplified wavelengths. On the other hand, the choice of routing and wavelength assignment (RWA) algorithm impacts the link load and, as a consequence, can influence the number of EDFA failures in the network.

In this paper we examine how RWA can impact the failure reparation related network operational costs. Several types of RWA approaches are considered, namely load-balancing, energy-awareness, and reliability-awareness. Among all the considered RWA algorithms, the reliability-aware RWA (RA-RWA) approach leverages on EDFA reliability profile to reduce the number of EDFA failures in the network and the related operational costs.

The simulation results show that the RWA algorithm impacts in a significant way the operational costs caused by EDFA failures. The cost associated with reparation of an EDFA decreases by 7.8% (in case of RA-RWA) and increases by up to 40% (in case of a load-balancing approach) compared to the classical Shortest Path (SP) approach. Moreover, the cost caused by connection rerouting due to link unavailability triggered by EDFA failure exhibits a 20% decrease (RA-RWA) and up to 94% increase (energy-aware algorithm). We also analyze some key network performance metrics that may be affected by RWA, including blocking probability, link occupancy distribution, and path length.

光纤骨干网的故障可能会导致巨大的后果，因为经常会承载大量数据的大量连接可能会中断。因此，高可靠性性能对于网络运营商至关重要。许多旨在提高网络可靠性性能的现有工作隐含地假定设备的寿命是恒定的，并且与流量负载无关。但是，设备的可靠性性能与其占用率有关。例如，do掺杂光纤放大器（EDFA）的故障率可以表示为放大波长数的函数。另一方面，路由和波长分配（RWA）算法的选择会影响链路负载，结果可能会影响网络中EDFA故障的数量。

在本文中，我们研究了RWA如何影响与故障赔偿相关的网络运营成本。考虑了几种类型的RWA方法，即负载平衡，能源意识和可靠性意识。在所有考虑的RWA算法中，可靠性感知RWA（RA-RWA）方法利用EDFA可靠性概况来减少网络中EDFA故障的次数以及相关的运营成本。

仿真结果表明，RWA算法对EDFA故障导致的运营成本产生了重大影响。与传统的最短路径（SP）方法相比，与EDFA的修复相关的成本降低了7.8％（在RA-RWA的情况下），最高增加了40％（在负载平衡的情况下）。此外，由EDFA故障触发的链路不可用性导致的连接重新路由导致的成本降低了20％（RA-RWA），最高提高了94％（能量感知算法）。我们还分析了一些可能受到RWA影响的关键网络性能指标，包括阻塞概率，链路占用分布和路径长度。