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Chapter 12: Self-Healing On Transparent ... > Conclusion And Future Work - Pg. 287

Self-Healing on Transparent Optical Packet Switching Mesh Networks Figure 7. Packet loss A punishment, in a lower degree, is also applied when a packet is delayed. Figure 7 shows the performance of the net- work before and after the learning process. The lines not only represent the number of packets lost in the routing process but also the number of packets that were traveling in the fiber and will not reach the next node, i.e. not reaching also the final destination. In this plot there are three interesting phenom- ena to be analyzed: 1. The number of lost packets increases as the number of failing wavelengths augments but without blocking all the possible fibers. The number of lost packets is lower when all the wavelengths in a fiber fail. When attacks do not affect all the wave- lengths, even without dimensioning process, the learning process can always improve the performance of the network. 2. 3. case, while the number of failing wavelengths increases the need for delaying or deflecting also increases, in addition as explained above delaying is also punished in the learning process, therefore nodes learned a policy that prefers deflecting over delaying. In the second case, since the dimensioning when blocking all the wavelengths yielded more fibers, the availability of fibers to deflect packets is higher, therefore the loss of packets decreases. Nevertheless, at this point there is an open ques- tion about the reasons of a similar performance before and after learning. For the first and third cases it is clear that the learning process always improved the performance of the network. A second open question concerns whether we can improve this performance or not. CONCLUSION AND FUTURE WORK We have presented an approach for self-healing on TOPS mesh networks; such an approach is composed of two phases. While the first one deals The answer for the first two phenomena relies on the number of available resources. In the first 287