In traditional optical networks, configured as static physical pipes, the carrier-grade network resilience is provided by means of protection and restoration capabilities. However, there is a need to develop a new generation of dynamic reconfigurable all optical networks with built in network resilience capabilities. In the next generation, high-speed photonic packet switching networks, ultrafast packet header processing, and packet switching are the vital building blocks. In this chapter, a review of different routing schemes for high-speed photonic packet switching networks and the concept of reducing the size of the look-up routing table are presented. A novel PPM signal format has been introduced in order to reduce the size of the routing table in order reduce packet switching and processing time compared to the conventional routing tables. A failure self detection and a routing table reconfiguration in the optical domain are introduced, and a number of factors such as system performance, reliability, and complexity are also discussed.
TopIntroduction
In recent years we have seen a remarkable progress in research to increase the long-haul optical fibre back-bone transmission distance as well as exploiting its virtually unlimited transmission bandwidth (70 THz (“Annual Report,” 2005)) to deliver multiplicity of services to the end users at a global scale. Nowadays, systems capable of delivering Terabits/s over optical fibre communication networks spanning tens of thousands of kilometres are practically feasible (Suzuki, Fujiwara, & Iwatsuki, 2006; Zhu, Funabashi, Pan, Paraschis, & Yoo, 2006). These outstanding achievements are due to a number of technical breakthroughs in the optical domain such as low attenuation (< 0.25 dB/km) optical fibres at S- and L-bands, erbium doped fibre amplifiers and Raman amplification at C, L and S bands, the distributed amplification, effective long-haul dispersion management schemes (Doerr, et al., 2006), tunable lasers, gain equalisation, optical multiplexing/demultiplexing techniques (Bergano, 2005; Ohara, et al., 2004), inline all-optical repeaters and all optical buffering (Dorren, et al., 2003; Hunter, Chia, & Andnovic, 1998; Takahashi, et al., 2004), advanced error detection/correction schemes (Choi, et al., 2005), packet compression/decompression techniques (Takenouchi, Takahata, Nakahara, Takahashi, & Suzuki, 2004), all-optical gates and switches (Guo & Connelly, 2006; Zhang, Wu, Feng, Xu, & Lin, 2007) and high-quality system resilience features (K.K. Lee, Lim, & Ong, 2005).
Nevertheless, the ever-growing demand for the data based services and applications, e.g. e-services and e-applications or broadband access networks are the driving forces for upgrading the existing network and deployment of optical networks at a larger scale at all network levels. With the future data traffic being Internet Protocol (IP) based services (multimedia, e-learning), there is the need for improved interface between the existing transmission protocols (e.g. ISO/OSI-protocol stack) and the physical layer (dominated by the optical transmission). Seamless integration of optical networks with conventional network applications and services has resulted in further developments and a broader deployment of optical networks in all areas of modern telecommunication networks. These networks can be classified and distinguished between Access Networks (including fibre-to-the-home (FTTH) and fibre-to-the-business (FTTB)), the Metropolitan Area Network (MAN), Wide Area Network (WAN), and high-speed indoor multiple access networks. Therefore, the increase in demand for reliable routing of optical data entirely in the optical domain imposes many challenges such as the ability of the network to efficiently and economically process and switch a huge amount of optical data at every router while maintaining high-quality network management and resilience under faults and malicious attacks (Fu-Tai, et al., 2004).