| With the fast development of optic-electronics technology, it is necessary that all-optical network, which be composed of optical wavelength division multiplexing transmission systems and optical node equipments, has a great promise for the future communication network. Signal stream is always transmitted and switched by the means of light, and do not need O/E and E/O conversion. Therefore, all-optical network effectively overcomes the electronic bottleneck introduced by complicated digital cross connection equipments, accomplishes fast bit rate, great capacity and good service quality communication, and possesses the transparency for bit rate, data format and modulation means of signal. However, optical internetworking directly based optical wavelength has its intrinsic defects. Firstly, the number of wavelengths that can be multiplexed in the same fiber and regarded as identifiers of wavelength paths established in wavelength-routed network is small, particularly in large-scale one. Secondly, optical nodes usually do not possess the ability of wavelength interchange for the restriction of cost and technology, optical network brings out so-called wavelength continuity constraint because connection must be established on the path that be carried by the same wavelength between source and destination nodes. For the purpose of effectively utilizing resource of network, it is good method that RWA algorithm be performed in optical network.The development of optical network requires the support of key technologies of physical layer of optical network for more and cheaper bandwidth. More bandwidth optical network has, easier the realization optical connection is, on the contrary, less bandwidth, more difficult. So, it is necessary to study key technologies of physical layer of optical network. At present, large-scale optical network is not easily realized, so the study of RWA and its engineering problems on small-scale and middle-scale optical network has important academic and realistic significance. In this paper both the key technologies of physical layer of optical network and RWA of optical network were discussed in detail as follow:1. to simply introduce the current status, trend and significance of research on all-optical network and RWA;2. to analyze some key technologies of optical network relative with RWA in detail, such as transmission, switching and internetworking; to emphasize on the research of function, fabric and performance of optical cross-connection; to carry out numerical simulations for crosstalk introduced by optical cross connect and to present measurements for suppressing it such as doubly filtering, fixing optimum decision threshold and appropriately choosing the number of multiplexed wavelengths;3. to research the fundamental principle and some problems relative with RWA , including the type of optical network, the type of traffic, the type of service, the survivability of optical network; to classify and compare RWA algorithms and particularly research some dynamic RWA algorithms;4. to present reserved light-path and classify network resource such as used, unused and reserved status, to emulate establishment of all-optical connection in optical network through modified RWA algorithm and show effectively reducing setup time of all-optical connection utilizing reserved light-path; to research RWA algorithms of multi-fiber network, to present new link weight functions dependent on node degree, unused fiber(s) per wavelength-layer and routing policies, to perform emulation of RWA based wavelength layer graph applying new link weight functions and show them make algorithms better performance and network lower blocking rate;5. to study the application of RWA for dynamically provisioning bandwidth andrealizing protect & restore in optical network, and the application of optimization of setup time of all-optical connection and blocking rate in multi-fiber network.In a word, we mastered the fundamental principle, the means of algorithms to be optimi...
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