The Agile All-photonic Backbone Network (AAPN) architecture has been proposed by the telecommunication industry as a potential candidate for the ultra high speed Next Generation Optical Network (NGON) architecture. AAPN network structure is composed of adaptive optical core switches and edge routers in an overlaid star physical topology. The AAPN employs fast packet switching architecture for the network traffic, and the packet scheduling is the main part of the AAPN. The objective is to forward the packets to their destination with the lowest drop rate and delay, the bandwidth allocation can be either located at the core node or the edge switch. Two types of scheduling are considered in the AAPN architecture, namely the centralized and the distributed schemes. In the centralized scheme all decisions are made at the core node while in the distributed scheme, they are made at the edge nodes. In this paper, we want to compare both scheduling schemes. We would also like to propose a promising integrated TDM architecture that combines the good attributes of both centralized and distributed scheduling schemes. We shall characterize such architecture by various measures such as delay and loss probabilities.
All-Optical networks with the DWDM technology provide huge bandwidth and are the sole approach for transporting huge network traffic. However, this bandwidth is too coarse to be used by a single user and this is why the Optical Time Division Multiplexing (O-TDM) has been deployed in the optical networks to provide finer granularity and improve bandwidth usage. In contention-based slotted-optical networks, because there is no collaboration among the ingress switches, the data slots on the same wavelength and time-slot destined to the same destination may collide. In this paper, we detail contention avoidance schemes in two software and hardware categories and show that edge switches can have an important role in reducing loss rate in optical networks by transmitting traffic to each destination with equal probability (symmetric traffic transmission) and balancing traffic load on the wavelength channels. We also show that edge switches can have an important role in the loss rate reduction issue in optical networks by reducing traffic load and using more wavelengths/fibers to carry the same traffic.