Switching in core optical networks is currently being performed using high-speed electronic or all-optical circuit switches. Switching with high-speed electronics requires optical-to-electronic (O/E) conversion of the data stream, making the switch a potential bottleneck of the network: any effort (including parallelization) for electronics to approach the optical speeds seems to be already reaching its practical limits. Furthermore, the store-and-forward approach of packet-switching does not seem suitable for all-optical implementation due to the lack of practical optical Random-Access-Memories to buffer and resolve contentions. Circuit switching on the other hand, involves a pre-transmission delay for call setup and requires the aggregation of microflows into circuits, sacrificing the granularity and the control over individual flows, and is inefficient for bursty traffic. Optical burst switching (OBS) has been proposed by Qiao, C., ? to combine the advantages of both packet and circuit switching and is considered a promising technology for the next generation optical internet.
Key Terms in this Chapter
Grid: GRID is an emerging computing model that provides the ability to execute complex processing tasks in a number of distributed, inter-networked computers.
FDL: Fiber delay line is a fixed length of fibre that is used to induce a given delay in the passing through optical signal.
GMPLS: Generalized multi-protocol label switching protocol allows traffic paths to be set up through a switched network automatically. This involves the configuration of core switches for the transparent forwarding data from a given start to given end point.
OXC: Optical cross-connect is network device (switch fabric) used by network operators to switch high-speed optical signals. It is capable of switching multiple high-speed signals that are not multiplexed together.
Quality of Service (QoS): Refers to the capability of a telecommunication network to meet a requested quality or traffic contract. In many cases quality of service is refered to the probability of a packet succeeding in propagating through a certain link or path in the network, within its delay bounds.
Optical Burst Switching (OBS): A new switching concept which lies between optical circuit switching and optical packet switching. In optical burst switching, the switching payload is the aggregation of numerous packets, usually call burst of packets.