An effective hybrid buffering optical packet switch for contention resolution

Packet contention is a critical factor in optical packet switching network. It is not a trivial task to resolve due to lack of optical RAM technology. In order to resolve contention, optical buffering approach is used which are implemented using fiber delay lines (FDLs). Optical buffering approach is fundamental to many optical switch implementations to resolve contention. This paper focuses on contention resolution using fiber delay lines (FDLs). Most of the existing optical buffering schemes are output-based which require huge number of FDLs as well as larger switch size that incur extra implementation cost. Shared buffering approach is considered in this paper to reduce implementation cost. This paper investigates the performance of hybrid buffering optical packet switch to resolve contention, which uses a set of feed-forward shared fiber delay lines and a set of feedback shared fiber delay lines. Feed-forward FDLs are deployed as primary buffer and feedback FDLs are implemented as supplementary buffer. The hybrid buffered switch leads to more efficient use of the buffer space compared to output buffering. The performance of the switch is evaluated by means of simulation experiments. Simulation result shows that proposed hybrid buffering switch achieves lower packet loss rate at the price of a reasonable amount of FDLs. Moreover, the performance is compared with feed-forward shared buffering architecture to justify the significance of the switch.