Fabrication & Demonstration of a WDM, ATM, Multicast Switch.

摘要

The moment we proposed the work (1993), we have to take care the need of both an OTDM and a WDM networks. The technologies we developed here are useful for either approach. Basically, for each incoming packet/cell from all the optical channels, we need to align them in time before they entering the NxN space switch fabrics. A tunable optical delay line controlled by calculated electrical signals is needed. We may also need to change the information in the packet header before it leaves the switch and goes to the next node. The information could be the VCI in a system using the virtual-channel routing scheme or the packet delay in a burst switching system where the header is ahead of the packet payload. The delay between the header and the payload is changing at each node due to the add-on packet processing delay and the contention resolution delay. Before achieving both of the above functions (tunable delays and header information overwriting) an important function has to be performed and that is the cell or packet delineation function. The work is basically to identify the packet or cell boundaries from a stream of 1-0 optical signals. In a SONET system, the framing function is provided. When we run IP or cells directly on top of an optical channel, the cell or packet boundaries have to be identified.