Optical Networking Best Practices Handbook

1.6. DISTRIBUTED OPTICAL FRAME SYNCHRONIZED RING (DOFSR)

The doFSR is based on a patented frame synchronized ring (FSR) concept. The doFSR is scalable from switching networks to wide area networks (WAN) [6].

The doFSR is a serialized FSR where nodes are connected with high-speed optical links. The basic configuration is two counterrotating rings, but the capacity can be scaled up by using multiple WDM channels or even parallel fiber–links. The capacity can be scaled from 8 Gb/s to 1.6 Tb/s. Multiple doFSR rings can also be chained together to form arbitrary network topologies. Furthermore, the doFSR adapts itself automatically into a large variety of internode distances. In addition, the doFSR is very flexible and scalable from short to long ranges. Furthermore, the members of multicast connections can be added and removed dynamically, so handovers needed by mobile packet traffic are also supported [6].

A doFSR network (see Fig. 1.6) can be composed of multiple doFSRs that contain multiple switching nodes [6]. A switching node contains one or more line units as well as interfaces to other optical networks. Each line unit contains two FSR nodes to connect it to both clockwise and counterclockwise rotating rings. One line unit switching nodes can be connected into the doFSR network by an optical drop/add multiplexer. Larger central office (CO) type of switching nodes (see Fig. 1.7) can have line units for each wavelength pair and they can contain their own optical multiplexers ...