Scalable switching fabric

#This invention relates to switching fabrics used to switch data in computer networks and other data moving applications.

#Crossbars are one type of switching fabric used to switch data between pluralities of devices. They can be thought of as a switch that has a plurality of vertical paths interconnected by switching elements to a plurality of horizontal paths in a manner that the switch elements can interconnect any one of the vertical paths to any one of the horizontal paths. Generally such crossbars are implemented with custom application specific integrated circuits (ASIC's).

#According to an aspect of the present invention, a switch fabric includes a network switch having a plurality of inputs and outputs and a distributed switching arrangement to provide a non-blocking switching fabric capability over a series of byte sliced buses.

#FIG. 1 is a block diagram of a network system including a rotary switch.

#FIG. 2 is block diagram showing an implementation of the rotary switch.

#FIG. 3 is a block diagram of the rotary switch.

#Referring to FIG. 1, a networked system 10 includes a rotary switch 12 transfering data from input ports to output ports in a non-blocking manner. For instance, the switch can be used for sending packet data at plurality of network processors 14 to network devices 16 coupled to separate 32 bit FIFO busses. The rotary switch 12 includes a data path that is sliced or partitioned on an 8 bit (i.e. byte) basis to allow system 10 to be expanded from e.g., a 2×2 FIFO bus system to an 8×8 FIFO bus system and so forth as described below. The rotary switch 12 includes a plurality of 8-bit wide Virtual Input Queues (“VIQ”) 18 that are distributed into input segments with each of 8 byte wide input segments coupled to 16 of the VIQ's 18. The rotary switch device 12 also includes a plurality of Output Segments 20.

#The rotary switch 12 also includes a switching fabric network 24 which in combination with the Virtual Input Queues and output segment logic 20 can move byte wide data from any of the plurality of Input Virtual Queues 18 to an output FBUS byte without restricting the access of any other input segment to any of Input Virtual Queues 18. Data switching is controlled by a arbiter 22.

#The internal fabric 24 of the RSC 12 provides full input to output connectivity that is, a full of any and all of the inputs to any and all of the outputs. In a exemplary rotary switch 12, there are 128 8-bit wide Virtual Input Queues (“VIQ”), distributed over 8 segments e.g., 16 VIQ's per segment and 8 output segments, thus providing a device 12 having 128 input ports to any of the 128 output ports. The fabric is an independently queued structure that does not require symmetric switching. The switching is a distributed function between a loose arrangement among processors 14 and the RSC fabric 24. The RSC arbiter 22 provides a fair round robin service for received packets. The processors 14 can provide packets either through a simple round robin or weighted fair queuing to the RSC 12. The output port switching is based on a PULL arbitration scheme.