Method and System for Managing Time Division Multiplexing (TDM) Timeslots in a Network Switch

Abstract

A system and method for managing the allocation of Time Division Multiplexing (TDM) timeslots in a network switch. The network switch may use a TDM cycle comprising multiple timeslots to manage shared resources and to schedule data ingress and egress through the ports of the current configuration, wherein each port is assigned one or more timeslots. The network switch may be reprogrammed to support one of multiple timeslot assignment schemes for one of multiple port configurations. The network switch may support configurations with varying numbers of ports, e.g. 8- and 16-port configurations. A network switch may also support configurations where two or more ports are combined to form one port, for example, a 2 Gbs Fibre Channel port. To meet the requirements of the various configurations, the timeslot assignment scheme may be reprogrammed to meet the scheduling requirements of each of the possible port configurations.

1 . A method for managing assignment of Time Division Multiplexing (TDM) timeslots of a TDM cycle in a network switch that includes a plurality of ports configured to receive input data and convey output data for the network switch, the method comprising: 
 programming the network switch to support a first TDM timeslot assignment scheme for a first configuration of the ports, wherein the programmed network switch is configured to schedule the receiving of the input data and the conveying of the output data through the first configuration of the ports using the first TDM timeslot assignment scheme; and    reprogramming the network switch to support a second TDM timeslot assignment scheme for a second configuration of the ports, wherein the reprogrammed network switch is configured to schedule the receiving of the input data and the conveying of the output data through the second configuration of the ports using the second TDM timeslot assignment scheme.    
     
     
         2 . The method as recited in  claim 1 , wherein the network switch further includes one or more programmable registers, and further comprising: 
 storing the first programmed TDM timeslot assignment scheme in the one or more programmable registers, wherein the network switch is configured to access the first programmed TDM timeslot assignment scheme from the one or more programmable registers when scheduling data through the first configuration of the ports.    
     
     
         3 . The method as recited in  claim 2 , further comprising: 
 storing the second programmed TDM timeslot assignment scheme in the one or more programmable registers, wherein the network switch is configured to access the second programmed TDM timeslot assignment scheme from the one or more programmable registers when scheduling data through the second configuration of the ports.    
     
     
         4 . The method as recited in  claim 1 , wherein the first configuration of the ports comprises N ports and the second configuration of the ports comprises 2N ports, where N is a positive integer.  
     
     
         5 . The method as recited in  claim 1 , wherein the TDM cycle comprises a first group of consecutive read timeslots and a second group of consecutive write timeslots.  
     
     
         6 . The method as recited in  claim 5 , wherein the TDM cycle further comprises a first turnaround timeslot after the last read timeslot and a second turnaround timeslot after the last write timeslot, wherein the first turnaround timeslot is used for transitioning from read to write operations and the second turnaround timeslot is used for transitioning from write to read operations.  
     
     
         7 . The method as recited in  claim 5 , wherein the first group comprises 2N read timeslots and the second group comprises 2N write timeslots.  
     
     
         8 . The method as recited in  claim 5 , wherein each of the N ports in the first configuration of the ports is assigned two read timeslots and two write timeslots in the TDM cycle.  
     
     
         9 . The method as recited in  claim 8 , wherein the two read timeslots for each of the N ports are adjacent to each other and the two write timeslots for each of the N ports are adjacent to each other.  
     
     
         10 . A network switch comprising: 
 a plurality of ports configured to receive input data and convey output data for the network switch; and    scheduler logic coupled to the ports, the scheduler logic being configured to schedule receiving of the input data and conveying of the output data through the ports using a Time Division Multiplexing (TDM) cycle comprising a plurality of timeslots, 
 wherein the network switch is programmable to implement any of a plurality of TDM timeslot assignment schemes for the TDM cycle, each of the plurality of TDM timeslot assignment schemes supporting a different configuration of the ports in the network switch, and the network switch is further reprogrammable from a first TDM timeslot assignment scheme supporting a first configuration of the ports in the network switch to a second TDM timeslot assignment scheme supporting a second configuration of the ports in the network switch.  
   
     
     
         11 . The network switch as recited in  claim 10 , further comprising: 
 one or more programmable registers, wherein the programmable registers are configured to store a TDM timeslot assignment scheme programmed into the network switch and the scheduler logic is configured to access the TDM timeslot assignment scheme stored in the one or more programmable registers for scheduling data through the plurality of ports.    
     
     
         12 . The network switch as recited in  claim 11 , further comprising: 
 a TDM random access memory configured to store received data for the network switch, wherein the scheduler logic is coupled between the TDM random access memory and the ports.    
     
     
         13 . The network switch as recited in  claim 11 , wherein the first configuration supports N ports of the plurality of ports and the second configuration supports 2N ports of the plurality of ports, where N is a positive integer.  
     
     
         14 . The network switch as recited in  claim 13 , wherein the TDM cycle comprises a first group of consecutive read timeslots and a second group of consecutive write timeslots.  
     
     
         15 . The network switch as recited in  claim 14 , wherein the TDM cycle further comprises a first turnaround timeslot after the last read timeslot and a second turnaround timeslot after the last write timeslot, wherein the first turnaround timeslot is used for transitioning from read to write operations and the second turnaround timeslot is used for transitioning from write to read operations.  
     
     
         16 . The network switch as recited in  claim 14 , wherein the first group comprises 2N read timeslots and the second group comprises 2n write timeslots.  
     
     
         17 . The network switch as recited in  claim 14 , wherein each of the N ports in the first configuration is assigned two read timeslots and two write timeslots in the TDM cycle.  
     
     
         18 . The network switch as recited in  claim 17 , wherein the two read timeslots for each of the N ports in the first configuration are adjacent to each other, and wherein the two write timeslots for each of the N ports in the first configuration are adjacent to each other.  
     
     
         19 . The network switch as recited in  claim 18 , wherein each of the 2N ports in the second configuration is assigned one read timeslots and one write timeslot in the TDM cycle.  
     
     
         20 . A method comprising: 
 providing one or more programmable registers in a network switch that includes a plurality of ports configured to receive input data and convey output data for the network switch, the one or more programmable registers being configured to store at least one of a plurality of Time Division Multiplexing (TDM) timeslot assignment schemes supported by the network switch.    configuring the network switch to schedule the receiving of the input data and the conveying of the output data through a first configuration of the ports using a first TDM timeslot assignment scheme read from the one or more programmable registers; and    configuring the network switch to schedule the receiving of the input data and the conveying of the output data through a second configuration of the ports using a second TDM timeslot assignment scheme read from the one or more programmable registers.