Switch fabric access scheduler

Abstract

A switch fabric access scheduler is disclosed. An indication is received that a link included in a plurality of links to the switch fabric is next in order to be serviced by a queue scheduling process common to the plurality of links. The queue scheduling process common to the plurality of links is used to determine, in a manner at least partly independent of each other link in the plurality, a queue to be serviced by the link.

1 . A method of providing access to a switch fabric, comprising: 
 receiving an indication that a link included in a plurality of links to the switch fabric is next in order to be serviced by a queue scheduling process common to the plurality of links; and    using the queue scheduling process common to the plurality of links to determine, in a manner at least partly independent of each other link in the plurality, a queue to be serviced by the link.    
   
   
       2 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the plurality of queues are used to buffer data to be transferred to the switch fabric via the link.  
   
   
       3 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the switch fabric is a striped switch fabric.  
   
   
       4 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the switch fabric is a non-striped switch fabric.  
   
   
       5 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the scheduling processes uses for each link a link-specific set of scheduling state variables.  
   
   
       6 . A method of providing access to a switch fabric as recited in  claim 5 , wherein the link-specific scheduling state variables include an index (I) variable and a round (R) variable.  
   
   
       7 . A method of providing access to a switch fabric as recited in  claim 5 , further comprising updating the scheduling state variables.  
   
   
       8 . A method of providing access to a switch fabric as recited in  claim 5 , further comprising determining the current value of each of one or more link-specific scheduling state variables specific to the link including by obtaining from a designated storage location the current value of each of the one or more link-specific scheduling state variables specific to the link.  
   
   
       9 . A method of providing access to a switch fabric as recited in  claim 8 , wherein said designated storage location is one of a plurality of storage locations, and further comprising storing in each of said plurality of storage locations one or more scheduling state variables specific to a different one of said plurality of links.  
   
   
       10 . A method of providing access to a switch fabric as recited in  claim 9 , wherein said plurality of storage locations are arranged in a ring and the method further comprises rotating the ring by shifting the data in each storage, so that the data stored in the designated location corresponds to a next link to be serviced.  
   
   
       11 . A method of providing access to a switch fabric as recited in  claim 10  further comprising updating the one or more scheduling state variables specific to the selected link.  
   
   
       12 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the queue scheduling process employs a weighted round robin (WRR) scheme.  
   
   
       13 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the queue scheduling process employs a weighted fair queueing (WFQ) scheme.  
   
   
       14 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the queue scheduling process employs a deficit round robin (DRR) scheme.  
   
   
       15 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the queue scheduling process employs a strict priority (SP) scheme.  
   
   
       16 . A method of providing access to a switch fabric as recited in  claim 1 , wherein the queue scheduling process employs a round robin (RR) scheme.  
   
   
       17 . A system for providing access to a switch fabric comprising: 
 a buffer configured to store a plurality of queues; and    a queue scheduler associated with the buffer and common to a plurality of links, configured to: 
 receive an indication that a link included in the plurality of links to the switch fabric is next in order to be serviced by the queue scheduler; and  
 select, in a manner at least partly independent of each other link in the plurality, one of the plurality of queues as the next queue to be serviced by the link.  
   
   
   
       18 . A computer readable medium comprising a computer program product for providing access to a switch fabric, the computer program product comprising computer instructions which when executed perform the following: 
 receiving an indication that a link included in a plurality of links to the switch fabric is next in order to be serviced by a queue scheduling process common to the plurality of links; and    using the queue scheduling process common to the plurality of links to determine, in a manner at least partly independent of each other link in the plurality, a queue to be serviced by the link.