Virtual path shaping

Abstract

Apparatus and method for shaping ATM cell traffic emitted onto a virtual path connection in an ATM network are described. Component virtual channel connections are arbitrated at an aggregation point utilizing an arbitration technique. The technique provides both virtual path shaping and controllability of underlying virtual channel connections with an improved fairness performance amongst all the aggregating virtual channel connections.

1 . A device for scheduling virtual channel connections carrying cell traffic of different categories of service onto a virtual path connection comprising: 
 aggregating means for aggregating virtual channel connections of similar categories of service into a single cell stream.    
     
     
         2 . A device as defined in  claim 1  wherein virtual channel connections carrying different categories of service are queued in separate queues.  
     
     
         3 . A device as defined in  claim 2  wherein said aggregating means includes means to form groups of said separate queues  
     
     
         4 . A device as defined in  claim 3  wherein said aggregating means includes arbitration means.  
     
     
         5 . A device as defined in  claim 4  wherein said aggregation means includes means to form per-VCC like-service-category queues and said arbitration means arbitrates priority as between said like-category-queues.  
     
     
         6 . A device as defined in  claim 5  wherein said arbitration means includes means to arbitrate priority as between said separate queues within said groups of queues.  
     
     
         7 . A device as defined in  claim 1  including multi-level arbitration means to arbitrate between virtual channel connections in an hierarchical manner.  
     
     
         8 . A device as defined in  claim 6  including shaper means to determine egress time of cells in said single cell stream.  
     
     
         9 . A device as defined in  claim 8  wherein said egress time is shaped in accordance with traffic descriptors specified for said virtual path connection.  
     
     
         10 . A device for shaping virtual channel connections carrying cell traffic of different categories of service onto a virtual path connection comprising: queuing means for queuing cells of like-service-categories; arbitration means for arbitrating between said queues; and shaper means for shaping said cells into a single cell stream on said virtual path connection.  
     
     
         11 . In an ATM data communications network utilizing virtual channel connections wherein said virtual channel connections are aggregated at an aggregation point onto virtual path connections, an apparatus for shaping ATM cell traffic comprised of various categories of service onto said virtual path connection, said apparatus comprising: 
 queuing means for queuing cells from each of said virtual channel connections;    arbitration means to arbitrate between said virtual channel connection traffic; and    a virtual path connection shaper to determine egress emission time of cells from said arbitration means onto said virtual path connection.    
     
     
         12 . An apparatus as defined in  claim 11  wherein said virtual channel connections carry different categories of service cell traffic.  
     
     
         13 . An apparatus as defined in  claim 12  wherein said queuing means queues said virtual channel connections according to said category of service.  
     
     
         14 . An apparatus as defined in  claim 13  wherein said arbitration means arbitrates priority as between said virtual channel connections.  
     
     
         15 . An apparatus as defined in  claim 14  further including second arbitration means to arbitrate priority as between categories of service.  
     
     
         16 . An apparatus as defined in  claim 15  wherein said categories of service comprise real time and non-real time service classes  
     
     
         17 . An apparatus as defined in  claim 16  wherein said real time class of service include constant bit rate (CBR) and real time variable bit rate(rtVBR) traffic.  
     
     
         18 . An apparatus as defined in  claim 16  wherein said non-real time class of service includes non-real time variable bit rate (nrtVBR) available bit rate (ABR) and unspecified bit rate (UBR).  
     
     
         19 . An apparatus as defined in  claim 11  wherein said shaper determines egress time of cells in accordance with traffic descriptors.  
     
     
         20 . An apparatus as defined in  claim 19  wherein said traffic descriptors include peak cell rate (PCR), sustained cell rate (SCR) and maximum burst size (MBS).  
     
     
         21 . An apparatus as defined in  claim 15  wherein said second arbitration means utilizes an exhaustive round-robin arbitration scheme.  
     
     
         22 . An apparatus as defined in  claim 15  wherein said second arbitration means utilizes a weighted round-robin arbitration scheme.  
     
     
         23 . An apparatus as defined in  claim 15  wherein said second arbitration means utilizes a weighted fair queuing arbitration scheme.  
     
     
         24 . In an ATM data communications network having virtual channel connections channel aggregated at an aggregation point onto virtual path connections, a method for fairly shaping ATM cell traffic comprised of various categories of service and quality of service parameters onto said virtual path connection, said method comprising the steps of: 
 queuing said virtual channel connection cell traffic in separate queuing buffers;    arbitrating between said separate queuing buffers utilizing an arbitration means; and    shaping said arbitrated cell traffic with a virtual path connection shaper in order to fairly emit said cell traffic onto said virtual path connection.    
     
     
         25 . A device for arbitrating and shaping virtual channel connections (VCC) onto a virtual path connection (VPC) wherein said virtual channel connections carry ATM cell traffic of different categories of service, said device comprising: queuing means for forming per-VCC queues containing similar category of service cells; first arbitration means within each per-VCC queue for arbitrating priority between similar category of service cells; a second arbitration means for arbitrating priority between said per-VCC queues; and shaper means for determining egress time of said cells from said second arbitration means onto said virtual path connection.  
     
     
         26 . A device as defined in  claim 25  wherein a third arbitration means arbitrates between some of said per-VCC queues with the results of said third arbitration means being arbitrated by said second arbitration means together with the other per-VCC queues.  
     
     
         27 . A device as defined in  claim 26  wherein said first arbitration means is a round robin scheme.  
     
     
         28 . A device as defined in  claim 26  wherein said second arbitration means is an exhaustive round robin scheme.  
     
     
         29 . A device as defined in  claim 26  wherein said third arbitration means is a weighted round robin scheme.