Quality of service using virtual channel translation

Abstract

Virtual channels are used to improve quality of service through a large port count switch. Data frames are sent from one small switch to another small switch within the large port count switch on virtual channels. The use of virtual channels helps prevent congestion caused by a first external source device sending data to a first external destination device from affecting a second external source device sending data to a second external destination device.

1 . A method for sending Fibre Channel data frames through a Fibre Channel switch, the Fibre Channel switch comprising a plurality of small switches, the Fibre Channel data frames having a source and a destination, the destination being used for routing the Fibre Channel data frame, comprising: 
 receiving the Fibre Channel data frame from the source at a first small switch;    choosing a first virtual channel from a set of possible virtual channels, each virtual channel of the set of possible virtual channels being available for use with general data flow;    providing information in addition to the Fibre Channel data frame to identify the first virtual channel; and    sending the Fibre Channel data frame and the additional information identifying the first virtual channel from the first small switch to a second small switch,    wherein the first virtual channel is chosen based on the identity of the source of the Fibre Channel data frame.    
     
     
         2 . A Fibre Channel switch for switching Fibre Channel data frames, the switch comprising: 
 a first small Fibre Channel switch; and    a second small Fibre Channel switch coupled to the first small Fibre Channel switch, wherein each small Fibre Channel switch includes: 
 a plurality of ports including a plurality of external ports for coupling to external devices and a plurality of internal ports for connection to a small Fibre Channel switch;  
 a plurality of buffers, each buffer associated with a respective virtual channel; and  
 logic operable to determine an identification of a destination of a Fibre Channel data frame for routing purposes based on the destination address of the Fibre Channel data frame and to determine an identification of a virtual channel available for general data flow to apply to received Fibre Channel data frames, wherein the identification of the virtual channel can be done by one of at least two bases, and  
 wherein the first small Fibre Channel switch uses a first basis to identify the virtual channel and the second small Fibre Channel switch uses a second, different basis to identify the virtual channel.