A router for use in a network includes a scalable architecture and
performs methods for implementing quality of service on a logical unit
behind a network port; and for implementing storage virtualization. The
architecture includes a managing processor, a supervising processor; and
a plurality of routing processors coupled to a fabric. The managing
processor has an in-band link to a routing processor. A routing processor
receives a frame from the network, determines by parsing the frame, the
protocol and logical unit number, and routes the frame to a queue
according to a traffic class associated with the logical unit number in
routing information prepared for the processors. An arbitration scheme
empties the queue in accordance with a deficit round robin technique. If
a routing processor detects the frame's destination is a virtual entity,
and so is part of a virtual transaction, the router conducts a nonvirtual
transaction in concert with the virtual transaction. The nonvirtual
transaction accomplishes the intent of the virtual transaction but
operates on an actual network port, for example, a storage device.