Fibre channel arbitrated loop bufferless switch circuitry to increase bandwidth without significant increase in cost

摘要

A switch, switched architecture and process for transferring data through an FCAL switch is disclosed. The switch uses multiple switch control circuits each coupled to one FCAL network and all connected to a crossbar switch. The switch control circuits are coupled together by a protocol bus for coordination purposes. Local conversations can occur on each FCAL loop and crossing conversations through the switch can occur concurrently. The OPN primitive is used to establish the connection before any data is transferred thereby eliminating the need for buffer memory in the switch control circuits. The destination address of each OPN is used to address a lookup table in each switch control circuit to determine if the destination node is local. If not, the destination is looked up and a connection request made on the protocol bus. If the remote port is not busy, it sends a reply which causes both ports to establish a data path through the backplane crossbar switch.

主权项

1. An apparatus comprising:
a plurality of port means for coupling to a plurality of Fibre Channel Arbitrated Loop networks (FCAL nets), each port means configured to couple to a FCAL net and each FCAL net having one or more node loop (NL) nodes thereon; a switching means coupled to said plurality of port means for coupling selectable pairs of said port means together by separate channels; management logic providing a priority level for access to busy destination nodes and wherein the priority level is escalated based on the number of consecutive denials of a connection request; and wherein each of said plurality of port means comprises means for:
receiving an Open Point to Point primitive (OPN) from a source node on the FCAL net coupled to the port means,accessing a routing table, wherein the routing table includes a plurality of Arbitrated Loop Physical Addresses (ALPAs) of the plurality of FCAL nets, using at least an Arbitrated Loop Physical Address (ALPA) of the received OPN primitive to determine which of the plurality of port means a destination node identified in the OPN is coupled to and enable switching of data from the source node to the destination node, andcommunicating with the port means coupled to the destination node to select one of said channels through said switching means and to establish said channel for communication of primitives and data frames between said source node and said destination node.