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. A process for establishing one or more concurrent data transfers between Fibre Channel nodes comprising the steps:
receiving Fibre Channel frames that are destined for a node coupled to a Fibre Channel port on a switching circuit, the Fibre Channel frames being received from a second switching circuit on a multiplexed bus; receiving a request in the switching circuit coupled to the Fibre Channel port upon which a source node is resident and using an address to determine from a routing table if a destination node is resident upon the Fibre Channel port, wherein said request, from the source node, requests a start of a data transfer with the destination node, said request being in a form of a Fibre Channel message including the address which identifies the destination node with which data is to be exchanged; if said destination node is not resident on said Fibre Channel port, using a control channel on the multiplexed bus having data transfer channels and control channels to circulate said request and address to other switching circuits that include other Fibre Channel ports; and generating, in the switching circuit coupled to the Fibre Channel port upon which said destination node is resident, a grant message identifying the Fibre Channel port upon which said destination node is present by inclusion of a identification code of the switching circuit coupled to the Fibre Channel port on which said destination node is present in said grant message.