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

• US 8,750,320 B2
• Filed: 01/21/2003
• Issued: 06/10/2014
• Est. Priority Date: 01/23/1997
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Black, Alistair D., Chan, Kurt
• Primary Examiner(s): Sefcheck, Gregory
• Assistant Examiner(s): Kang, Suk Jin
• Application Number:
  US10/348,721
• Publication Number:
  US 20030169753A1
• Time in Patent Office: 4,158 Days
• Field of Search: 370/403
• US Class Current: 370/403
• CPC Class Codes: H04L 12/40084 Bus arbitration
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• CPC Class Codes: H04L 12/4637 Interconnected ring systems
• CPC Class Codes: H04L 49/103 using a shared central buffer; using a shared memory
• CPC Class Codes: H04L 49/15 Interconnection of switching modules
• CPC Class Codes: H04L 49/254 Centralised controller, i.e. arbitration or scheduling
• CPC Class Codes: H04L 49/30 Peripheral units, e.g. input or output ports
• CPC Class Codes: H04L 49/357 Fibre channel switches
• CPC Class Codes: H04L 49/40 Constructional details, e.g. power supply, mechanical construction or backplane
• CPC Class Codes: H04N 21/4341 Demultiplexing of audio and video streams

Abstract

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.

Claims

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, and

communicating 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.

2. The apparatus of claim 1, wherein the channel through said switching means is using at least one data path and is a virtual channel allowing concurrent data transfers through the switching means.

3. A device comprising:

a plurality of ports configured to couple to a plurality of Fibre Channel Arbitrated Loop networks (FCAL nets), each of the ports configured to couple to a FCAL net and each FCAL net having one or more node loop (NL) nodes thereon;

a switch unit coupled to said plurality of ports and configured to couple selectable pairs of said ports together by separate channels; and

a routing table coupled to at least one of the plurality of ports including Arbitrated Loop Physical Addresses (ALPAs) of a plurality of FCAL Nets and mapping to their associated ports;

each of said plurality of ports comprising;

a receiving unit configured to receive an open point to point primitive (OPN) from a source node on the FCAL net coupled to the port, and

a determination unit configured to access a routing table using at least an Arbitrated Loop Physical Address (ALPA) of the OPN primitive to determine which of the plurality of ports a destination node identified in the OPN is coupled to and enable switching of data from the source node to the destination node,

management logic providing a priority level for access to busy destination nodes and the priority level is escalated based on the number of consecutive denials, and

a communication unit configured to communicate with the port coupled to the destination node to a select one of said channels through said switch unit and to establish said channel for communication of primitives and data frames between said source node and said destination node.

4. The device of claim 3, wherein the channel through the switch unit is using at least one data path and is a virtual channel allowing concurrent data transfers through the switch unit, which includes a crossbar switch.

5. The device of claim 3, further comprising a first-in first-out (FIFO) buffer for managing priority level requests for the at least one port of the plurality of ports.

6. The device of claim 3, each of said plurality of ports further comprising:

a transmitting unit for forwarding the open primitive (OPN) to the destination node, when control of the FCAL net is won following an arbitration for the FCAL net; and

the receiving unit configured to receive an Receive Ready (RRDY) primitive or a Close (CLS) primitive from the destination node in the second port and transmitting the primitive to the source node through the channel,

wherein the device continues to pass data frames and primitives between the source node and the destination node using Fibre Channel primitive messaging to provide flow control to indicate when to hold back and when to transmit data frames, until a CLS primitive is transmitted by either the source or the destination node, and then closing the channel and relinquishing control of the FCAL net coupled to the port.

7. The device of claim 3, further comprising a Joint Test Action Group (JTAG) circuit residing on the device for testing.

8. The device of claim 3, further comprising:

a serializer/deserializer function coupled to at least one of the plurality of ports that demultiplexes received encoded serial data and multiplexes outgoing data; and

an elastic buffer memory coupled to at least one of the plurality of ports to absorb differences between receive and transmit data rates on the at least one of the plurality of ports.

9. The device of claim 3, further comprising a microprocessor coupled to a switch unit to perform functions related to configuring the device.

10. The device of claim 3, further comprising a multiplexed bus for communicating with a second device, wherein a virtual channel is established for each data flow allowing multiple data flows to be sent and received by the device on the multiplexed bus, wherein channels for communication on the multiplexed bus include data channels and at least one channel dedicated to other uses.

11. A method of switching with a plurality of ports that are coupled to a plurality of Fibre Channel Arbitrated Loop networks (FCAL nets), each of the ports configured to couple to a FCAL net and each FCAL net having one or more node loop (NL) nodes thereon, the method comprising:

receiving by at least one port of the plurality of ports an open point to point primitive (OPN) from a source node on the FCAL net coupled to the at least one port;

accessing a routing table that includes a plurality of Arbitrated Loop Physical Addresses (ALPAs) of the plurality of FCAL nets;

using at least an ALPA of the OPN primitive to determine which of the plurality of ports a destination node identified in the OPN is coupled to and enable switching of data from the source node to the destination node;

communicating with the port coupled to the destination node to a select one of a plurality of separate channels through a switch unit and between a selectable pair of the plurality of ports;

establishing said channel for communication of primitives and data frames between said source node and said destination node; and

assigning a node a priority level for access to busy destination nodes and the priority level is escalated based on the number of consecutive denials.

12. The method of claim 11, wherein the channel is through a switch unit using at least one data path and the channel allows concurrent data transfers through the switch unit.

13. The method of claim 12, further comprising receiving a Fibre Channel data transfer on the virtual channel from the source node.

14. The method of claim 11, further comprising providing fairness of access to a switch on an individual port level to ensure a fraction of switch bandwidth is available.

15. The method of claim 11, further comprising:

arbitrating for control of a second FCAL net coupled to a port of the plurality of ports;

forwarding the OPN to the destination node when control of the second FCAL net is won following the arbitration;

receiving an Receive Ready (RRDY) primitive or a Close (CLS) primitive from the destination node and transmitting the primitive to the source node through the channel; and

continuing to pass data frames and primitives between the source node and destination node using Fibre Channel primitive messaging to provide flow control to indicate when to hold back and when to transmit data frames, until a CLS primitive is transmitted by either the source node or the destination node, and then closing the channel and relinquishing control of the FCAL net coupled to the port.

16. The method of claim 11, further comprising providing fairness of access to destination nodes based on attempts to establish communication with the destination node using a management logic.

17. The method of claim 11, further comprising providing testing information regarding a switch from a Joint Test Action Group (JTAG) circuit residing on the switch.

18. The method of claim 11, further comprising:

demultiplexing received encoded serial data and multiplexing outgoing data with a serializer/deserializer function coupled to at least one of the plurality of ports; and

absorbing differences between receive and transmit data rates on the at least one of the plurality of ports.

19. The method of claim 11, further comprising configuring switching functionality on a switch using a microprocessor.

20. The method of claim 11, further comprising:

communicating with a remote port on a separate switch using a multiplexed bus; and

establishing a virtual channel for each data flow allowing multiple data flows to be sent and received by the device on the multiplexed bus, wherein channels for communication on the multiplexed bus include data channels and at least one channel dedicated to other uses.