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

• US 7,471,691 B2
• Filed: 01/21/2003
• Issued: 12/30/2008
• Est. Priority Date: 01/23/1997
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Black, Alistair D., Chan, Kurt
• Primary Examiner(s): Pham; Chi H.
• Assistant Examiner(s): TRAN, PHUC H
• Application Number:
  US10/348,687
• Publication Number:
  US 20030198251A1
• Time in Patent Office: 2,170 Days
• Field of Search: None
• 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. A packet switching switch for coupling a plurality of node loop (NL) nodes and/or Fibre Channel Arbitrated Loop network (FCAL nets) together to all concurrent data exchanges between a plurality of pairs comprised of one NL node or FCAL net and one other NL node or FCAL net, comprising:

a crossbar switch;

a protocol bus;

a plurality of port circuits each having an input and an output for connecting to an FCAL net coupled to one or more NL nodes and capable of implementing a Fibre Channel loop protocol, and each having a crossbar switch port coupled to said crossbar switch;

means coupled to said protocol bus for maintaining a scoreboard table containing at least status information and a routing table either centrally located or in each port circuit, said routing table containing data mapping destination addresses of NL nodes to port IDs;

and wherein said port circuits are coupled to said means for maintaining a scoreboard table and routing table and wherein said port circuits function to establish connections between themselves by using destination addresses in (Open) OPN primitives received from source nodes to search said routing table to determine the ID of a remote port coupled to the destination node having the destination address in the OPN and, using that port ID to search said scoreboard table to determine status of the remote port, and then exchanging messages with said remote port to cause it to arbitrate for and take control of its local FCAL net and establish a particular channel through said crossbar switch and use said channel to transmit primitives and data frames between said source node and said destination node.

2. The packet switching switch of claim 1 where said switch is structured to be capable of operating at high throughput rate, but neither said crossbar switch nor said port circuits have the amount of memory that would be needed in a fabric switch to operate at the same throughput rate.

3. The packet switching switch of claim 1 wherein said port circuits are not FL_ports.

4. The packet switching switch of claim 1 wherein said port circuits have no error recovery protocols and are structured to use hold back flow control such that frames are not transmitted until the connection is established through said crossbar switch to the destination node and is ready to stream the data directly from the source node to the destination node without ever buffering the data and never dropping a frame.

5. The packet switching switch of claim 1 wherein each said port circuit is structured to use the destination address tag of an FCAL net OPN primitive as a routing address and search key to search said routing table of destination addresses and structured to establish and update the contents of said routing table by learning the locations of destination nodes by watching traffic passing through said port, said routing table comprising a destination address and the ID of the particular port to which data and primitives of an FCAL loop tenancy are to be sent to communicate with the NL node having that destination address, said port circuits also structured to use the routing information derived from said search to search said scoreboard table and exchange messages with said remote port over a protocol bus to cause said remote port to begin arbitrating and to select a particular data path through said crossbar switch and to control switching by said crossbar switch to establish the selected data path.

6. The packet switching switch of claim 1 wherein said crossbar switch is distributed and a portion of it is integrated together with one or more of said port circuits on a single integrated circuit die.

7. A packet switch for coupling a plurality of node loop (NL) nodes and/or Fibre Channel Arbitrated Loop network (FCAL nets) together to all concurrent data exchanges between a plurality of pairs comprised of one NL node or FCAL net and one other NL node or FCAL net, comprising:

a crossbar switch;

a protocol bus;

a plurality of port circuits each having an input and an output for connecting to an FCAL net coupled to one or more NL nodes and capable of implementing a Fibre Channel loop protocol, and each having a crossbar switch port coupled to said crossbar switch;

circuitry in each said port circuit and coupled to said protocol bus for maintaining a scoreboard table containing at least status information and a routing table containing data mapping destination addresses of NL nodes to port IDs;

and wherein said port circuits function to establish connections between themselves by using destination addresses in Open (OPN) primitives received from source nodes to search said routing table to determine the ID of a remote port coupled to the destination node having the destination address in the OPN and, using that port ID to search said scoreboard table to determine status of the remote port, and then exchanging messages with said remote port to cause it to arbitrate for and take control of its local FCAL net and establish a data path via a particular channel through said crossbar switch and use said channel to transmit primitives and data frames between said source node and said destination node.

8. The packet switch of claim 7 wherein each said port circuit includes means for storing and updating the contents of said routing table using a passive learning process by watching traffic through the port.

9. The packet switch of claim 7 wherein each said port circuit includes means for storing and updating the contents of said routing table using an active discovery process of sending out inquiries to all nodes on the network.

10. A packet switching switch for coupling a plurality of node loop (NL) nodes and/or Fibre Channel Arbitrated Loop network (FCAL nets) together to all concurrent data exchanges between a plurality of pairs comprised of one NL node or FCAL net and one other NL node or FCAL net, comprising:

a crossbar switch;

a protocol bus;

a plurality of port circuits each having an input and an output for connecting to an FCAL net coupled to one or more NL nodes and capable of implementing a Fibre Channel loop protocol, and each having a crossbar switch port coupled to said crossbar switch;

circuitry in each said port circuit and coupled to said protocol bus for maintaining a routing table containing data mapping destination addresses of NL nodes to port IDs and for maintaining a scoreboard table containing at least status information of remote ports;

and wherein said port circuits function to establish connections between themselves by latching any Open (OPN) and Ready (RRDY) primitives received from source nodes and using destination addresses in OPN primitives received from said source nodes to search said routing table to determine the ID of a remote port coupled to the destination node having the destination address in the OPN, and then establishing a data path through said crossbar switch to said remote port and wherein each said port when it receives an OPN and any following RRDYs from another port via said crossbar switch, functioning to latch said OPN and RRDY and arbitrate for and take control of its local FCAL net, and

continuing to try to take control of its local FCAL net until control is achieved, and when control is achieved, sending said OPN and any latched RRDYs to the destination node, and thereafter using said data path through said crossbar switch to send primitives and data frames back and forth between said source and destination nodes until the transaction is completed without ever storing any data frames.

11. The packet switching switch of claim 10 wherein each said port circuit includes means for storing and updating the contents of said routing table using a passive learning process by watching traffic through the port.