SAS paired subtractive routing

• US 8,321,596 B2
• Filed: 04/02/2009
• Issued: 11/27/2012
• Est. Priority Date: 09/05/2008
• Status: Expired due to Fees

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Johnson, Stephen B., Parry, Owen, Petty, William K
• Primary Examiner(s): Tsai, Henry
• Assistant Examiner(s): Shyu, Jing-Yih
• Application Number:
  US12/384,288
• Publication Number:
  US 20100064060A1
• Time in Patent Office: 1,335 Days
• Field of Search: None
• US Class Current: 710/2
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence
• CPC Class Codes: G06F 13/4282 on a serial bus, e.g. I2C bus, SPI bus on daisy chain buses G06F13/4247

Abstract

An input port is assigned to a SAS expander device. An output port is assigned to the SAS expander device. The output port and the input port are defined to be paired with each other as a primary subtractive port. Only a SAS initiator address is programmed in the route table of the SAS expander. An OPEN command is sent out the output port upon receiving the OPEN command into the input port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device. An OPEN command is sent out the input port upon receiving the OPEN command into the output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device.

Claims

1. A method for performing paired subtractive routing in a Serial Attached Small Computer System Interface (SAS) cascaded topology, comprising:

assigning an input port to a SAS expander device;

assigning an output port to the SAS expander device;

defining the output port and the input port to be paired with each other as a primary subtractive port;

programming only a SAS initiator address in the route table of the SAS expander device;

adding a second input port and a second output port to the SAS expander device;

defining the second input port and the second output port to be paired with each other as a secondary subtractive port;

sending an OPEN command out the output port upon receiving the OPEN command into the input port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

sending the OPEN command out the input port upon receiving the OPEN command into the output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

sending the OPEN command out the second output port upon receiving the OPEN command into the second input port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

sending the OPEN command out the second input port upon receiving the OPEN command into the second output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device; and

specifying the subtractive ports of the SAS expander device via a modified routing attribute of a vendor unique SAS Management Protocol (SMP) function, wherein when the modified routing attribute exists for a port, a SAS initiator ignoring a SMP DISCOVER response attribute for the port and instead using the modified routing attribute for the port, the secondary subtractive port operates for communication with the direct attached device of the SAS expander device.

2. The method of claim 1, wherein the OPEN command defaults to the primary subtractive port.

3. The method of claim 1, wherein the programming a SAS initiator address in the route table of the SAS expander further includes:

programming the route table for a self-configuration specified port, wherein the programming the route table for the port is performed by the SAS expander device.

5. The method of claim 1, wherein the SAS initiator is located at a top or a bottom of the SAS routing topology.

4. A method for performing paired subtractive routing in a Serial Attached Small Computer System Interface (SAS) cascaded topology, comprising:

assigning an input port to a SAS expander device;

assigning an output port to the SAS expander device;

defining the output port and the input port to be paired with each other as a primary subtractive port;

programming only a SAS initiator address in the route table of the SAS expander device, wherein the programming the SAS initiator address in the route table of the SAS expander device further includes programming the SAS initiator address in the route table of the SAS expander device using each SAS initiator in a SAS routing topology, each SAS initiator programming only the SAS initiator address for that SAS initiator in the route table of the SAS expander device;

adding a second input port and a second output port to the SAS expander device;

defining the second input port and the second output port to be paired with each other as a secondary subtractive port;

sending an OPEN command out the output port upon receiving the OPEN command into the input port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device; and

sending the OPEN command out the input port upon receiving the OPEN command into the output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

specifying the subtractive ports of the SAS expander device via a modified routing attribute of a vendor unique SAS Management Protocol (SMP) function, wherein when the modified routing attribute exists for a port, a SAS initiator ignoring a SMP DISCOVER response attribute for the port and instead using the modified routing attribute for the port, wherein each SAS initiator only programs the SAS initiator address for that SAS initiator in the route table of one type of modified routing attribute port of the SAS expander device, depending on the position of the SAS initiator in the SAS routing topology.

6. A system, comprising:

means for assigning an input port to a SAS expander device;

means for assigning an output port to the SAS expander device;

means for defining the output port and the input port to be paired with each other as a primary subtractive port;

means for programming only a SAS initiator address in the route table of the SAS expander device;

means for adding a second input port and a second output port to the SAS expander device;

means for defining the second input port and the second output port to be paired with each other as a secondary subtractive port;

means for sending an OPEN command out the output port upon receiving the OPEN command into the input port if a DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

means for sending the OPEN command out the input port upon receiving the OPEN command into the output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

means for sending the OPEN command out the second output port upon receiving the OPEN command into the second input port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

means for sending the OPEN command out the second input port upon receiving the OPEN command into the second output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device; and

means for specifying the subtractive ports of the SAS expander via a modified routing attribute of a vendor unique SAS Management Protocol (SMP) function, wherein when the modified routing attribute exists for a port, a SAS initiator ignoring the SMP DISCOVER response attribute for the port and instead using the modified routing attribute for the port, the secondary subtractive port operates for communication with the direct attached device of the SAS expander device.

7. The system of claim 6, wherein the OPEN command defaults to the primary subtractive port.

8. The system of claim 6, wherein the means for programming the SAS initiator address in the route table of the SAS expander device further includes:

means for programming the route table for a self-configuration specified port, wherein the programming the route table for the port is performed by the SAS expander device.

9. A system, comprising:

means for assigning an input port to a SAS expander device;

means for assigning an output port to the SAS expander device;

means for defining the output port and the input port to be paired with each other as a primary subtractive port;

means for programming only a SAS initiator address in the route table of the SAS expander device, wherein the means for programming the SAS initiator address in the route table of the SAS expander device includes means for programming the SAS initiator address in the route table of the SAS expander device using a SAS initiator in the SAS routing topology, and wherein each SAS initiator programs only the SAS initiator address for that SAS initiator in the route table of the SAS expander device;

means for adding a second input port and a second output port to the SAS expander device;

means for defining the second input port and the second output port to be paired with each other as a secondary subtractive port;

means for sending an OPEN command out the output port upon receiving the OPEN command into the input port if a DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

means for sending the OPEN command out the input port upon receiving the OPEN command into the output port if the DEST of the OPEN command is not a direct attached device of the SAS expander device and the DEST is not in the route table of the SAS expander device;

means for specifying the subtractive ports of the SAS expander via a modified routing attribute of a vendor unique SAS Management Protocol (SMP) function, wherein when the modified routing attribute exists for a port, a SAS initiator ignoring the SMP DISCOVER response attribute for the port and instead using the modified routing attribute for the port, wherein each SAS initiator only programs the SAS initiator address for that SAS initiator in the route table of one type of modified routing attribute port of the SAS expander device, depending on the position of the SAS initiator in the SAS routing topology.

10. The system of claim 9, wherein a SAS initiator is located at a top or a bottom of the SAS routing topology.