Method and apparatus for distributing USB hub functions across a network

• US 7,587,536 B2
• Filed: 07/28/2006
• Issued: 09/08/2009
• Est. Priority Date: 07/28/2006
• Status: Active Grant

• Current Assignee: Icron Technologies Corp. (Analog Devices, Inc.)
• Original Assignee: Icron Technologies Corp. (Analog Devices, Inc.)
• Inventors: McLeod, John Alexander
• Primary Examiner(s): Knoll; Clifford H
• Application Number:
  US11/460,963
• Publication Number:
  US 20080028120A1
• Time in Patent Office: 1,138 Days
• Field of Search: 370/466, 370401-402, 710313-315, 710/62, 710/65, 710/5
• US Class Current: 710/65
• CPC Class Codes: G06F 13/4045 where the bus bridge performs an extender function

Abstract

A method and related apparatuses for data transmission between a host computer and one or a plurality of USB compliant peripheral devices over a data communications network is provided which operates in the presence of transmission delays greater than that normally allowed in the USB specification. The host computer is connected to a local extender device which, in turn, is connected to one or a plurality of remote extender devices through the data communications network. The remote extender devices are, in turn, connected to a plurality of conventional USB peripheral devices. Data between the host computer and peripheral devices is stored and processed in the local and remote extender devices in order to allow the host computer and the USB peripheral devices to operate with greater than normally allowed time delays. In particular, the invention is of most utility when the round-trip transmission delay between the host computer and the USB peripheral device exceeds 1 microsecond.

Claims

1. A method for transmitting data between a host computer and one or a plurality of USB peripheral devices, wherein said USB peripheral devices are distributed around a data communications network and wherein the transmission delay across said network is greater than that normally allowed by the USB specification, said method comprising connecting a host computer to a local extender device, connecting said local extender device to one or a plurality of remote extender devices through a data communication network, and connecting said remote extender devices to one or a plurality of USB peripheral devices, wherein signals between said host computer and said USB peripheral devices are saved, collected, absorbed, or otherwise processed in the local extender and/or the remote extenders so as to allow the host computer and the USB peripheral devices to operate in the presence of a round trip delay greater than that normally allowed in the USB specification, and

wherein said method includes the ability to detect the attachment of a USB peripheral device to the system, to detect the detachment of a USB peripheral device, or includes the ability to determine the network address of a USB function wherein said USB function may be a USB hub or a USB peripheral device, and

wherein said method provides for transmitting a USB command from a host computer, through a local extender, to a unique network address on a data communications network, which method comprises:

a) receiving at a local extender a USB command from a host computer;

b) extracting a first USB address from said USB command;

c) using said first USB address to access a first data record within a table of similar records;

d) determining whether said first data record contains a valid network address;

e) extracting from said first data record a second USB address identifying the upstream USB hub through which said first USB address may be accessed;

f) repeating steps (c) through (e) until a valid network address is found;

g) encapsulating said USB command in a network packet;

h) addressing said network packet to said valid network address; and

i) transmitting said addressed network packet to said data communications network.

2. A method as claimed in claim 1 which includes the ability to detect the attachment of a USB peripheral device by a host computer, wherein said host computer and said USB peripheral device conform to the requirements of the USB Specification, through a local extender and a remote extender, which method comprises:

a) detecting at said remote extender a device attachment event, having said remote extender send a device connect signal to said local extender, and then having said local extender update its local record of the change in connection status of said USB peripheral device and its local record of the connected status of said USB peripheral device;

b) receiving at said local extender a request from said host computer for device status change information and having said local extender inform said host computer that the status of said USB peripheral device has changed;

c) receiving at said local extender a request from said host computer for the status of said USB peripheral device and having said local extender provide said local record of the change in connection status and said local record of connected status to said host computer;

d) receiving at said local extender a request from said host computer to clear said change in connection status information and having said local extender clear said local record of the change in connection status information;

e) receiving at said local extender a further request from said host computer for the status of said USB peripheral device and having said local extender provide said cleared local record of the change in connection status and said local record of connected status to said host computer;

f) receiving at said local extender a command from said host computer to reset said USB peripheral device, having said local extender send a reset signal to said remote extender, and then having said remote extender perform a physical reset on said USB peripheral device;

g) detecting at said remote extender the transmission speed of said USB peripheral device, having said remote extender send a speed signal to said local extender, and then having said local extender update its local record of the transmission speed of said USB peripheral device and its local record of the change in reset status of said USB peripheral device;

h) receiving at said local extender a further request from said host computer for device status change information and having said local extender inform said host computer that the status of said USB peripheral device has changed;

i) receiving at said local extender a yet further request from said host computer for the status of said USB peripheral device and having said local extender provide said local record of the transmission speed of said USB peripheral device and its local record of the change in reset status of said USB peripheral device to said host computer;

j) receiving at said local extender a request from said host computer to clear said change in reset status information and having said local extender clear said local record of the change in reset status information; and

k) receiving at said local extender a request from said host computer for the status of said USB peripheral device and having said local extender provide said cleared local record of the change in reset status to said host computer.

3. A method as claimed in claim 2 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.

4. A method as claimed in claim 1 which includes the ability to detect the detachment of a USB peripheral device by a host computer, wherein said host computer and said USB peripheral device conform to the requirements of the USB Specification, through a local extender and a remote extender, which method comprises:

a) detecting at said remote extender a device detachment event, having said remote extender send a device disconnect signal to said local extender, and then having said local extender update its local record of the change in connection status of said USB peripheral device and its local record of the connected status of said USB peripheral device;

b) receiving at said local extender a request from said host computer for device status change information and having said local extender inform said host computer that the status of said USB peripheral device has changed;

c) receiving at said local extender a request from said host computer for the status of said USB peripheral device and having said local extender provide said local record of the change in connection status and said local record of connected status to said host computer;

d) receiving at said local extender a request from said host computer to clear said change in connection status information and having said local extender clear said local record of the change in connection status information;

e) receiving at said local extender a request from said host computer to clear enabled status information of said USB peripheral device and having said local extender clear its local record of enabled status information; and

f) receiving at said local extender a further request from said host computer for the status of said USB peripheral device and having said local extender provide said cleared local record of the change in connection status and said cleared local record of enabled status to said host computer.

5. A method as claimed in claim 4 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.

6. A method as claimed in claim 1 which includes the ability to determine the network address of a USB function wherein said USB function may be a USB hub or a USB peripheral device, and wherein a plurality of said USB functions may be distributed around a data communications network, and wherein a USB address is allocated to each USB function by a host computer, which method comprises:

a) building a data record for each first USB function connected directly or indirectly to said network and identifying each record by a unique USB address assigned dynamically by said host computer;

b) recording within said data record the USB address of the upstream USB hub to which said first USB function is connected;

c) recording within said data record the port number of the upstream USB hub to which said first USB function is connected;

d) recording within said data record the USB address of each downstream USB function connected directly to said first USB function;

e) recording within said data record the port number of said first USB function to which each downstream USB function is connected; and

f) recording the network address assigned to said first USB function.

7. A method for transmitting data between a host computer and one or a plurality of USB peripheral devices, wherein said USB peripheral devices are distributed around a data communications network and wherein the transmission delay across said network is greater than that normally allowed by the USB specification, said method comprising connecting a host computer to a local extender device, connecting said local extender device to one or a plurality of remote extender devices through a data communication network, and connecting said remote extender devices to one or a plurality of USB peripheral devices, wherein signals between said host computer and said USB peripheral devices are saved, collected, absorbed, or otherwise processed in the local extender and/or the remote extenders so as to allow the host computer and the USB peripheral devices to operate in the presence of a round trip delay greater than that normally allowed in the USB specification, and

wherein said method provides for conducting asynchronous data transactions, between a host computer and a USB peripheral device, wherein said host computer operates at high-speed and said USB peripheral device operates at classic-speed (full-speed or low-speed), and wherein said data travels in a device to host direction, through a remote extender and a local extender, which method comprises:

a) receiving at a local extender a first request from said host computer for the start of a split data transfer session, having said local extender forward said first request across a network to said remote extender, and then having said local extender generate a negative acknowledgement response to said host computer;

b) receiving at a local extender a subsequent request from said host computer for the start of a split data transfer session and having said local extender continue to generate negative acknowledgement responses to said host computer until said local extender receives a response to said forwarded first request from said remote extender;

c) receiving at a remote extender said forwarded first request for the start of a split data transfer session, having said remote extender convert said forwarded request for the start of a split data transfer session into a classic-speed request for data transfer, and then having said remote extender forward said classic-speed request for data transfer to said USB peripheral device;

d) generating at a remote extender a positive acknowledgement response and forwarding said positive acknowledgement response across a network to said local extender;

e) receiving at a local extender said forwarded positive acknowledgement response and having said local extender store said forwarded positive acknowledgement response in local memory;

f) receiving at a local extender a further request from said host computer for the start of a split data transfer session, having said local extender retrieve from local memory said forwarded positive acknowledgement response, and then having said local extender forward said retrieved positive acknowledgement response to said host computer;

g) receiving at a remote extender a data transfer response from said USB peripheral device and having said remote extender generate a positive acknowledgement response to said USB peripheral device, and then having said remote extender forward said data transfer response across a network to said local extender;

h) receiving at a local extender a first request for completion of a split data transfer session, having said local extender check local memory for the absence of a data transfer response, and then having said local extender generate a not-yet acknowledgement to said host computer;

i) receiving at a local extender said forwarded data transfer response from said remote extender and having said local extender store said forwarded data transfer response in local memory; and

j) receiving at a local extender a further request for completion of a split data transfer session, having said local extender retrieve from local memory said forwarded data transfer response, and then having said local extender forward said retrieved data transfer response to said host computer.

8. A method as claimed in claim 7 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.

9. A method for transmitting data between a host computer and one or a plurality of USB peripheral devices, wherein said USB peripheral devices are distributed around a data communications network and wherein the transmission delay across said network is greater than that normally allowed by the USB specification, said method comprising connecting a host computer to a local extender device, connecting said local extender device to one or a plurality of remote extender devices through a data communication network, and connecting said remote extender devices to one or a plurality of USB peripheral devices, wherein signals between said host computer and said USB peripheral devices are saved, collected, absorbed, or otherwise processed in the local extender and/or the remote extenders so as to allow the host computer and the USB peripheral devices to operate in the presence of a round trip delay greater than that normally allowed in the USB specification, and

wherein said method provides for conducting asynchronous data transactions between a host computer and a USB peripheral device, wherein said host computer operates at high-speed and said USB peripheral device operates at classic-speed (full-speed or low-speed), and wherein said data travels in a host to device direction, through a local extender and a remote extender, which method comprises:

a) receiving at a local extender a first notification from said host computer for the start of a split data transfer session, having said local extender forward said first notification across a network to said remote extender, and then having said local extender generate a negative acknowledgement response to said host computer;

b) receiving at a local extender a subsequent notification from said host computer for the start of a split data transfer session and having said local extender continue to generate negative acknowledgement responses to said host computer until said local extender receives a response to said forwarded first notification from said remote extender;

c) receiving at a remote extender said forwarded first notification for the start of a split data transfer session, having said remote extender convert said forwarded notification for the start of a split data transfer session into a classic-speed notification for data transfer, and then having said remote extender forward said classic-speed notification for data transfer to said USB peripheral device;

d) generating at a remote extender a positive acknowledgement response and forwarding said positive acknowledgement response across a network to said local extender;

e) receiving at a local extender said forwarded positive acknowledgement response and having said local extender store said forwarded positive acknowledgement response in local memory;

f) receiving at a local extender a further notification from said host computer for the start of a split data transfer session, having said local extender retrieve from local memory said forwarded positive acknowledgement response, and then having said local extender forward said retrieved positive acknowledgement response to said host computer;

g) receiving at a remote extender a positive acknowledgement response from said USB peripheral device and having said remote extender forward said positive acknowledgement response across a network to said local extender;

h) receiving at a local extender a first request for completion of a split data transfer session, having said local extender check local memory for the absence of a positive acknowledgement response, and then having said local extender generate a not-yet acknowledgement to said host computer;

i) receiving at a local extender said forwarded positive acknowledgement response from said remote extender and having said local extender store said forwarded positive acknowledgement response in local memory; and

j) receiving at a local extender a further request for completion of a split data transfer session, having said local extender retrieve from local memory said forwarded positive acknowledgement response, and then having said local extender forward said retrieved positive acknowledgement response to said host computer.

10. A method as claimed in claim 9 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.

11. A method for transmitting data between a host computer and one or a plurality of USB peripheral devices, wherein said USB peripheral devices are distributed around a data communications network and wherein the transmission delay across said network is greater than that normally allowed by the USB specification, said method comprising connecting a host computer to a local extender device, connecting said local extender device to one or a plurality of remote extender devices through a data communication network, and connecting said remote extender devices to one or a plurality of USB peripheral devices, wherein signals between said host computer and said USB peripheral devices are saved, collected, absorbed, or otherwise processed in the local extender and/or the remote extenders so as to allow the host computer and the USB peripheral devices to operate in the presence of a round trip delay greater than that normally allowed in the USB specification, and

wherein said method provides for conducting isochronous data transactions between a host computer and a USB peripheral device, wherein said host computer operates at high-speed and said USB peripheral device operates at classic-speed (full-speed or low-speed), and wherein said data travels in a device to host direction, through a remote extender and a local extender, which method comprises:

a) receiving at a local extender a first request from said host computer for the start of a split data transfer session and having said local extender forward said first request for the start of a split data transfer session across a network to said remote extender;

b) receiving at a local extender a first request for completion of a split data transfer session, having said local extender check local memory for the absence of a complete sequence of split data transfer responses, and then having said local extender generate a null data response to said host computer;

c) receiving at a remote extender said forwarded first request for the start of a split data transfer session, having said remote extender convert said forwarded request for the start of a split data transfer session into a classic-speed request for data transfer, and then having said remote extender forward said classic-speed request for data transfer to said USB peripheral device;

d) receiving at a remote extender a data transfer response from said USB peripheral device and having said remote extender convert said received data transfer response into a sequence of split data transfer responses, and then having said remote extender forward said sequence of split data transfer responses across a network to said local extender;

e) receiving at a local extender said forwarded sequence of split data transfer responses from said remote extender and having said local extender store said forwarded sequence of split data transfer responses in local memory;

f) receiving at a local extender a subsequent request from said host computer for the start of a split data transfer session and having said local extender forward said subsequent request across a network to said remote extender; and

g) receiving at a local extender a sequence of subsequent requests for completion of a split data transfer session, having said local extender check local memory for the presence of a complete sequence of split data transfer responses, and then having said local extender retrieve said sequence of split data responses from memory and forward said sequence of split data responses to said host computer.

12. A method as claimed in claim 11 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.

13. A method for transmitting data between a host computer and one or a plurality of USB peripheral devices, wherein said USB peripheral devices are distributed around a data communications network and wherein the transmission delay across said network is greater than that normally allowed by the USB specification, said method comprising connecting a host computer to a local extender device, connecting said local extender device to one or a plurality of remote extender devices through a data communication network, and connecting said remote extender devices to one or a plurality of USB peripheral devices, wherein signals between said host computer and said USB peripheral devices are saved, collected, absorbed, or otherwise processed in the local extender and/or the remote extenders so as to allow the host computer and the USB peripheral devices to operate in the presence of a round trip delay greater than that normally allowed in the USB specification, and

wherein said method provides for conducting isochronous data transactions between a host computer and a USB peripheral device, wherein said host computer operates at high-speed and said USB peripheral device operates at classic-speed (full-speed or low-speed), and wherein said data travels in a host to device direction, through a local extender and a remote extender, which method comprises:

a) receiving at a local extender a notification from said host computer for the start of a split data transfer session, having said local extender forward said notification for the start of a split data transfer session across a network to said remote extender, and then having said remote extender store said notification for the start of a split data transfer session in local memory;

b) receiving at a local extender a first notification from said host computer for the continuation of a split data transfer session, having said local extender forward said first notification for the continuation of a split data transfer session across a network to said remote extender, and then having said remote extender store said first notification for the continuation of a split data transfer session in local memory;

c) receiving at a local extender a further notification from said host computer for the continuation of a split data transfer session, having said local extender forward said further notification for the continuation of a split data transfer session across a network to said remote extender, and then having said remote extender store said further notification for the continuation of a split data transfer session in local memory;

d) receiving at a local extender a notification from said host computer for the completion of a split data transfer session, having said local extender forward said notification for the completion of a split data transfer session across a network to said remote extender, and then having said remote extender store said notification for the completion of a split data transfer session in local memory;

e) assembling at a remote extender said stored notification for the start of a split data transfer, said stored first notification for the continuation of a split data transfer, said stored further notification for the continuation of a split data transfer and said stored notification for the completion of a split data transfer session into a classic-speed notification of data transfer; and

f) having said remote extender forward said classic-speed notification of data transfer to said USB peripheral device.

14. A method as claimed in claim 13 wherein said method operates over a data communications network in which the round-trip delay exceeds 1 microsecond.