Discovery, Detection, And Management Of Daisy-Chain System Topology

• US 20080155073A1
• Filed: 12/22/2006
• Published: 06/26/2008
• Est. Priority Date: 12/22/2006
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Swain, Tushara K.
• Granted Patent: US 7,782,800 B2
• Time in Patent Office: Days
• US Class Current: 709/222
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 12/42 Loop networks

Abstract

Devices and methods are disclosed for detection and management of daisy-chain system topologies. A method is disclosed for auto-discovery and auto-enumeration. The method may be performed in a daisy-chain system of serially inter-connected devices. The method may include identifying each port of each device in a system of serially inter-connected devices, discovering each device in the system, and enumerating each device in the system.

Claims

1. A method of auto-discovery and auto-enumeration, the method being performed in a daisy-chain system of serially inter-connected devices, the method comprising:

identifying each port of each device in a system of serially inter-connected devices;

discovering each device in the system; and

enumerating each device in the system.

2. The method of claim 1, further comprising:

detecting a topology change; and

propagating the topology change to each device in the daisy-chain system;

wherein the topology change comprises at least one of

     1) an additional device is added to the daisy-chain system,

     2) a device in the daisy-chain system is removed,

     3) a device in the daisy-chain system is powered on, and

     4) a device in the daisy-chain system is powered off.

3. The method of claim 1, further comprising managing the daisy-chain system by executing commands issued by any device in the daisy-chain system if the device has been granted use of a control token.

4. The method of claim 1, wherein identifying each port of each device further comprises:

detecting a link status change on one of the ports on one of the devices in the daisy-chain system; and

if a packet is received on the port having the link status change during a predetermined interval of time, defining the port as a boundary port.

5. The method of claim 4, if a packet is not received on the port during the predetermined interval of time, further comprising:

sending an auto-negotiation message to a neighboring device in the system;

if the same message is received in return from the neighboring device, defining the port as an internal port; and

if the same message is not received in return from the neighboring device, defining the port as a boundary port.

6. The method of claim 4, if a packet is not received on the port during the predetermined interval of time, further comprising:

changing content stored in an auto-negotiation register for the port in a predetermined sequence;

comparing the predetermined sequence to an advertised sequence of changes made to an auto-negotiation register for the connected port of a neighboring device;

if the sequences are the same, defining the port as an internal port; and

if the sequences are not the same, defining the port as a boundary port.

7. The method of claim 1, wherein discovering each device in the daisy-chain system further comprises generating and propagating a propagation packet.

8. The method of claim 7, wherein enumerating each device in the system further comprises:

assigning an identification number to the device of the second boundary port; and

at each device, assigning an identification number to each device that is one less than the identification number of the previous device in the system.

9. The method of claim 7, wherein enumerating each device in the system further comprises generating a discovery enumeration packet at the second boundary port device;

and

forwarding the enumeration packet to each device in the system until the enumeration packet is received by the first boundary port device.

10. The method of claim of claim 1, wherein discovering and enumerating each device is initiated by a master device in the system, wherein the master device is selected based on a comparison of the Media Access Control (“

MAC”

) addresses for the two boundary devices.

11. The method of claim 1, further comprising building a device list of the devices in the system and storing the device list locally on each device.

12. A device, comprising:

an ethernet switch having at least two ports;

a control logic operable to;

identify each of the ports as an internal port or a boundary port;

discover any device connected in a daisy-chain fashion to any identified internal port; and

enumerate any such discovered device connected in a daisy-chain fashion to any identified internal port.

13. The device of claim 12, wherein the control logic is further operable to:

detect a daisy-chain system topology change; and

propagate the daisy-chain system topology change to any device connected in a daisy-chain fashion to any identified internal port;

wherein the daisy-chain system topology change comprises at least one of

     1) an additional device is connected to a port identified as a boundary port, and

     2) a device is disconnected from a port identified as an internal port.

14. The device of claim 12, wherein in identifying each of the ports as an internal port or a boundary port, the control logic is further operable to:

detect a link status change on one of the ports; and

if a packet is received on the port during a predetermined interval of time, define the port as a boundary port.

15. The device of claim 14, wherein in identifying each of the ports as an internal port or a boundary port, the control logic is further operable to:

send an auto-negotiation message to a neighboring device;

if the same auto-negotiation message is received in return from the neighboring device, define the port as an internal port; and

if the same auto-negotiation message is not received in return from the neighboring device, define the port as a boundary port.

16. The device of claim 14, wherein in identifying each of the ports as an internal port or a boundary port, the control logic is further operable to:

change content stored in an auto-negotiation register for the port in a predetermined sequence;

compare the predetermined sequence to an advertised sequence of changes to an auto-negotiation register for a neighboring port of a neighboring device connected to the port of the device;

if the sequences are the same, define the port as an internal port; and

if the sequences are not the same, define the port as a boundary port.

17. The device of claim 12, wherein in discovering any device connected in a serial fashion to any identified internal port, the control logic is further operable to generate and propagate a propagation packet.

18. The device of claim 12, wherein in enumerating any such discovered device, the control logic is further operable to assign an identification number to the device where the identification number is equal to the total number of devices connected via an internal port if the device identifies at least one of its ports as a boundary port and the device is not a master device

19. The device of claim 12, wherein in enumerating any such discovered device, the control logic is further operable to assign an identification number to the device equaling one if the device identifies at least one of its ports as a boundary port and the device is a master device.

20. The device of claim 12, wherein in enumerating any such discovered device, the control logic is further operable to assign an identification number that is one less than the identification number of the most recent previously enumerated device in the system if the device identifies both of its ports as internal ports.

21. The device of claim 20, wherein in enumerating any such discovered device, the control logic is further operable to generate a discovery enumeration packet at any port identified as a boundary port, and forward the discovery enumeration packet to any device connected via an internal port.

22. A daisy-chain system, comprising:

a plurality of devices inter-connected together in a daisy-chain;

the boundaries of the system defined by a first boundary port of a first device in the system and a second boundary port of a second device in the system;

each device operable for auto-discovery and auto-enumeration, each device comprising;

an ethernet switch having at least two ports;

a control logic operable to;

identify each of the ports as an internal port or a boundary port;

discover any device connected in a daisy-chain fashion to any identified internal port; and

enumerate any such discovered device connected in a daisy-chain fashion to any identified internal port.

23. The daisy-chain system of claim 22, wherein the control logic is further operable to:

detect a topology change in the daisy-chain system; and

propagate the topology change to each device in the daisy-chain system;

wherein the topology change comprises at least one of

     1) an additional device is connected to the daisy-chain system,

     2) a device is disconnected from the daisy-chain system,

     3) a device in the daisy-chain system is powered on, and

     4) a device in the daisy-chain system is powered off.

24. The daisy-chain system of claim 22, wherein the control logic is further operable to:

detect a link status change on one of the ports;

if a packet is received on the port during a predetermined interval of time, define the port as a boundary port;

if a packet is not received on the port during the predetermined interval of time, implement at least one of the following auto-negotiation techniques;

1) send an auto-negotiation message to a neighboring device;

if the same message is received in return from the neighboring device, define the port as an internal port; and

if the same message is not received in return from the neighboring device, define the port as a boundary port; and

2) change content stored in an auto-negotiation register for the port in a predetermined sequence;

compare the predetermined sequence to an advertised sequence of changes to an auto-negotiation register for a neighboring port of a neighboring device connected to the port of the device;

if the sequences are the same, define the port as an internal port; and

if the sequences are not the same, define the port as a boundary port.

25. The daisy-chain system of claim 22, wherein the control logic is further operable to generate and forward a propagation packet to each device in the system, and generate and forward an enumeration packet to each device in the system.