Single counter for controlling multiple finite state machines in a multi-port bridge for local area network

• US 6,252,879 B1
• Filed: 05/13/1998
• Issued: 06/26/2001
• Est. Priority Date: 09/17/1997
• Status: Expired due to Fees

• Current Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.), Sony Electronics Inc. (Sony Group Corp.)
• Inventors: Zhang, Erica
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): JONES, PRENELL P
• Application Number:
  US09/078,412
• Time in Patent Office: 1,140 Days
• Field of Search: 370/479, 370/466, 370/400, 370/402, 370/401, 370/239, 370/395, 370/404, 370/403, 370/331, 370/338, 370/436, 370/456, 370/452, 370/240, 370/407, 370/446, 370/502, 709/242, 709/149, 709/223, 709/243, 709/227-229, 709/238, 709/222, 375/241, 375/272, 375/295
• US Class Current: 370/401
• CPC Class Codes: H04L 12/4625 Single bridge functionality, e.g. connection of two networks over a single bridge
• CPC Class Codes: H04L 49/102 using shared medium, e.g. bus or ring
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches

Abstract

A multi-port bridge includes a plurality of ports interconnected by a communication bus. A memory device, utilized for temporarily storing packets to be bridged by the multi-port bridge, is accessed by each port via the communication bus. A memory pointer for each packet to be transmitted by a port is stored in a memory pointer buffer within the port. The memory pointer includes an address assigned to the packet in the memory device. Each port includes: a first finite state machine (transmit FSM) which controls retrieving packets from the memory device and transmitting the packets to the network segment associated with the port; a second FSM (memory pointer FSM) which controls receiving memory pointers from the communication bus and storing the memory pointers in the memory pointer buffer; and a third FSM (receive FSM) which controls receiving packets from the network segment associated with the port and storing the packets in the memory device. Each FSM requires a set of registers, including a counter for keeping track of the current state of the FSM and registers for storing parameters utilized by the FSM. At any time, none, one, two or all of the FSMs in a port can be active. At least one register is identified that is used only in certain states in each of the FSMs such that no more than one FSM requires use of this register at the same time. Accordingly, each of the three FSMs share at least one register.

Claims

1. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. means for controlling transmittal of packets from the port to an associated network segment;

b. means for controlling receiving packets into the port from the associated network segment; and

c. a first shared register wherein, at different times, the means for controlling transmittal of packets utilizes the first shared register for storing a first operational parameter and the means for controlling receiving packets utilizes the first shared register for storing a second operational parameter.

2. The multi-port bridge according to claim 1 further comprising a second shared register wherein, at different times, the means for controlling transmittal of packets utilizes the second shared register for storing a third operational parameter and the means for controlling receiving packets utilizes the second shared register for storing a fourth operational parameter.

3. The multi-port bridge according to claim 1 further comprising:

a. a means for controlling storage of memory pointers indicative of an assigned location in a memory device for each packet; and

b. a second shared register wherein, at different times, the means for controlling transmittal of packets utilizes the second shared register for storing a third operational parameter and the means for controlling storage of memory pointers utilizes the second shared register for storing a fourth operational parameter.

4. The multi-port bridge according to claim 1 further comprising:

a. a means for controlling storage of memory pointers indicative of an assigned location in a memory device for each packet; and

b. a second shared register wherein, at different times, the means for controlling receiving packets utilizes the second shared register for storing a third operational parameter and the means for controlling storage of memory pointers utilizes the second shared register for storing a fourth operational parameter.

5. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. a register;

b. a transmit finite state machine to control retrieval of packets from an assigned location for each packet in a memory device wherein the transmit finite state machine utilizes the register for storing an operational parameter of the transmit finite machine; and

c. a receive finite state machine to control storage of packets in the memory device at the assigned location for each packet wherein the receive finite state machine utilizes the register for storing an operational parameter of the receive finite state machine.

6. The multi-port bridge according to claim 5 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine and the receive finite state machine stores an operational parameter in the register.

7. The multi-port bridge according to claim 5 further comprising a memory pointer finite state machine to control storage of memory pointers indicative of the assigned location in the memory device for each packet wherein the memory pointer finite state machine utilizes the register for storing an operational parameter of the memory pointer finite state machine.

8. The multi-port bridge according to claim 7 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine, the receive finite state machine and the memory pointer finite state machine stores an operational parameter in the register.

9. The multi-port bridge according to claim 7 wherein each memory pointer includes an identification number and an address indicative of the assigned location in the memory device.

10. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. a register;

b. a receive finite state machine to control storage of packets in the memory device at an assigned location for each packet wherein the receive finite state machine utilizes the register for storing an operational parameter of the receive finite state machine; and

c. a memory pointer finite state machine to control storage of memory pointers indicative of the assigned location in the memory device for each packet wherein the memory pointer finite state machine utilizes the register for keeping track of an operational parameter of the memory pointer finite state machine.

11. The multi-port bridge according to claim 10 wherein at all points in time during operation of the multi-port bridge, not more than one of the receive finite state machine and the memory pointer finite state machine stores an operational parameter in the register.

12. The multi-port bridge according to claim 10 wherein each memory pointer includes an identification number and an address indicative of the assigned location in the memory device.

13. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. a register;

b. a transmit finite state machine to control retrieval of packets from an assigned location for each packet in a memory device wherein the transmit finite state machine utilizes the register for storing an operational parameter of the transmit finite machine; and

c. a memory pointer finite state machine to control storage of memory pointers indicative of the assigned location in the memory device for each packet wherein the memory pointer finite state machine utilizes the register for keeping track of an operational parameter of the memory pointer finite state machine.

14. The multi-port bridge according to claim 13 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine and the memory pointer finite state machine stores an operational parameter in the register.

15. The multi-port bridge according to claim 13 wherein each memory pointer includes an identification number and an address indicative of the assigned location in the memory device.

16. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. a register;

b. a transmit finite state machine to control transmission of packets to a segment of the local area network associated with the port wherein the transmit finite state machine utilizes the register for storing an operational parameter of the transmit finite machine; and

c. a receive finite state machine to control reception of packets from the segment of the local area network associated with the port wherein the receive finite state machine utilizes the register for storing an operational parameter of the receive finite state machine.

17. The multi-port bridge according to claim 16 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine and the receive finite state machine stores an operational parameter in the register.

18. A method of controlling a port in a multi-port bridge wherein the multi-port bridge interconnects a plurality of segments of a local area network via a plurality of ports, the method comprising steps of:

a. providing a register in the port;

b. storing an operational parameter for a transmit finite machine in the register wherein the transmit finite state machine controls transmittal of packets from the port to an associated network segment; and

c. storing an operational parameter for a receive finite machine in the register wherein the receive finite state machine controls receiving packets into the port from the associated network segment.

19. The method according to claim 18 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine and the receive finite state machine stores an operational parameter in the register.

20. The method according to claim 18 further comprising a step of storing an operational parameter for a memory pointer finite state machine in the register wherein the memory pointer finite state machine controls storage of memory pointers indicative of an assigned location in a memory device.

21. The method according to claim 20 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine, the receive finite state machine and the memory pointer finite state machine stores an operational parameter in the register.

22. The method according to claim 20 wherein each memory pointer includes an identification number and an address indicative of the assigned location in the memory device.

23. A multi-port bridge for interconnecting a plurality of segments of a local area network, the multi-port bridge having a plurality of ports, at least one of the ports comprising:

a. a register;

b. a transmit finite state machine to control transmittal of packets from the port to an associated network segment wherein the transmit finite state machine utilizes the register for storing an operational parameter of the transmit finite machine; and

c. a receive finite state machine to control receiving packets into the port from the associated network segment wherein the receive finite state machine utilizes the register for storing an operational parameter of the receive finite state machine.

24. The multi-port bridge according to claim 23 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine and the receive finite state machine stores an operational parameter in the register.

25. The multi-port bridge according to claim 23 further comprising a memory pointer finite state machine to control storage of memory pointers indicative of an assigned location in a memory device for each packet wherein the memory pointer finite state machine utilizes the register for storing an operational parameter of the memory pointer finite state machine.

26. The multi-port bridge according to claim 25 wherein at all points in time during operation of the multi-port bridge, not more than one of the transmit finite state machine, the receive finite state machine and the memory pointer finite state machine stores an operational parameter in the register.

27. The multi-port bridge according to claim 25 wherein each memory pointer includes an identification number and an address indicative of the assigned location in the memory device.