Apparatus and method for data transmission

• US 8,352,571 B2
• Filed: 08/31/2009
• Issued: 01/08/2013
• Est. Priority Date: 05/26/1999
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Kaneko, Michio
• Primary Examiner(s): BAROT, BHARAT
• Application Number:
  US12/551,342
• Publication Number:
  US 20090316726A1
• Time in Patent Office: 1,226 Days
• Field of Search: 709217-219, 709225-228, 370229-235, 370/468
• US Class Current: 709/217
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5649 Cell delay or jitter
• CPC Class Codes: H04L 2012/565 Sequence integrity
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04L 49/60 Software-defined switches

Abstract

Local concentration of accessing loads on a data buffer during data cell reading is reduced. Also, by providing sufficient time for a data cell reading operation with respect to data cell transmission timing, transmission rate fluctuation of CBR data cells in a transmitting side is reduced. When transmission of a new data stream is added, controller in a cell control unit refers to a transmitted data cell count of VC information processed through a slot immediately before. The controller determines whether a data cell transmitted through the slot immediately before is a head portion of a packet or not. If the data cell transmitted through the slot immediately before is the head portion of the packet, the controller only adds the VC information of the data stream to a shaper link list, and withholds transmission of the data cell. On the other hand, if the data cell transmitted through the slot immediately before is not the head portion of the packet, then the controller adds the VC information of the data stream, and transmits the data cell.

Claims

1. A network device comprising:

a controller to;

determine whether a first header of a first data packet is transmitted from the network device in a first time slot in a transmission cycle,

determine that a second header of a second data packet, that is different from the first header is to be transmitted from the network device in a second time slot of the transmission cycle, the second time slot being adjacent to the first time slot in the transmission cycle,

transmit the second header from the network device in the second time slot when the first header is not transmitted in the first time slot, and

delay a transmission of the second header to a subsequent transmission cycle when the first header is transmitted from the network device in the first time slot of the transmission cycle.

2. The network device of claim 1, where the controller is further to:

store, in a memory associated with the network device, a data stream to be transmitted from the network device,

where the data stream is divided into the first data packet and the second data packet, the first data packet comprising the first header and a first data portion and the second data packet comprising the second header and a second data portion, and

where the first data packet and the second data packet are each to be transmitted sequentially as a plurality of data cells.

3. The network device of claim 2, where the controller is further to:

prior to transmitting the first header, identify the first header and the first data portion of the first data packet, and

identify the second header and the second data portion of the second data packet.

4. The network device of claim 1, where the controller is further to:

transmit the first header of the first data packet from the network device in the first time slot of the transmission cycle when data transmitted from the network device immediately prior to the first header being read comprises a data portion of a third data packet.

5. The network device of claim 1, where the controller is further to:

transmit the first header of the first data packet from the network device in a second time slot of the subsequent transmission cycle when the first header is transmitted from the network device in the first time slot of the transmission cycle.

6. The network device of claim 1, where, when delaying the transmission of the second header of the second data packet, the controller is further to:

determine a transmission of a last portion of the first data packet from the network device, and

delay the transmission of the second header of the second data packet from the network device until after the transmission of the last portion of the first data packet from the network device.

7. The network device of claim 1, where, when determining whether the first header of the first data packet is transmitted from the network device in the first time slot, the controller is further to:

determine whether a counter associated with the first data packet comprises a particular value, and

determine that the first header of the first data packet is transmitted from the network device when the counter comprises the particular value.

8. A non-transitory computer-readable medium comprising:

one or more instructions which, when executed by a processor of a network device, cause the processor to determine whether a first header portion of a first data packet is transmitted from the network device in a first slot of a transmission cycle;

one or more instructions which, when executed by the processor of the network device, cause the processor to determine that a second header portion of a second data packet, that is different from the first header portion, is to be transmitted from the network device in a second slot of the transmission cycle that is adjacent to the first slot in the transmission cycle;

one or more instructions which, when executed by the processor, cause the processor to transmit the second header portion from the network device in the second slot when the first header portion is not transmitted in the first slot; and

one or more instructions which, when executed by the processor, cause the processor to delay a transmission of the second header portion to a slot of a subsequent transmission cycle when the first header portion of the first data packet is transmitted from the network device in the first slot of the transmission cycle.

9. The non-transitory computer-readable medium of claim 8, where the instructions further comprise:

one or more instructions to store the data stream in a data buffer portion of a memory associated with the network device.

10. The non-transitory computer-readable medium of claim 8, where the instructions further comprise:

one or more instructions to determine that the second data packet is entirely outputted to the network; and

where the one or more instructions to delay the transmission of the second header portion to the slot of the subsequent transmission cycle, further comprise;

one or more instructions to delay transmitting the second header portion of the second data packet until after the network device determines that the first data packet is entirely outputted to the network.

11. The non-transitory computer-readable medium of claim 8, the instructions further comprising:

one or more instructions to determine whether the first header portion or a first non-header portion of the first data packet is to be transmitted from the slot of the transmission cycle; and

one or more instructions to determine whether a header portion or a non-header portion of a third data packet is to be transmitted from the network device immediately prior to the data of the first data packet being read, the data of the first data packet being transmitted in the first time slot of the first transmission cycle when the non-header portion of the third data packet is transmitted from the network device immediately prior to the data of the first data packet being read.

12. The non-transitory computer-readable medium of claim 8, where the one or more instructions which, when executed by the processor, cause the processor to determine whether the first header portion of the first data packet is transmitted from the network device in the first slot of the transmission cycle include:

one or more instructions which, when executed by the processor, cause the processor to;

determine whether a counter associated with the first data packet comprises a particular value, and

determine that the first header portion of the first data packet is transmitted from the network device when the counter comprises the particular value.

13. A method comprising:

transmitting, by a network device and immediately prior to reading data of a second data packet from a memory of the network device, data of a first data packet in a first time slot of a first transmission cycle;

determining, by the network device, whether the transmission of the data of the first data packet satisfies a first condition associated with the transmission of the first data packet;

determining, by the network device, whether the data of the second data packet, that is to be transmitted in a second time slot of the first transmission cycle, satisfies a second condition, the second time slot immediately following the first time slot in the first transmission cycle and the second condition corresponding to the transmission of the data of the second data packet;

transmitting, by the network device, the data of the second data packet in the second time slot of the first transmission cycle when the data of the first data packet does not satisfy the first condition or the data of the second data packet does not satisfy the second condition; and

transmitting, by the network device, the data of the second data packet in a time slot of a second transmission cycle when the data of the first data packet satisfies the first condition and the data of the second data packet satisfies the second condition.

14. The method of claim 13, further comprising:

preventing, by the network device, a transmission of the data of the second data packet in the second time slot of the first transmission cycle when the data of the first data packet satisfies the first condition and the data of second the data packet satisfies the second condition.

15. The method of claim 13, where the first condition is satisfied when the data of the first data packet comprises a header portion of the first data packet and the second condition is satisfied when the data of the second data packet comprises a header portion of the second data packet.

16. The method of claim 13, further comprising:

transmitting, by the network device, the data of the second data packet after transmission of a last portion of the first data packet when the data of the first data packet does not satisfy the first condition or the data of the second data packet does not satisfy the second condition.

17. The method of claim 13, further comprising:

transmitting, by the network device, a last portion of the first data packet in a first time slot of the second transmission cycle; and

transmitting, by the network device, the data of the second data packet in a time slot of another transmission cycle when the data of the first data packet satisfies the first condition and the data of the second data packet satisfies the second condition, the other transmission cycle beginning after the transmission of the last portion of the first data packet.

18. The method of claim 13, further comprising:

incrementing, based on transmitting the data of the first data packet, a counter; and

where determining whether the transmission of the data of the first data packet satisfies the first condition includes;

determining whether the incremented counter comprises a particular value, the transmission of the data of the first data packet satisfying the first condition when the incremented counter comprises the particular value.