LOSSLESS SWITCHING OF TRAFFIC IN A NETWORK DEVICE

• US 20150081865A1
• Filed: 11/05/2013
• Published: 03/19/2015
• Est. Priority Date: 09/17/2013
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: KOSTIC, Predrag, NEUMAN, Darren Duane, WU, David, TONGLE, Anand, MAMIDWAR, Rajesh Shankarrao, ALEKSIC, Milomir
• Granted Patent: US 10,404,624 B2
• Time in Patent Office: Days
• US Class Current: 709/223
• CPC Class Codes: H04L 49/505 Corrective measures

Abstract

A system for lossless switching of traffic in a network device may be implemented when a network switch is integrated into a gateway device, or with any other data source. A processor of the gateway device may receive queue depth information for queues of the network switch. The processor may prevent data from being transmitted to congested queues of the network switch, while allowing data to be transmitted to uncongested queues. In this manner, data loss can be avoided through the network switch for data sourced from the gateway device, such as audio-video data retrieved from a hard drive, audio-video data received from a tuner, etc. Furthermore, re-transmission at higher layers can be reduced. Since the subject system observes congestion for each individual queue, only traffic destined to that particular, congested, queue is affected, e.g. paused. Traffic to non-congested queues is not affected, regardless of traffic class or egress port.

Claims

1. A system for lossless switching of traffic in a network device, the system comprising:

a network device comprising queues;

a data source comprising data items, each of the data items being associated with one of the queues; and

a processor that is communicably coupled to the data source and the network device, and that is configured to;

receive queue depth information for each of the queues of the network device; and

release at least one of the data items to the network device when the queue depth information indicates that the associated queue can accommodate the at least one of the data items, irrespective of the queue depth information for the other queues.

2. The system of claim 1, wherein the processor is configured to release the at least one of the data items to the network device when the queue depth information indicates that the associated queue can accommodate the at least one of the data items and the queue depth information indicates that at least one of the other queues cannot accommodate the at least one of the data items.

3. The system of claim 1, wherein the network device further comprises ports and each of the queues is associated with one of the ports.

4. The system of claim 1, wherein the processor comprises a first module and the network device comprises a second module, the first module being configured to:

receive an indication of an intent to release the at least one of the data items to the network device, wherein the indication comprises a size of the at least one of the data items;

transmit the size of the one of the data items and an identifier of the associated queue to the second module of the network device;

receive the queue depth information for each of the queues of the network device from the second module of the network device, wherein the queue depth information is indicative of whether each of the queues can accommodate the at least one of the data items; and

determine whether to allow the at least one of the data items to be released to the network device based at least on the queue depth information for the associated queue and irrespective of the queue depth information for the other queues.

5. The system of claim 4, wherein each of the data items is associated with one of a plurality of channels, each of the plurality of channels is associated with one of the queues of the network device.

6. The system of claim 5, wherein each of the plurality of channels is associated with an indicator that indicates whether the data items associated with each of the plurality of channels should be released, and the system further comprising:

an arbiter that arbitrates the release of the data items for each of the plurality of channels, wherein the arbiter determines whether to consider each of the plurality of channels for release based at least in part on the indicator associated with each of the plurality of channels.

7. The system of claim 4, further comprising:

a packetization pipeline communicably coupled to the data source and the network device, wherein the at least one of the data items is released from the data source to the packetization pipeline and is passed from the packetization pipeline to the network device.

8. The system of claim 7, further comprising:

a tap that is located between an end of the packetization pipeline and the network device, wherein the tap is configured to transmit an indication of the at least one of the data items to the first module when the at least one of the data items passes through the tap.

9. The system of claim 8, wherein the first module is further configured to transmit the indication of the at least one of the data items to the second module of the network device upon receiving the indication of the at least one of the data items from the tap.

10. The system of claim 4, wherein the data items comprise packets, the first module and the second module are on a single semiconductor chip, the first module is communicably coupled to the second module via a transmission line on the semiconductor chip, and the data source is stored on a memory module that is external to the semiconductor chip.

11. A switch device comprising:

a first ingress port that is associated with audio video (AV) traffic, and a second ingress port that is associated with non-AV traffic;

a plurality of egress ports, each of the plurality of egress ports being associated with a plurality of queues, at least one of the plurality of queues of each of the plurality of egress ports being dedicated to the audio video (AV) traffic of the first ingress port and at least one of the plurality of queues of each of the plurality of egress ports being dedicated to the non-AV traffic of the second ingress port; and

a plurality of schedulers that each schedules the plurality of queues associated with one of the plurality of ports for transmission over the one of the plurality of ports, wherein the at least one of the plurality of queues that is dedicated to the AV traffic of each of the plurality of ports is scheduled with a higher scheduling priority than the at least one of the plurality of queues of each of the plurality of ports that is dedicated to the non-AV traffic.

12. The switch device of claim 11, wherein the first ingress port is associated with AV traffic and non-AV traffic.

13. The switch device of claim 11, wherein the AV traffic is received over the first ingress port and is queued in the at least one queue that is dedicated to the AV traffic associated with one of the plurality of egress ports, and the non-AV traffic is received over the second ingress port and is queued in the at least one queue that is dedicated to the non-AV traffic associated with one of the plurality of egress ports.

14. The switch device of claim 11, further comprising

a first module that is configured to monitor queue depths associated with each of the plurality of queues that is dedicated to the AV traffic and to maintain an in-flight variable for each of the plurality of queues that is dedicated to the AV traffic.

15. The switch device of claim 14, wherein the first module is further configured to:

receive a request to release a data unit to the switch device, wherein the request comprises a size of the data unit and an identifier of one of the plurality of queues that is associated with the data unit;

determine whether the one of the plurality of queues can accommodate the data unit based at least in part on the queue depth of the one of the plurality of queues, the in-flight variable of the one of the plurality of queues, and the size of the data unit; and

transmit an indication of whether the one of the plurality of queues can accommodate the data unit.

16. The switch device of claim 15, wherein the first module is further configured to:

add the size of the data unit to the in-flight variable of the one of the plurality of queues upon receiving the request; and

subtract the size of the data unit from the in-flight variable of the one of the plurality of queues upon receiving an indication that the data unit has been transmitted to the switch device.

17. The switch device of claim 15, wherein the first module is configured to receive the request to release the data unit from a second module that is communicably coupled to a data source storing the data unit, the first module and the second module being collocated on an integrated circuit.

18. A computer program product comprising instructions stored in a tangible computer-readable storage medium, the instructions comprising:

instructions for receiving an indication of intent to release a packet from a data source, the indication comprising a packet size and an identifier of a queue of a switch device;

instructions for determining whether space is available for the packet in a portion of a buffer that is allocated to the queue of the switch device based at least in part on the packet size, a queue depth of the queue, and a variable that is indicative of whether other data units associated with the queue are in-transit; and

instructions for allowing the packet to be scheduled for release from the data source when the space is available for the packet; and

instructions for preventing the packet from being scheduled for release from the data source when the space is not available for the packet.

19. The computer program product of claim 18, further comprising:

instructions for adding the packet size to the variable that is indicative of whether other data units associated with the queue are in-transit; and

instructions for removing the packet size from the variable when the packet is received at the switch device.

20. The computer program product of claim 18, wherein the instructions for determining whether the space is available for the packet in the portion of the buffer that is allocated to the queue further comprises:

instructions for determining a current space available in the portion of the buffer that is allocated to the queue based at least in part on the queue depth;

instructions for determining an amount of the current space available that is required to store the other data units associated with the queue that are in-transit based at least in part on the variable that is indicative of whether other data units associated with the queue are in-transit; and

instructions for determining whether the space is available for the packet based at least in part on whether the packet size is less than or equal to a remaining amount of the current space available after accounting for the amount of the current space available required to store the other data units associated with the queue that are in-transit.