Queuing closed loop congestion mechanism

• US 20030165148A1
• Filed: 03/01/2002
• Published: 09/04/2003
• Est. Priority Date: 03/01/2002
• Status: Active Grant

• Current Assignee: Verizon Patent and Licensing Incorporated (Verizon Communications Inc.)
• Original Assignee: Verizon Business Global LLC (Verizon Communications Inc.)
• Inventors: Bishard, Clint J.
• Granted Patent: US 7,362,749 B2
• Time in Patent Office: Days
• US Class Current: 370/412
• CPC Class Codes: H04L 2012/5671 Support of voice
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/22 Traffic shaping
• CPC Class Codes: H04L 47/2441 relying on flow classification, e.g. using integrated services [IntServ]
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/30 in combination with information about buffer occupancy at either end or at transit nodes
• CPC Class Codes: H04L 47/32 by discarding or delaying data units, e.g. packets or frames

Abstract

An exemplary queuing congestion mechanism and method are disclosed that provide congestion management at an egress port of a packet switch. The queuing congestion mechanism includes at least a first, a second and a third queue, which each have an input, an output, and a capacity. Each queue is operable to receive packets of information of a designated type, such as a service category type, at its input that are destined to be communicated to the egress port through its output. The queuing congestion mechanism further includes a scheduler and a queue shaper. The scheduler, which may be implemented as a strict scheduler, is operable to receive the packets of information from the output of the queues and to communicate the packets of information to the egress port of the packet switch based on a schedule. The queue shaper is operable to set an adjustable rate in which the packets of information of the third queue are communicated to the scheduler, and the adjustable rate is controlled by a loading of the capacity of the second queue. The queuing congestion mechanism may include a discard policy that is enabled for one or more of the queues and that is based on the loading of the capacity of one of the other queues.

Claims

1. A queuing congestion mechanism to provide congestion management at an egress port of a packet switch, the queuing congestion mechanism comprising:

a first queue having an input, an output, and a capacity, the first queue operable to receive packets of information of a first type at its input that are destined to be communicated to the egress port through its output;

a second queue having an input, an output, and a capacity, the second queue operable to receive packets of information of a second type at its input that are destined to be communicated to the egress port through its output;

a third queue having an input, an output, and a capacity, the third queue operable to receive packets of information of a third type at its input that are destined to be communicated to the egress port through its output;

a scheduler operable to receive the packets of information from the output of the first queue, the output of the second queue, and the output of the third queue, and to communicate the packets of information to the egress port of the packet switch based on a schedule; and

a queue shaper operable to set an adjustable rate in which the packets of information of the third queue are communicated to the scheduler, wherein the adjustable rate is controlled by a loading of the capacity of the second queue.

2. The queuing congestion mechanism of claim 1, wherein a discard policy is enabled for the third queue based on the loading of the capacity of the second queue.

3. The queuing congestion mechanism of claim 2, wherein a discard policy is enabled for the second queue based on the loading of the capacity of the second queue.

4. The queuing congestion mechanism of claim 3, wherein a discard policy is enabled for the first queue based on the loading of the capacity of the second queue.

5. The queuing congestion mechanism of claim 1, wherein the first queue is assigned a first priority, the second queue is assigned a second priority that is a lower priority than the first priority, and the third queue is assigned a third priority that is a lower priority than both the second priority and the third priority.

6. The queuing congestion mechanism of claim 5, wherein the scheduler is a strict scheduler and the schedule is determined by priorities of the queues.

7. The queuing congestion mechanism of claim 5, wherein the scheduler is a weighted fair queuing scheduler and the schedule is determined by weighting the priorities of the queues.

8. The queuing congestion mechanism of claim 1, wherein each queue corresponds to a service category queue.

9. The queuing congestion mechanism of claim 1, wherein the packet switch is an ATM switch of an ATM network.

10. The queuing congestion mechanism of claim 1, wherein the packet switch is an IP switch of an IP network.

11. The queuing congestion mechanism of claim 1, wherein the packet switch is a frame relay switch of a frame relay network.

12. The queuing congestion mechanism of claim 1, wherein the packet switch is an MPLS switch of an MPLS network.

13. The queuing congestion mechanism of claim 1, wherein the packet switch is an Ethernet switch of an Ethernet network.

14. A packet switch with at least one queuing congestion mechanism for use in a packet network that includes a plurality of packet switches in communication through a plurality of telecommunications links, the packet switch comprising:

a plurality of ingress ports, each of the plurality of ingress ports operable to receive packets of information from one of the plurality of telecommunications links of the packet network;

a plurality of egress ports, each of the plurality of egress ports operable to communicate packets of information to one of the plurality of telecommunications links of the packet network;

a switch matrix operable to receive packets of information from the plurality of ingress ports, to perform packet switching on the packets of information, and to communicate the packets of information to a designated one of the plurality of egress ports; and

at least one queuing congestion mechanism operable to provide congestion management at one of the plurality of egress ports, the congestion mechanism including;

a first queue having an input, an output, and a capacity, the first queue operable to receive packets of information of a first type at its input that are destined to be communicated to the egress port through its output,

a second queue having an input, an output, and a capacity, the second queue operable to receive packets of information of a second type at its input that are destined to be communicated to the egress port through its output,

a third queue having an input, an output, and a capacity, the third queue operable to receive packets of information of a third type at its input that are destined to be communicated to the egress port through its output,

a scheduler operable to receive the packets of information from the output of the first queue, the output of the second queue, and the output of the third queue, and to communicate the packets of information to the egress port of the packet switch based on a schedule, and

a queue shaper operable to set an adjustable rate in which the packets of information of the third queue are communicated to the scheduler, wherein the adjustable rate is controlled by a loading of the capacity of the second queue.

15. The packet switch of claim 14, wherein a discard policy is enabled for the third queue based on the loading of the capacity of the second queue.

16. The packet switch of claim 14, wherein the packet network is an ATM network and the packet switch is an ATM switch.

17. The packet switch of claim 14, wherein the packet network is an MPLS network and the packet switch is an MPLS switch.

18. A method for performing queuing closed loop congestion management in a packet switch of a packet network, the method comprising:

monitoring the loading of the capacity of a first queue, a second queue, and a third queue to hold packets of information communicated through the packet network, each queue associated with an egress port of the packet switch and associated with different levels of service;

setting an adjustable data rate to communicate the packets of information of the third queue to a scheduler, wherein the adjustable data rate is controlled by the loading of the capacity of the second queue;

scheduling the communication of the packets of information from the first queue, the second queue, and the third queue to the egress port of the packet switch based on a schedule; and

enabling a discard policy for the third queue based on the loading of the capacity of the second queue.