Method and system for processing downstream packets of an optical network

• US 20030086140A1
• Filed: 10/26/2001
• Published: 05/08/2003
• Est. Priority Date: 10/26/2000
• Status: Active Grant

• Current Assignee: ARRIS Solutions, Inc. (CommScope Holding Company, Inc.)
• Original Assignee: Wave7 Optics, Inc. (Enablence Technologies Incorporated)
• Inventors: Thomas, Stephen, Whittlesey, Paul, Quinn, Patrick, Vella, Emmanuel, Kenny, John, Tighe, Thomas, Farmer, James, Bourg, Kevin, Caltagirone, Joe
• Granted Patent: US 7,197,244 B2
• Time in Patent Office: Days
• US Class Current: 398/167.5
• CPC Class Codes: H04J 14/0226 Fixed carrier allocation, e.g. according to service
• CPC Class Codes: H04J 14/0232 for downstream transmission
• CPC Class Codes: H04J 14/0247 Sharing one wavelength for at least a group of ONUs
• CPC Class Codes: H04J 14/0252 Sharing one wavelength for at least a group of ONUs, e.g. for transmissions from-ONU-to-OLT or from-ONU-to-ONU
• CPC Class Codes: H04J 14/028 WDM bus architectures
• CPC Class Codes: H04J 14/0282 WDM tree architectures
• CPC Class Codes: H04J 14/0286 WDM hierarchical architectures
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/22 Adaptations for optical transmission
• CPC Class Codes: H04Q 11/0067 Provisions for optical access or distribution networks, e.g. Gigabit Ethernet Passive Optical Network (GE-PON), ATM-based Passive Optical Network (A-PON), PON-Ring
• CPC Class Codes: H04Q 11/0071 Provisions for the electrical-optical layer interface

Abstract

Unlike the conventional art which polices data at the entry points of a network, a transceiver node can police or monitor downstream bandwidths for quality of service at exit portions of an optical network. That is, the transceiver node can police downstream communication traffic near the outer edges of an optical network that are physically close to the subscribers of the optical network. In this way, a network provider can control the volume or content (or both) of downstream communications that are received by subscribers of the optical network. In addition to controlling the volume of communications that can be received by a subscriber, the transceiver node employs a plurality of priority assignment values for communication traffic. Some priority assignment values are part of a weighted random early discard algorithm that enables an output buffer to determine whether to drop data packets that are destined for a particular subscriber. In one exemplary embodiment, a weighted random early discard (WRED) priority value can be assigned according to the type of communication traffic supported by a packet.

Claims

1. An optical network system comprising:

an optical tap routing device;

a plurality of optical tap multiplexers for receiving downstream packets from the optical tap routing device, the optical tap routing device determining which downstream packets are sent to a respective multiplexer, each optical tap multiplexer comprising;

a plurality of classifiers for determining type of information contained in a downstream packet and for assigning a downstream packet to a particular policer, and

a plurality of policers for controlling bandwidth based upon a comparison between parameters assigned to each policer by a network provider and a downstream packet.

2. The optical network system of claim 1, wherein the parameters assigned to each policer comprise at least one of a peak rate, a burst size, and a sustained rate.

3. The optical network system of claim 1, wherein each policer controls bandwidth by assigning a weighted early random discard value to the packet.

4. The optical network system of claim 1, wherein each optical tap multiplexer further comprises a plurality of output buffers for storing at least one downstream packet received from a respective policer.

5. The optical network system of claim 1, further comprising a plurality of output buffers, each output buffer having an assigned priority value that is associated with an output buffer emptying sequence.

6. The optical network system of claim 3, wherein each output buffer evaluates a packet with a random early discard function that employs the weighted early random discard value.

7. The optical network system of claim 6, wherein the weighted early random discard value comprises a maximum drop probability value.

8. The optical network system of claim 7, further comprising a plurality of output buffers, each output buffer executes a random early discard function for a packet when an output buffer average volume is between a minimum and maximum threshold, the random early discard function employing the maximum drop probability value.

9. The optical network system of claim 1, wherein parameters assigned to a policer corresponds with a bandwidth subscription of a subscriber.

10. The optical network system of claim 9, wherein the bandwidth subscription measures a predetermined amount of a data to be received by a subscriber in bits per second.

11. The optical network system of claim 1, wherein one of the classifiers evaluates a differentiated service code point (DSCP) value of each downstream packet.

12. The optical network system of claim 1, wherein each classifier and each policer comprises one of a field programmable gate array (FPGA) and an application specific integrated circuit (ASIC).

13. A method for processing downstream packets of an optical network, comprising the steps of:

classifying a downstream packet by evaluating a header of the packet;

determining if the downstream packet matches at least one of rate and size parameters;

assigning one of two priority values to the downstream packet based upon the determination if the downstream packet matches one of rate and size parameters; and

determining whether to store a downstream packet in one of a plurality of buffers based upon a weighted random early discard function that employs one of the priority values.

14. The method of claim 13, wherein the step of determining if the downstream packet matches at least one of rate and size parameters further comprises the steps of:

determining whether a downstream packet exceeds a sustained rate; and

determining whether a downstream packet exceeds a burst size.

15. The method of claim 14, wherein the step of determining whether the downstream packet exceeds a sustained rate further comprises the step of executing a token bucket algorithm to measure the sustained rate.

16. The method of claim 13, further comprising the steps of:

determining if a downstream packet exceeds a peak rate; and

discarding a downstream packet if the downstream packet exceeds the peak rate.

17. The method of claim 16, wherein the step of determining whether the downstream packet exceeds a peak rate further comprises the step of executing a token bucket algorithm to measure the peak rate.

18. The method of claim 13, wherein the step of assigning one of two priority values to a downstream packet comprises the step of assigning a maximum drop probability value to the downstream packet.

19. The method of claim 18, wherein the step of assigning a maximum drop probability value further comprises the step of assigning the maximum drop probability value based upon a determination of whether a packet matches sustained rate.

20. The method of claim 19, wherein the communication traffic profile comprises one of a minimum bandwidth that a class or group of classes of subscribers is assured of receiving and a maximum bandwidth the subscriber can use over a time period.

21. The method of claim 13, further comprising the step of removing one or more packets from a plurality of output buffers in a predetermined order that corresponds with priority assignment given to each buffer relative to other buffers.

22. The method of claim 13, further comprising the step of executing the random early discard function that assesses parameters of the downstream packet when an output buffer average volume is between a minimum and maximum threshold, the random early discard function defining a drop probability value for the downstream packet.

23. The method of claim 13, wherein the step of classifying further comprises the step of evaluating a differentiated service code point (DSCP) value of the packet.

24. The method of claim 13, further comprising the steps of:

classifying the downstream packet with a classifier; and

mapping a downstream packet to policer that is associated with the classifier.

25. An network policer system comprising:

an optical network comprising;

a data service hub for generating downstream data packets;

a transceiver node coupled to the data service node at an exit path of the data service hub for receiving and processing the downstream data packets, the transceiver node further comprising;

a plurality of classifiers for determining type of information contained in a downstream packet, and

a plurality of policers for controlling bandwidth by one of discarding packets and assigning one of two priority values to a downstream packet;

an optical tap; and

a subscriber optical interface coupled to the optical tap.

26. The network policer system of claim 25, further comprising a plurality of buffers corresponding to the priority assignment and for executing a weighted random early discard function.

27. The network policer system of claim 25, wherein the transceiver node further comprises an optical tap routing device for passing downstream packets to the classifiers.

28. The network policer system of claim 25, wherein the priority values comprise weighted early random discard values.

29. The network policer system of claim 28, wherein weighted early random discard values comprise maximum drop probability values.

30. A method for policing downstream data packets exiting a network, comprising the steps of:

positioning a plurality of classifiers and policers at exit pathways of a network;

discarding downstream packets with the policers if they exceed a peak rate;

assigning one of at least two priority values to each downstream packet with the policers; and

controlling downstream data packet egress from the network at the exit pathways by evaluating the priority values.

31. The method of claim 30, wherein the step of assigning one of at least two priority values further comprises the steps of:

determining if a downstream packet matches a sustained rate; and

determining if a downstream packet matches a burst size.

32. The method of claim 30, wherein the step of controlling downstream data packet egress from the network comprises the step of determining whether to admit a downstream packet to one of a plurality of buffers based upon a weighted random early discard function that employs one of the priority values.

33. The method of claim 30, wherein the step of assigning one of at least two priority values comprises the step of assigning a maximum drop probability value to each downstream packet.