Adaptive Buffering in a Distributed System with Latency/Adaptive Tail Drop

Patent metadata

Field	Value
Publication number	US-2023013331-A1
Application number	US-202217953031-A
Country	US
Kind code	A1
Filing date	Sep 26, 2022
Priority date	Oct 23, 2020
Publication date	Jan 19, 2023
Grant date	—

Abstract

A network device includes a switching system for directing packets between ingress ports and egress ports of the network device. The network device also includes a switching system manager that makes an identification of a state change of a virtual output queue of the switching system; and performs an action set, based on the state change, to modify a latency of the virtual output queue to meet a predetermined latency in response to the identification.

First claim

What is claimed is:

1 . A network device for directing packets between ingress ports and egress ports of the network device, comprising:
a switching system manager programmed to:
make an identification of a latency state change of a virtual output queue of the switching system; and
perform an action set, in response to the identification of the latency state change, to modify a drop rate at which packets received by a packet processor are dropped such that a latency of packets in the virtual output queue is bound within a predetermined range.

2 . The network device of claim 1 , wherein the action set comprises:
modifying a processing rate at which packets are dequeued from the virtual output queue and processed, the processing rate based on the state change of the virtual output queue.

3 . The network device of claim 1 , wherein the action set comprises:
modifying an amount of storage allocated to the virtual output queue and processed, the amount of storage based on the state change of the virtual output queue.

4 . The network device of claim 1 , wherein the action set comprises:
modifying a percentage drop rate implemented by the packet processor, wherein the packet processor drops received packets at the percentage drop rate without attempting to enqueue the dropped packets in the virtual output queue.

5 . The network device of claim 1 , wherein:
in response to the state change comprising the latency of packets in the virtual output queue being greater than a first predetermined latency, the action set increases the drop rate; and in response to the state change comprising the latency of packets in the virtual output queue being less than a second predetermined latency, the action set increases the drop rate.

6 . The network device of claim 1 , wherein the switching system manager is further programmed to:
prior to identifying the state change:
identify a change in an ingress rate of the virtual output queue;
in response to identifying the change in the ingress rate of the virtual output queue:
perform a second action set, based on the change in the ingress rate of the virtual output queue, to modify the latency of the virtual output queue to meet the predetermined latency.

7 . The network device of claim 6 , wherein performing the second action set comprises:
modifying a processing rate associated with the virtual output queue, wherein the processing rate is modified based on an egress rate of an egress port of the egress ports that is associated with the virtual output queue, and the change in the ingress rate.

8 . A method for directing packets between ingress ports and egress ports of a network device, comprising:
making an identification of a latency state change of a virtual output queue of a switching system for directing packets between the ingress ports and the egress ports of the network device; and perform an action set, in response to the identification of the state change, to modify a drop rate at which packets received by a packet processor are dropped such that a latency of packets in the virtual output queue is bound within a predetermined range.

9 . The method of claim 8 , wherein the action set comprises:
modifying a processing rate at which packets are dequeued from the virtual output queue and processed, the processing rate based on the state change of the virtual output queue.

10 . The method of claim 8 , wherein the action set comprises:
modifying an amount of storage allocated to the virtual output queue and processed, the amount of storage based on the state change of the virtual output queue.

11 . The method of claim 8 , wherein the action set comprises:
modifying a percentage drop rate implemented by the packet processor, wherein the packet processor drops received packets at the percentage drop rate without attempting to enqueue the dropped packets in the virtual output queue.

12 . The method of claim 8 , further comprising:
in response to the state change comprising the latency of packets in the virtual output queue being greater than a first predetermined latency, the action set increases the drop rate; and in response to the state change comprising the latency of packets in the virtual output queue being less than a second predetermined latency, the action set increases the drop rate.

13 . The method of claim 8 , further comprising:
prior to identifying the state change:
identify a change in an ingress rate of the virtual output queue;
in response to identifying the change in the ingress rate of the virtual output queue:
perform a second action set, based on the change in the ingress rate of the virtual output queue, to modify the latency of the virtual output queue to meet the predetermined latency.

14 . The method of claim 13 , wherein performing the second action set comprises:
modifying a processing rate associated with the virtual output queue, wherein the processing rate is modified based on an egress rate of an egress port of the egress ports that is associated with the virtual output queue, and the change in the ingress rate.

15 . A non-transitory computer readable medium comprising computer readable program code, which when executed by a computer processor enables the computer processor to perform a method, the method comprising:
making an identification of a state change of a virtual output queue of a switching system for directing packets between ingress ports and egress ports of a network device; and perform an action set, in response to the identification of the state change, to oscillate a latency of the virtual output queue between a first predetermined latency and a second predetermined latency lower than the first predetermined latency such that the latency of the virtual output queue is bound within a predetermined range based on a quality of forwarding services to be provided by the network device.

16 . The non-transitory computer readable medium of claim 15 , wherein the action set comprises:
modifying a processing rate at which packets are dequeued from the virtual output queue and processed, the processing rate based on the state change of the virtual output queue.

17 . The non-transitory computer readable medium of claim 15 , wherein the action set comprises:
modifying an amount of storage allocated to the virtual output queue and processed, the amount of storage based on the state change of the virtual output queue.

18 . The non-transitory computer readable medium of claim 15 , wherein the action set comprises:
modifying a percentage drop rate implemented by the packet processor, wherein the packet processor drops received packets at the percentage drop rate without attempting to enqueue the dropped packets in the virtual output queue.

19 . The non-transitory computer readable medium of claim 15 , the method further comprising:
in response to the state change comprising the latency of packets in the virtual output queue being greater than a first predetermined latency, the action set increases the drop rate; and in response to the state change comprising the latency of packets in the virtual output queue being less than a second predetermined latency, the action set increases the drop rate.

20 . The non-transitory computer readable medium of claim 15 , the method further comprising:
prior to identifying the state change:
identify a change in an ingress rate of the virtual output queue;
in response to identifying the change in the ingress rate of the virtual ou

Assignees

• Arista Networks Inc

Inventors

• Labonte Francois

Classifications

• H04L47/56 Primary

  implementing delay-aware scheduling · CPC title

• H04L47/6215 Primary

  Individual queue per QOS, rate or priority · CPC title

• H04L47/326

  with random discard, e.g. random early discard [RED] · CPC title

• H04L47/6255

  queue load conditions, e.g. longest queue first · CPC title

• H04L47/283

  in response to processing delays, e.g. caused by jitter or round trip time [RTT] · CPC title