Random early detect and differential packet aging flow control in switch queues

Abstract

Flow control is provided for a packet switch. An incoming packet is classified according to its priority based on predefined rules to produce a weight value based on the priority of the packet. A lifetime value associated with the packet is produced based on the weight value and the queue occupancy in a queue to which the packet is assigned. The packet is discarded if its associated lifetime value is less than or equal to a threshold value. Otherwise the packet and associated lifetime value are sent to the queue. The lifetime value is periodically changed and compared to a threshold value. The packet is removed from the queue when its lifetime value reaches the threshold value.

Description

FIELD OF THE INVENTION [0001] The present invention relates to flow control in devices utilizing queuing systems for packets. BACKGROUND OF THE INVENTION [0002] Devices using queuing systems for packets, for example gateways, switches and routers, are often used in networks supporting IP or TCPIP, such as Ethernet. A problem is, however, that packets get stuck in that queues when there is congestion in the network, or when a link is down or not ready. Under this stuck condition two things happen. [0003] (1) Packets are stored in buffers and referenced through link lists. Complex conditions arise when packets are destined for multiple ports, and the packets can exit from some of the ports but not from others. Furthermore, new packets enter from other ports. The result can be that the packets can get stuck in the buffers indefinitely. [0004] (2) Buffer space can be taken up by packets that are of lower priority, and higher priority packets get dropped. [0005] One prior art solution is...

AI Technical Summary

Benefits of technology

[0008] The present invention helps solve the problems of stagnant packets within queues, dropped high-priority packets and network congestion, using a random early detect and differential packet aging flow control method. A differential random early detect mechanism is used to prevent congestion in the Internet traffic. An aging mechanism solves the problem of packets being locked in the queue of a switching device for a certain time because it cannot exit the queue.

Problems solved by technology

A problem is, however, that packets get stuck in that queues when there is congestion in the network, or when a link is down or not ready.

Complex conditions arise when packets are destined for multiple ports, and the packets can exit from some of the ports but not from others.

The result can be that the packets can get stuck in the buffers indefinitely.

The disadvantage of this solution is that during the time when the packets are locked in the switching device, they take up valuable space resources.

The disadvantage of this solution is that it does not differentiate between low and high priority packets.

It also does not differentiate between time critical packets (e.g. for real time applications such as voice-over-IP, video-over-IP or other types of time critical packets).

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