Signalling congestion

摘要

Methods and apparatus are disclosed for signalling congestion being caused by data items such as packets, received at a network element such as a router, in a communications network such as the Internet, or being caused by items otherwise requiring service or capacity from a shared resource. Preferred embodiments of the method involve identifying whether or not received data items received at a network element are capable of carrying congestion indications such as ECN marks, and for those that are capable, assigning congestion indications to the data items in dependence on a queue length characterization based on a substantially current, instantaneous measurement of the length of the queue, whereas for those that are not capable, a sanction such as dropping may be applied in dependence on a different queue length characterization based on a weighted moving average of current, recent, and less recent measurements of the length of the queue.

主权项

1. A method of signalling congestion being caused by data items received at a network element in a communications network, the network element having a queue having a length, the method comprising steps of:
identifying, in respect of each of a plurality of received data items, whether or not said data item is capable of carrying a congestion indication; determining a first queue length characterisation, said first queue length characterisation being determined according to a first function such as to depend on measurements inferring the length of the queue at a plurality of different times; determining a second queue length characterisation, said second queue length characterisation being determined according to a second function such as to depend on a current or recent measurement inferring the length of the queue, the most recent queue length being more strongly weighted in said second function than it is in said first function; applying a sanction in respect of data items identified as not being capable of carrying congestion indications in dependence on said first queue length characterisation; and assigning congestion indications to data items identified as being capable of carrying congestion indications in dependence on said second queue length characterisation.