Methods and apparatus for providing congestion information

A method for using a first and a second register in combination to provide information relating to congestion at a network element caused by data units intended to be forwarded across a telecommunications network by the network element, the first register being operable to have stored therein a first metric which may be updated to levels between two predetermined thresholds of the first register, and the second register being operable to have stored therein a second metric which may be updated to levels between two predetermined thresholds of the second register, the method comprising:

• receiving load data relating to data units intended to be forwarded by the network element;
• obtaining data indicative of a configurable rate, said configurable rate relating to a rate at which data units are to be forwarded by the network element;
• performing a load-dependent operation of updating the metric in at least one of said first and second registers in dependence on said load data, said load-dependent operation involving updating the first register in the event that such an update is insufficient to cause the metric stored in the first register to cross a first predetermined threshold thereof, and in the event that such an update would be sufficient to cause the metric stored in the first register to cross said first predetermined threshold thereof, updating the second register in the event that such an update is insufficient to cause the metric stored in the second register to cross a first predetermined threshold thereof;
• performing a rate-dependent operation of updating the metric in at least one of said first and second registers in dependence on the configurable rate, said rate-dependent operation involving updating the second register in the event that such an update is insufficient to cause the metric stored in the second register to cross a second predetermined threshold thereof, and in the event that such an update would be sufficient to cause the metric stored in the second register to cross said second predetermined threshold thereof, updating the first register in the event that such an update would not cause the metric stored in the first register to cross a second predetermined threshold thereof;
• and
• providing an indication of congestion in the event that an update to either of said first and second registers resulting from performing said load-dependent operation would be sufficient to cause the metric stored in that register to cross its respective first threshold.

A system for providing information relating to congestion at a network element caused by data units intended to be forwarded across a telecommunications network by the network element, the system comprising:

• a load-data receiver configured to receive load data relating to data units intended to be forwarded by the network element;
• a first register configured to have stored therein a first metric which may be updated to levels between two predetermined thresholds of the first register;
• a second register configured to have stored therein a second metric which may be updated to levels between two predetermined thresholds of the second register;
• and
• a computer processing system, comprising a computer processor, configured to:
• obtain data indicative of a configurable rate, said configurable rate relating to a rate at which data units are to be forwarded by the network element;
• perform a first update to update the metric in at least one of said first and second registers in dependence on said load data, said first update updating the first register in the event that such an update is insufficient to cause the metric stored in the first register to cross a first predetermined threshold thereof, and in the event that such an update would be sufficient to cause the metric stored in the first register to cross said first predetermined threshold thereof, to update the second register in the event that such an update is insufficient to cause the metric stored in the second register to cross a first predetermined threshold thereof;
• perform a second update to update to update the metric in at least one of said first and second registers in dependence on the configurable rate, said second update updating the second register in the event that such an update is insufficient to cause the metric stored in the second register to cross a second predetermined threshold thereof, and in the event that such an update would be sufficient to cause the metric stored in the second register to cross said second predetermined threshold thereof, to update the first register in the event that such an update would not cause the metric stored in the first register to cross a second predetermined threshold thereof;
• and
• provide a congestion indication responsive to said first update and to provide an indication of a primary level of congestion in the event that an update by said first update to either of said first and second registers would be sufficient to cause the metric stored in that register to cross its first respective threshold.