Method and arrangement in a communication system
A method for performing admission control in order to offer assurances on forwarding quality in networks comprising setting a threshold for each link where the threshold defines a maximum sum of forwarding resources requested by applications for their application data flows, ADFs, on the link. The level of the threshold is chosen by utilising knowledge about multiplexing properties of the ADFs on each link and by utilising knowledge about the forwarding resources of the links.
1. A method for performing admission control in order to offer assurances on forwarding quality in networks comprising the steps of:
setting a resources requested threshold for each link where said resources requested threshold defines a maximum sum of forwarding resources requested by applications for their application data flows, ADFs, on the link;
calculating a measurement level threshold, the measurement level threshold being a rate lower than the resources requested threshold;
determining whether a reservation level exceeds the measurement level threshold;
upon determining that the reservation level exceeds the measurement level threshold, repeatedly measuring, during usage, multiplexing properties of aggregated ADFs on each link, each measuring being performed over a period of time;
dynamically adapting said resources requested threshold by utilizing the measured multiplexing properties of the ADFs on each link and by utilizing knowledge about the forwarding resources of the links;
recalculating the measurement level threshold based on the dynamically adapted resources requested threshold; and
preventing an overload before it occurs by controlling admission to each link based on the dynamically adapted resources requested threshold.
2. The method according to claim 1 , further comprising setting an initial threshold for each link.
3. The method according to claim 2 , characterized by choosing the initial threshold by estimating multiplexing properties of different ADFs off-line, said estimation being based on results from preparatory tests of recorded samples of ADFs, which are expected on a link and use this estimation when choosing the level of said threshold.
4. The method according to claim 2 , characterized by performing the measurements at least two different rates.
5. The method according to claim 4 , characterized by measuring at a first rate, which is equal to or lower than an amount of allocated resources on the link and measuring at a second rate, which is lower than the first rate.
6. The method according to claim 5 , wherein the second rate is dependent on reserved resources on the link and the resources requested threshold.
7. The method according to claim 5 , characterized by
increasing the resources requested threshold when both the measurement at the first and second rates indicate lower loss-rates than what is assured;
decreasing the resources requested threshold when both the measurement at the first and second rates indicate higher loss-rates than what is assured; and
maintaining the resources requested threshold when the measurement at the second rate indicates a higher loss-rate than assured and the measurement at the first rate indicates a lower loss-rate than assured.
8. The method according to claim 5 , characterized by introducing a measurement threshold, which defines a level of forwarding capacity reservations on the link above which the measurements are initiated.
9. The method according to claim 8 , characterized by increasing the measurement threshold in steps but not over a predefined maximum level which is lower than a level of allocated resources of the link when the measurement at the second rate indicates a higher loss-rate than assured and the measurement at the first rate indicates a lower loss-rate than assured.
10. The method according to claim 5 , characterized by measuring at a third rate, which is higher than the first rate but equal to or lower than the allocated resources of the link when the measurement at the first rate indicates a higher loss-rate than assured, the loss-rate measured at the third rate being indicative of if it is necessary to pre-empt ADFs from the link or if it is enough to prevent new ADFs from entering the link.
11. A node in a network comprising a memory and a processor performing admission control in order to offer assurances on forwarding quality in networks and software for setting a threshold for each link, said threshold defining a maximum sum of forwarding resources requested by applications for their application data flows, ADFs, on the link, characterized in that said node further comprises software for performing the method in claim 1 .
12. A node in a network according to claim 11 , characterized in that it comprises or is connectable to a measuring means adapted to perform measurements on the links.
13. A computer program product directly loadable into the internal memory of a processing means within a computer placed in a node, the computer program product being embodied in a non-transitory medium readable by the computer, wherein the medium readable by the computer comprises a software code means for performing the steps of claim 1 .
14. A computer program product embodied in a computer-readable non-transitory medium, the computer-readable non-transitory medium comprising a readable program for causing a processing means to control an execution of the steps of claim 1 .
15. A computer program product for providing admission control, the computer program product having a non-transitory computer-readable medium with a computer program embodied thereon, the computer program comprising:
computer program code for setting a resources requested threshold for each link where said resources requested threshold defines a maximum sum of forwarding resources requested by applications for their application data flows, ADFs, on the link;
computer program code for calculating a measurement level threshold, the measurement level threshold being a rate lower than the resources requested threshold;
determining whether a reservation level exceeds the measurement level threshold;
computer program code for, upon determining that the reservation level exceeds the measurement level threshold, repeatedly measuring, during usage, multiplexing properties of aggregated ADFs on each link, each measuring being performed over a period of time;
computer program code for dynamically adapting a level of said resources requested threshold by utilizing the measured multiplexing properties of the ADFs on each link and by utilizing knowledge about the forwarding resources of the links;
computer program code for recalculating the measurement level threshold based on the dynamically adapted resources requested threshold; and
computer program code for preventing an overload before it occurs by controlling admission to each link based on the dynamically adapted resources requested threshold.
16. The computer program product of claim 15 , further comprising computer program code for setting an initial threshold for each link.
17. The computer program product of claim 16 , further comprising computer program code for choosing the initial threshold by estimating multiplexing properties of different ADFs off-line, said estimation being based on results from preparatory tests of recorded samples of ADFs, which are expected on a link.
18. The computer program product of claim 16 , further comprising computer program code performing the measurements at least two different rates.
19. The computer program product of claim 18 , further comprising computer program code for measuring at a first rate, which is equal to or lower than an amount of allocated resources on the link and for measuring at a second rate, which is lower than the first rate.
20. The computer program product of claim 19 , wherein the second rate is dependent on reserved resources on the link and the threshold.
21. The computer program product of claim 19 , further comprising,
computer program code for increasing the resources requested threshold when both the measurement at the first and second rates indicate lower loss-rates than what is assured;
computer program code for decreasing the resources requested threshold when both the measurement at the first and second rates indicate higher loss-rates than what is assured; and
computer program code for maintaining the resources requested threshold when the measurement at the second rate indicates a higher loss-rate than assured and the measurement at the first rate indicates a lower loss-rate than assured.
22. The computer program product of claim 16 , further comprising computer program code for introducing a measurement threshold, which defines a level of forwarding capacity reservations on the link above which the measurements are initiated.
23. The computer program product of claim 19 , further comprising computer program code for increasing the resources requested threshold in steps but not over a predefined maximum level which is lower than a level of allocated resources of the link when the measurement at the second rate indicates a higher loss-rate than assured and the measurement at the first rate indicates a lower loss-rate than assured.
24. The computer program product of claim 19 , further comprising computer program code for measuring at a third rate, which is higher than the first rate but equal to or lower than the allocated resources of the link when the measurement at the first rate indicates a higher loss-rate than assured, the loss-rate measured at the third rate being indicative of if it is necessary to pre-empt ADFs from the link or if it is enough to prevent new ADFs from entering the link.