Adaptive queue-management

1. A method comprising, by one or more computing systems:

storing in a quality-of-service (QoS)-enabled communication system a data structure that has a multi-level hierarchy comprising:

a physical level comprising one or more physical-level nodes, each of the physical-level nodes corresponding to a physical interface for transmitting a bandwidth-limited traffic (BLT) stream of packets;

a logical level comprising one or more logical-level nodes, each of the logical-level nodes comprising a bandwidth-limitation parameter; and

a class level comprising one or more class-level nodes, each of the class-level nodes corresponding to a service provided by the QoS-enabled communication system;

receiving a first request for M number of services provided by the QoS-enabled communication system;

in response to the first request, modifying an allocation of the logical-level nodes by mapping M class-level nodes to a first one of the logical-level nodes according to a first mapping mode of the data structure;

receiving a second request for P services provided by the QoS-enabled communication system, P being greater than M; and

in response to the second request, modifying an allocation of the logical-level nodes by mapping P class-level nodes to a second one of the logical-level nodes according to a second mapping mode of the data structure.

2. The method of claim 1 , further comprising:

transferring the bandwidth limitation parameter of the first one of the logical-level nodes to the second one of the logical-level nodes, the transfer being in response to the second request; and

resetting the first one of the logical-level nodes.

3. The method of claim 2 , further comprising updating a list of logical-level nodes based at least in part on the automatically resetting of the second one of the logical-level nodes, each logical-level node included in the list of logical-level nodes having no corresponding class-level node mapped to it.

4. The method of claim 1 , further comprising:

transferring the bandwidth limitation parameter of the second one of the logical-level nodes to the first one of the logical-level nodes, the transfer being in response to the first request; and

resetting the second one of the logical-level nodes.

5. The method of claim 1 , further comprising partitioning the data structure into at least first and second partitions, the first partition storing a first plurality of mappings according the first mapping mode, the second partition storing a second plurality of mappings according to the second mapping mode.

6. The method of claim 1 , further comprising:

resetting a logical-level node;

determining the location of the reset logical-level node relative to the end of a range of memory of the data structure; and

in response to the determination, executing one of the following steps:

updating a variable identifying a last used logical-level node; and

adding the reset logical-level node to a list of logical-level nodes, each logical-level node included in the list of logical-level nodes having no corresponding class-level node mapped to it.

7. The method of claim 1 , wherein:

M and P are both factors of 2; and

the first one of the logical-level nodes comprises the second one of the logical-level nodes.

8. The method of claim 1 , wherein:

the first mapping mode ratio is a 4:1 ratio of the class-level nodes to the logical-level nodes; and

the second mapping mode ratio is a 8:1 mapping mode ratio of the class-level nodes to the logical-level nodes.

9. One or more computer-readable non-transitory storage media embodying software this is operable when executed by one or more computer systems to:

store in a quality-of-service (QoS)-enabled communication system a data structure that has a multi-level hierarchy comprising:

a physical level comprising one or more physical-level nodes, each of the physical-level nodes corresponding to a physical interface for transmitting a bandwidth-limited traffic (BLT) stream of packets;

a logical level comprising one or more logical-level nodes, each of the logical-level nodes comprising a bandwidth-limitation parameter; and

a class level comprising one or more class-level nodes, each of the class-level nodes corresponding to a service provided by the QoS-enabled communication system;

receive a first request for M number of services provided by the QoS-enabled communication system;

in response to the first request, modify an allocation of the logical-level nodes by mapping M class-level nodes to a first one of the logical-level nodes according to a first mapping mode of the data structure;

receive a second request for P services provided by the QoS-enabled communication system, P being greater than M; and

in response to the second request, modify an allocation of the logical-level nodes by mapping P class-level nodes to a second one of the logical-level nodes according to a second mapping mode of the data structure.

10. The media of claim 9 , wherein the software is further operable when executed to:

transfer the bandwidth limitation parameter of the first one of the logical-level nodes to the second one of the logical-level nodes, the transfer being in response to the second request; and

reset the first one of the logical-level nodes.

11. The media of claim 10 , wherein the software is further operable when executed to update a list of logical-level nodes based at least in part on the automatically resetting of the second one of the logical-level nodes, each logical-level node included in the list of logical-level nodes having no corresponding class-level node mapped to it.

12. The media of claim 9 , wherein the software is further operable when executed to:

transfer the bandwidth limitation parameter of the second one of the logical-level nodes to the first one of the logical-level nodes, the transfer being in response to the first request; and

reset the second one of the logical-level nodes.

13. The media of claim 9 , wherein the software is further operable when executed to partition the data structure into at least first and second partitions, the first partition storing a first plurality of mappings according the first mapping mode, the second partition storing a second plurality of mappings according to the second mapping mode.

14. The media of claim 9 , wherein the software is further operable when executed to:

reset a logical-level node;

determine the location of the reset logical-level node relative to the end of a range of memory of the data structure; and

in response to the determination, execute one of the following steps:

update a variable identifying a last used logical-level node; and

add the reset logical-level node to a list of logical-level nodes, each logical-level node included in the list of logical-level nodes having no corresponding class-level node mapped to it.

15. The media of claim 9 , wherein:

M and P are both factors of 2; and

the first one of the logical-level nodes comprises the second one of the logical-level nodes.

16. The media of claim 9 , wherein:

the first mapping mode ratio is a 4:1 ratio of the class-level nodes to the logical-level nodes; and

the second mapping mode ratio is a 8:1 mapping mode ratio of the class-level nodes to the logical-level nodes.

17. An apparatus comprising:

one or more communication interfaces;

one or more memory devices containing one or more instructions for execution by one or more processing devices; and

the processing devices, operable when executing the instructions to:

store in a quality-of-service (QoS)-enabled communication system a data structure that has a multi-level hierarchy comprising:

a physical level comprising one or more physical-level nodes, each of the physical-level nodes corresponding to a physical interface for transmitting a bandwidth-limited traffic (BLT) stream of packets;

a logical level comprising one or more logical-level nodes, each of the logical-level nodes comprising a bandwidth-limitation parameter; and

a class level comprising one or more class-level nodes, each of the class-level nodes corresponding to a service provided by the QoS-enabled communication system;

receive a first request for M number of services provided by the QoS-enabled communication system;

in response to the first request, modify an allocation of the logical-level nodes by mapping M class-level nodes to a first one of the logical-level nodes according to a first mapping mode of the data structure;

receive a second request for P services provided by the QoS-enabled communication system, P being greater than M; and

in response to the second request, modify an allocation of the logical-level nodes by mapping P class-level nodes to a second one of the logical-level nodes according to a second mapping mode of the data structure.

18. The apparatus of claim 17 , wherein the processing devices are further operable when executing the instructions to:

transfer the bandwidth limitation parameter of the first one of the logical-level nodes to the second one of the logical-level nodes, the transfer being in response to the second request; and

reset the first one of the logical-level nodes.

19. The apparatus of claim 18 , wherein the processing devices are further operable when executing the instructions to update a list of logical-level nodes based at least in part on the automatically resetting of the second one of the logical-level nodes, each logical-level node included in the list of logical-level nodes having no corresponding class-level node mapped to it.

20. The apparatus of claim 17 , wherein the processing devices are further operable when executing the instructions to:

transfer the bandwidth limitation parameter of the second one of the logical-level nodes to the first one of the logical-level nodes, the transfer being in response to the first request; and

reset the second one of the logical-level nodes.