Network routing protocol power saving method for network elements

1. A method comprising:

determining a network topology in a network comprising a plurality of network elements comprising nodes linked in communication via a plurality of links;

based on utilization of the links, identifying links among the plurality of links that are candidates for power management and links that are not candidates for power management;

effecting operation of links that are not candidates for power management at full power;

detecting, from among the links that are candidates for power management, a condition under which a power state of a link may be changed, the condition comprising a link power-state change condition and being determined as a function of utilization of the link; and

effecting a change in the power-state for the link by effecting a change in the power state of first and second ports of respective first and second network elements linked in communication via the link.

2. The method of claim 1 , wherein effecting a change in the power state for a link comprises taking the link offline by effecting powering off network interfaces corresponding to the first and second ports.

3. The method of claim 1 , wherein effecting a change in the power state for a link comprises effecting a reduction of a power state to an idle state for each of the first and second ports.

4. The method of claim 1 , further comprising identifying links among the plurality of links that are candidates for power management as a function of longer term link utilization, wherein the longer term link utilization is measured over an extended time period.

5. The method of claim 1 , further comprising detecting a condition under which a power state of a link is to be changed based on a utilization level of the link, where the utilization level of links is determined using relatively short time periods.

6. The method of claim 1 , further comprising employing a network element to detect a link power-state change condition.

7. The method of claim 1 , further comprising employing a network management entity to detect a link power-state change condition.

8. The method of claim 1 , wherein effecting a power state change for the link comprises:

sending a power management packet from the first network element to the second network element indicating a change in link power state to be effected at the second network element by changing the power state of the second port;

receiving a power management ACK packet from the second network element at the first network element; and

changing the power state of the first port in accordance with the link power state identified in the power management packet.

9. The method of claim 1 , further comprising:

determining an updated network topology in the network in response to at least one of a change in the power state of one or more links and a change in network traffic; and

updating a list of links that are candidates for power management in view of the updated network topology.

10. The method of claim 1 , wherein determining the network link topology and identifying links that are candidates for power management comprises:

identifying nodes and links connecting the nodes;

determining a utilization of the links;

determining a most utilized link spanning tree for the network link topology; and

identifying links that are not links in the most utilized link spanning tree as candidates for power management.

11. The method of claim 10 , further comprising employing a link-state protocol using the utilization of the links to determine link paths in the most utilized link spanning tree.

12. The method of claim 10 , further comprising employing a distance vector routing protocol using the utilization of the links to determine link paths in the most utilized link spanning tree.

13. The method of claim 10 , further comprising

employing a Spanning Tree protocol using link utilization as a routing criteria to determine ports in the network elements comprising root ports and designated ports; and

identifying links that are not coupled to a root port or a designated port as a candidate for power management.

14. The method of claim 1 , further comprising:

detecting a network condition under which a link in a reduced power state is to be brought back to a higher power state; and

effecting a power state change for the link by effecting a change in the power state of network element ports coupled to the ends of the link from a reduced power state to a higher power state.

15. The method of claim 14 , wherein the network condition under which a link in a reduced power state is to be brought back to a higher power state is detected as a function of one or more link and/or network performance factors.

16. The method of claim 15 , wherein the network condition under which a link in a reduced power state is to be brought back to a higher power state is detected by a network element.

17. The method of claim 15 , wherein the network condition under which a link in a reduced power state is to be brought back to a higher power state is detected by a network management entity.

18. The method of claim 1 , further comprising:

maintaining a list of links that have been put into a reduced power state;

detecting a link power up condition, under which a link in a reduced power state is to be powered up to a higher power state; and

selecting a link to power up from the list of links that have been put into a reduced power state.

19. The method of claim 18 , further comprising:

maintaining an ordered list of links put into a reduced power state; and

selecting the last link added to the ordered list as the first link to power back up.

20. An apparatus comprising:

a processor

memory, operatively coupled to the processor;

a network interface;

a storage device, having instructions stored therein configured to be executed by the processor to cause the apparatus to perform operations including,

coupling the network interface in communication with a network comprising a plurality of network elements comprising nodes linked in communication via a plurality of links;

determining a network topology in the network;

based on utilization of the links, identifying links among the plurality of links that are candidates for power management and links that are not candidates for power management;

effecting operation of links that are not candidates for power management at full power;

detecting, from among the links that are candidates for power management, a condition under which a power state of a link may be changed, the condition comprising a link power-state change condition and being determined as a function of utilization of the link; and

effecting a change in the power-state for the link by effecting a change in the power state of first and second ports of respective first and second network elements linked in communication via the link.

21. The apparatus of claim 20 , wherein effecting a change in the power state for a link comprises taking the link offline by effecting powering off network interfaces corresponding to the first and second ports.

22. The apparatus of claim 20 , wherein effecting a change in the power state for a link comprises effecting a reduction of a power state to an idle state for each of the first and second ports.

23. The apparatus of claim 20 , wherein execution of the instructions cause the apparatus to perform further operation comprising identifying links among the plurality of links that are candidates for power management as a function of longer term link utilization, wherein the longer term link utilization is measured over an extended time period.

24. The apparatus of claim 20 , wherein execution of the instructions cause the apparatus to perform further operation comprising detecting a condition under which a power state of a link is to be changed based on a utilization level of the link, where the utilization level of links is determined using relatively short time periods.

25. The apparatus of claim 20 , wherein determining the network link topology and identifying links that are candidates for power management comprises:

identifying nodes and links connecting the nodes;

determining a utilization of the links;

determining a most utilized link spanning tree for the network link topology; and

identifying links that are not links in the most utilized link spanning tree as candidates for power management.

26. A tangible non-transitory machine readable medium comprising a plurality of instructions that in response to being executed by an apparatus to cause the apparatus perform operations comprising:

coupling a network interface of the apparatus in communication with a network comprising a plurality of network elements comprising nodes linked in communication via a plurality of links;

determining a network topology in the network;

based on utilization of the links, identifying links among the plurality of links that are candidates for power management and links that are not candidates for power management;

effecting operation of links that are not candidates for power management at full power;

detecting, from among the links that are candidates for power management, a condition under which a power state of a link may be changed, the condition comprising a link power-state change condition and being determined as a function of utilization of the link; and

effecting a change in the power-state for the link by effecting a change in the power state of first and second ports of respective first and second network elements linked in communication via the link.

27. A tangible non-transitory machine readable medium of claim 26 , wherein effecting a change in the power state for a link comprises taking the link offline by effecting powering off network interfaces corresponding to the first and second ports.

28. A tangible non-transitory machine readable medium of claim 26 , wherein effecting a change in the power state for a link comprises effecting a reduction of a power state to an idle state for each of the first and second ports.

29. A tangible non-transitory machine readable medium of claim 26 , wherein execution of the instructions cause the apparatus to perform further operation comprising identifying links among the plurality of links that are candidates for power management as a function of longer term link utilization, wherein the longer term link utilization is measured over an extended time period.

30. A tangible non-transitory machine readable medium of claim 26 , wherein determining the network link topology and identifying links that are candidates for power management comprises: identifying nodes and links connecting the nodes; determining a utilization of the links; determining a most utilized link spanning tree for the network link topology; and

identifying links that are not links in the most utilized link spanning tree as candidates for power management.