# US 2014/0192677 A1 · Network routing protocol power saving method for network elements > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192677 A1 - Document ID: US20140192677A1 - Status: Published application - Kind: A1 - Application number: 13/977,512 - Filed: 2012-06-29 - Published: 2014-07-10 - Earliest claimed: 2012-06-29 - Assignees: Intel Corporation - Inventors: Yen Hsiang Chew; Radia Perlman - Web page: https://patentgrep.com/patent/US20140192677A1 ## CPC - H04L 69/14: Multichannel or multilink protocols - G06F 1/3234: Power saving characterised by the action undertaken - H04L 12/28: characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] (wireless communication networks H04W {; arrangements for dividing the transmission path H04W40/00}) - H04L 41/0833: for reduction of network energy consumption - H04L 41/12: Discovery or management of network topologies - H04L 45/125: based on throughput or bandwidth - H04L 45/48: Routing tree calculation - Y02D 30/50: in wire-line communication networks, e.g. low power modes or reduced link rate - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE ## Abstract Methods and apparatus relating to network routing protocols to support power savings in network elements. A most utilized link path network topology for a computer network is discovered using a routing protocol such as a Spanning Tree, link-state, or distance vector routing protocol. In view of the most utilized link path network topology, links are identified as candidates for power management under which a power state of the link and associated network ports are managed to save power under applicable link conditions, such as low utilization. Link power-state change conditions are detected, and in response a corresponding change to the power state of a link is effected by changing the power-state of the network ports at the ends of the link. Power state changes include putting a link into a reduced power state, taking a link offline, and powering a link back up. ## Claims ### Claim at position 1 1-24. (canceled) ### Claim 25 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. ### Claim 26 (depends on 25) The method of claim 25, 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. ### Claim 27 (depends on 25) The method of claim 25, 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. ### Claim 28 (depends on 25) The method of claim 25, 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. ### Claim 29 (depends on 25) The method of claim 25, 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. ### Claim 30 (depends on 25) The method of claim 25, further comprising employing a network element to detect a link power-state change condition. ### Claim 31 (depends on 25) The method of claim 25, further comprising employing a network management entity to detect a link power-state change condition. ### Claim 32 (depends on 25) The method of claim 25, 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. ### Claim 33 (depends on 25) The method of claim 25, 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. ### Claim 34 (depends on 25) The method of claim 25, 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. ### Claim 35 (depends on 34) The method of claim 34, further comprising employing a link-state protocol using the utilization of the links to determine link paths in the most utilized link spanning tree. ### Claim 36 (depends on 34) The method of claim 34, 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. ### Claim 37 (depends on 34) The method of claim 34, 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. ### Claim 38 (depends on 25) The method of claim 25, 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. ### Claim 39 (depends on 38) The method of claim 38, 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. ### Claim 40 (depends on 39) The method of claim 39, 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. ### Claim 41 (depends on 39) The method of claim 39, 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. ### Claim 42 (depends on 25) The method of claim 25, 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. ### Claim 43 (depends on 42) The method of claim 42, 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. ### Claim 44 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. ### Claim 45 (depends on 44) The apparatus of claim 44, 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. ### Claim 46 (depends on 44) The apparatus of claim 44, 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. ### Claim 47 (depends on 44) The apparatus of claim 44, 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. ### Claim 48 (depends on 44) The apparatus of claim 44, 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. ### Claim 49 (depends on 44) The apparatus of claim 44, 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. ### Claim 50 A tangible non-transient machine readable medium comprising a plurality of instructions that in response to being executed by an apparatus 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. ### Claim 51 (depends on 50) The tangible non-transient machine readable medium of claim 50, 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. ### Claim 52 (depends on 50) The tangible non-transient machine readable medium of claim 50, 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. ### Claim 53 (depends on 50) The tangible non-transient machine readable medium of claim 50, 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. ### Claim 54 (depends on 50) The tangible non-transient machine readable medium of claim 50, 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.