# US 2013/0279366 A1 · Self-healing communications network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0279366 A1 - Document ID: US20130279366A1 - Status: Published application - Kind: A1 - Application number: 13/452,022 - Filed: 2012-04-20 - Published: 2013-10-24 - Earliest claimed: 2012-04-20 - Assignees: Allied Telesis Holdings K.K. - Inventors: Sachin Surendran - Web page: https://patentgrep.com/patent/US20130279366A1 ## CPC - H04L 12/462: {LAN interconnection over a bridge based backbone} - H04L 43/0811: by checking connectivity - H04L 45/18: Loop-free operations - H04L 45/38: {Flow based routing} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract The present invention encompasses methods, apparati, and computer-readable media for detecting and removing unwanted loops in communications networks having host processors (10), nodes (16), and segments (14) connecting the nodes (16). A method embodiment of the present invention comprises the steps of collecting and storing a set of steady state data regarding direction of network (1) traffic flow through the nodes (16) and segments (14) for at least one network flow; comparing newly sampled flow with stored steady state data to detect flows whose paths contradict their steady state direction; and identifying a network loop when a segment (14) carries such contradictory flows. ## Claims ### Claim 1 A method for detecting unwanted loops in a communications network having host processors, nodes, and physical or virtual segments connecting the nodes, said method comprising the steps of: collecting and storing a set of steady state data regarding direction of network traffic flow through the nodes and segments for at least one network flow; comparing newly sampled flow with stored steady state data to detect flows whose paths contradict their steady state direction; and identifying a network loop when a segment carries such contradictory flows. ### Claim 2 (depends on 1) The method of claim 1 wherein: a loop pointer is generated for each segment carrying such contradictory flows; and the loop pointers point to the unwanted loop. ### Claim 3 (depends on 1) The method of claim 1 wherein the method steps are performed by a host processor. ### Claim 4 (depends on 1) The method of claim 1 wherein the method steps are performed by a collector computer other than a host processor. ### Claim 5 (depends on 4) The method of claim 4 wherein the collector computer is coupled to the network via any form of data connectivity. ### Claim 6 (depends on 1) The method of claim 1 wherein the method steps are performed by modules associated with each node. ### Claim 7 (depends on 6) The method of claim 6 wherein: a module associated with each node determines whether there are such contradictory flows at that node; a first node experiencing such contradictory flows determines whether said node is connected to a second node experiencing such contradictory flows; and when modules associated with the first node and the second node determine that each node is experiencing contradictory flows on the same connecting segment, then a module associated with at least one node breaks the segment. ### Claim 8 (depends on 7) The method of claim 7 wherein the segment that is broken is the segment connecting the first node and the second node. ### Claim 9 (depends on 1) The method of claim 1 wherein the steady state data is collected by a flow monitoring process from the group consisting of sflow and netflow. ### Claim 10 (depends on 1) The method of claim 1 further comprising the step of disabling the segment carrying the bidirectional flows. ### Claim 11 (depends on 1) The method of claim 1 further comprising the step of breaking a lowest bandwidth segment of the loop. ### Claim 12 (depends on 1) The method of claim 1 further comprising the step of differentiating between an intentional network reconfiguration and a network loop. ### Claim 13 (depends on 12) The method of claim 12 wherein an intentional network reconfiguration is detected by observing the following two conditions: new samples of a flow in a steady state direction reduce to zero over a preselected period of time; and new samples of the flow in an opposite direction increase over said preselected period of time. ### Claim 14 (depends on 1) The method of claim 1 wherein the network is a digital packet network. ### Claim 15 (depends on 1) The method of claim 1 wherein the network is an analog network. ### Claim 16 (depends on 1) The method of claim 1 wherein a network flow contains information uniquely identifying said flow. ### Claim 17 A method for automatically healing a communications network experiencing an unwanted condition, said network having nodes coupled by segments, said method comprising at least one of the following steps: disabling a newly introduced segment that has a created a loop within the network; disabling a lowest bandwidth segment of the loop. ### Claim 18 At least one computer-readable medium comprising computer program instructions for detecting unwanted loops in a communications network having host processors, nodes, and segments connecting the nodes, said instructions adapted to effectuate the following method steps: collecting and storing a set of steady state data regarding direction of network traffic flow through the nodes and segments for at least one network flow; comparing newly sampled flow with stored steady state data to detect flows whose paths contradict their steady state direction; and identifying a network loop when a segment carries such contradictory flows. ### Claim 19 Apparatus for detecting unwanted loops in a communications network containing nodes and segments connecting the nodes, said apparatus comprising: means for collecting and storing a set of steady state data pertaining to direction of network traffic flow through the nodes and segments; coupled to the collecting and storing means, means for comparing newly sampled flows with stored steady state data to detect flows whose paths contradict their steady state direction; and coupled to the comparing means, means for detecting a network loop when a segment carries such contradictory flows.