A method for network load reduction in a polling procedure

Abstract

A method (800) for performing a polling procedure to collect information on a state, an attribute, or a setting of an individual node in a connected network (100); the method (800) comprising sending a request (S801), by a first node (110) in the connected network (100) to a second node (121-12n) in the connected network (100), with the request comprising an expected reply on the state, attribute, or setting of the second node (121-12n); sending a response (S803), by the second node (121-12n) to the first node (110), with the response comprising information on an actual state, attribute, or setting of the second node (121-12n), when the actual state, attribute, or setting is different from the expected reply (S802); and refraining from sending (S804) a response by the second node (121-12n) when the actual state, attribute, or setting of the second node (121-12n) is same as the expected reply (S802).

Description

[0001] A method for network load reduction in a polling procedure

[0002] FIELD OF THE INVENTION

[0003] The invention relates to the field of connected control systems. More particularly, various methods, apparatus, and systems are disclosed herein related to a scheme to improve the communication efficiency in a polling procedure.

[0004] BACKGROUND OF THE INVENTION

[0005] There is an ongoing trend in the professional lighting market to move more and more towards connected lighting systems, which enable all kinds of new features like (remote) scheduling, energy monitoring, sensor-based lighting control and asset management. In many cases these systems are installed in existing buildings, in which cases a wireless network is preferred to avoid having to deploy new cables (for lighting control) through the ceiling. Examples of such wireless network protocols which are used widely in current practice are open standards like Zigbee, Thread, BLE, BLE mesh, Wi-Fi, Wi-Fi direct, and various proprietary network implementations built on top of the IEEE 802.15.4, IEEE 802.15.1 or IEEE 802.11 standards.

[0006] Polling is a technique used in connected control networks to enable communication between multiple devices. In this technique, the central controller (e.g., a server) sends out requests for information to each device connected to the network. Each device then responds to the request with the requested information. Polling is commonly used in wireless control networks, where the controller is responsible for gathering data from multiple sensors or actuators. By using polling, the controller can efficiently gather data from each node in the network, without having to constantly maintain a connection with each node. In a lighting context, polling is not only important for individual light states, but also for the scene state in a room, such as to detect the current scene in a room by the states of all lamps in a room.

[0007] In many cases the connected networks can be so large that not all nodes can be reached with a direct link from a central controller, and thus those remote nodes may need the help from one or multiple relaying nodes. In bandwidth constrained networks, repeatedly requesting the status of all network nodes (polling) can result in a heavy network load that causes delay for other network traffic. Since each poll comprises a request and a response, thus two messages. Each of the message may need to go via multiple hops to between the polling device and the polled device, causing even more network traffic.

[0008] SUMMARY OF THE INVENTION

[0009] Poll-based status monitoring provides a mechanism to keep a coordinator, a central controller, or a bridge device constantly updated on any changes in the connected network. However, polling also introduces significant traffic load to a network, especially when polling needs to be implemented via multi-hop routing. The scenario becomes even worse the network scales up. On the other hand, a large proportion of polling requests return expected or unchanged status, especially for less dynamic networks such as, e.g., lighting networks.

[0010] In view of the above, the present disclosure is directed to methods, apparatus, systems, and computer programs for providing a more efficient data exchange in a polling procedure for reducing the traffic load on the connected network. More particularly, the goal of this invention is achieved by a method for performing a polling procedure as claimed in claim 1, by a connected network as claimed in claim 12, and by a computer program as claimed in claim 15.

[0011] In accordance with a first aspect of the invention a method for performing a polling procedure is provided. A method for performing a polling procedure to collect information on a state, an attribute, or a setting of an individual node in a connected network; the method comprising: sending a request, by a first node in the connected network to a second node in the connected network, with the request comprising an expected reply on the state, attribute, or setting of the second node; sending a response, by the second node to the first node, with the response comprising information on an actual state, attribute, or setting of the second node, when the actual state, attribute, or setting is different from the expected reply; and refraining from sending a response by the second node when the actual state, attribute, or setting of the second node is same as the expected reply.

[0012] To reduce the polling related traffic load, it is proposed to include an expected reply already in the polling request sent out by the polling device or the first node. And then, the polled node or the second node will only send a polling response when the actual state, attribute, or setting differs from the expected reply received in the polling request. Thus, instead of a conventional two-message polling handshake, in many cases only polling request is substantialized. As a result, the network load for polling may be reduced by up to 50%, depending on how often the state, attribute, or setting of the nodes will usually change. This can be quite significant enhancement for a large network with frequent polling messages to many nodes.

[0013] It may also be an option to replace the expected reply on the state, attribute, or setting of the second node in the polling request with a flag or indicator indicating either a response is requested, or a response is requested only when there is any change with the second node in terms of the state, attribute, or setting as compared to an earlier state, attribute, or setting reported in a previous response. In this way, the method comprising: sending a request, by a first node in the connected network to a second node in the connected network, with the request comprising a flag indicating a response is required unconditionally or a request is required only when there is any change with the second node in terms of the state, attribute, or setting as compared to an earlier state, attribute, or setting reported in a previous response; sending a response, by the second node to the first node, with the response comprising information on an actual state, attribute, or setting of the second node, when the flag in the request indicating a response is requested unconditionally or when the actual state, attribute, or setting is different from the earlier state, attribute, or setting reported in the previous response; and refraining from sending a response by the second node when the flag in the request indicating a response is requested only when there is any change with the second node in terms of the state, attribute, or setting and the actual state, attribute, or setting of the second node is same as the earlier state, attribute, or setting reported in the previous response.

[0014] Beneficially, the method further comprises a step of: upon receiving the response, updating by the first node the expected reply according to the information comprised in the response.

[0015] Basically, upon receiving the response, the fist node updates the stored state of the second node by means of the information comprised in the response. By this, the expected state for a future poll to the second node changes.

[0016] Without receiving any response to a request, the first node will consider that there is no change to the state, attribute, or setting of an individual node; otherwise, it will update the information accordingly in a local database, as well as overwrite the expected reply in a next polling request. In one example, the method further comprises a step of detecting in the connected network by the first node for the response during a first interval before resending the request to the second node.

[0017] The first interval may be determined according to one or more of the following aspects: the size of the connected network, an expected latency for receiving a response from the second node, the number of hops from the first node to the second node, the real-time or historical traffic load in the connected network, or the power budget of the first node and / or the second node.

[0018] Preferrable, the request is sent by the first node periodically.

[0019] Periodic polling helps the first node to get continuous updates on the information about individual nodes in the connected network. Alternatively, the polling procedure may also be carried out in an on-demand manner, such that a request is triggered by an event or a demand.

[0020] Beneficially, the method further comprises sending one or more further requests by the first node to one or more further nodes in the connected network one after another before detecting in the connected network for any response from the second node or from the one or more further nodes; wherein each one of the one or more further requests comprises an expected reply on the state, attribute, or setting of a corresponding node out of the one or more further nodes.

[0021] In one option, the polling request and response for each individual node are processed sequentially. Alternatively, it may also be beneficial to send a bunch of requests to multiple nodes one after another before detecting on the channel to see if there are any response from one or more nodes out of the multiple nodes. This can be quite efficient when the connected network is less dynamic, such that the states, attributes, or settings of the nodes in the network do not change frequently, and most of the time the nodes will keep silent upon receiving the polling requests. This also helps to reduce the energy consumption and time of the first node on detecting the potential responses.

[0022] Advantageously, the method further comprises a step of sending an update message by a third node after powering up with the update message comprising information related to its state, attribute, or setting.

[0023] When there is a new node added to the connected network or another node back online after restarting or powering up, it is important to include the new node or the other node also in the polling procedure for collecting information. Beneficially, the method further comprises a step, taken by a new node or a third node after powering up, of sending an update message with the update message comprising information related to its state, attribute, or setting. Such an updated message is initiated by the new node or the third node itself without a polling request, as an unrequested status update.

[0024] Advantageously, the method further comprises a step of including the third node in the polling procedure.

[0025] Upon receiving the off cycle update message, the first node or another node in the connected network will include the new node or the third node in the polling procedure, such that the new node or the third node will be polled by the first node in the same manner as other nodes included in the polling procedure.

[0026] Preferably, the connected network is a wireless network.

[0027] The connected network may be of different topologies, such as a ring topology, a tree topology, a star topology, a mesh topology, or a hybrid topology with a combination of two or more of the above topologies.

[0028] In one example, the connected network is a multi-hop network.

[0029] In one setup, the request is sent from the first node to the second node via multi-hop routing.

[0030] When the connected network has a mesh or tree topology, the request and response messages between the first node and the second node may be transmitted via multihop routing.

[0031] Beneficially, the first node is at least one of a coordinator, a central controller, a bridge, or a gateway of the connected network.

[0032] In accordance with a second aspect of the invention a connected network is provided. A connected network comprising a plurality of nodes configured to perform a polling procedure for collecting information on a state, an attribute, or a setting of an individual node in the connected network; the connected network comprising: a first node out of the plurality of node configured to send a request to a second node out of the plurality of node, with the request comprising an expected reply on the state, attribute, or setting of the second node; and the second node configured to: o send a response to the first node, with the response comprising information on an actual state, attribute, or setting of the second node, when the actual state, attribute, or setting is different from the expected reply; and o refrain from sending a response when the actual state, attribute, or setting of the second node is same as the expected reply.

[0033] The connected network may operate according to a wired communication protocol, such as Konnex (KNX), Modular Digital Communication System (MODBUS), Building Automation and Control Network (BACnet), or Digital Addressable Lighting Interface (DALI).

[0034] The connected network may operate according to a wireless communication protocol, such as to implement large scale information distribution and collection in a wireless control system with a plurality of nodes, whereas the connected network can be used for lighting control and / or building automation. It is beneficial that the wireless communication protocol supports multi-hop routing, which can be Zigbee, Thread, Bluetooth Mesh, Wi-Fi mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave, or any other mesh or tree-based technology.

[0035] In one example, the connected network may be a one-to-many network with a central controller or a gateway device and a plurality of nodes to be controlled. The control commands distributed on the network may come from the central controller locally or from the cloud via the gateway device. The central controller or the gateway device is to send out control commands in a centralized manner to the distributed network. In return, the plurality of nodes in the distributed network are configured to provide feedback to the central controller or the cloud with status information related to functional devices or actuators controlled by the central controller or the cloud. There may be other sensors, besides actuators, co-located with the plurality of nodes. Thus, the status information may also comprise sensing data or status information from other sensors. Therefore, in one preferred example, the communication in the system can be one-to-many or many-to-one.

[0036] The first node is configured to send a polling request comprising an expected reply on the state, attribute, or setting of the second node. The expected reply on the state, attribute, or setting of the second node may be derived based on a historical information, an earlier response, a default value, or a user input. The second node is configured to send a response to the first node, with the response comprising information on an actual state, attribute, or setting of the second node, when the actual state, attribute, or setting is different from the expected reply; and refrain from sending a response when the actual state, attribute, or setting of the second node is same as the expected reply.

[0037] Advantageously, the first node is further configured to: upon receiving the response, update the expected reply according to the information comprised in the response.

[0038] Therefore, when there is no response or update received from the second node, the first node will assume there is no change on the state, attribute, or setting of the second node, and the expected reply remains untouched. In such a way, the network load for polling may be reduced by up to 50%, depending on how often the state, attribute, or setting of the nodes will usually change. The less dynamic the nodes are, the more the traffic load is reduced.

[0039] In one example, the first node is further configured to: send one or more further requests, to one or more further nodes out of the plurality of nodes, one after another before detecting in the connected network for any response from the second node or from the one or more further nodes; wherein each one of the one or more further requests comprises an expected reply on the state, attribute, or setting of a corresponding node out of the one or more further nodes.

[0040] Instead of handling each polling request and response for each individual node sequentially, it may also be beneficial to send a sequence of requests to multiple nodes (thus many directly one after another), and only then detect on the channel to see if there are responses from one or more of the multiple nodes. This is especially efficient when the connected network is less dynamic, such that the states, attributes, or settings of the nodes in the network do not change frequently, and most of the time the nodes will keep silent upon receiving the polling requests. Thus, after a bunch of polling requests, the first node may occasionally receive a response from one out of the multiple nodes.

[0041] The invention may further be embodied in a computer program comprising code means which, when the program is executed by a first node or a second node according to the present invention comprising processing means, cause the processing means comprised in the first node or in the second node to perform the method according to the present invention.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the drawings, like reference characters generally refer to the same parts throughout the different figures. Also, the drawings are not necessarily to scale, emphasis instead generally being placed upon illustrating the principles of the invention.

[0044] FIG. 1 illustrates a mesh network; FIG. 2 demonstrates a connected network comprising a plurality of nodes configured to perform a polling procedure; and

[0045] FIG. 3 shows a flow chart of a method for performing a polling procedure.

[0046] DETAILED DESCRIPTION OF EMBODIMENTS

[0047] The embodiments set forth below represent information to enable those skilled in the art to practice the embodiments. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure.

[0048] FIG. 1 illustrates a mesh network. In a mesh network, devices are connected to each other directly and indirectly to allow for multiple communication paths between nodes. This means that data can be sent from one node to another through multiple routes, creating a redundant and resilient network. Mesh networks are commonly used in wireless sensor networks, home automation, and industrial applications, where reliability and flexibility are critical. As shown in FIG. 1, the mesh network may comprise a coordinator or a central controller, which is used to manage the communication between the nodes in the network, distribute and / or collect information to the nodes in the network, or act as a central point of the mesh network for interfacing with another network. There are a plurality of router nodes that are responsible for forwarding data packets between nodes in the network to enable multi-hop routing. In addition to router nodes, there is another type of nodes called end nodes, which are connected to the network but does not participate in the routing of data packets. End nodes are devices that are primarily responsible for sensing, actuating, or controlling a specific function or application. Sometimes, end nodes may have limited processing power, memory, and communication capabilities compared to router nodes or coordinator nodes. They are designed to be simple and low-cost, enabling them to be deployed in large numbers throughout a network. End nodes in a mesh network usually communicate with other nodes in the network through router nodes or a parent node. They send data packets to the network and receive data packets from the network, but they do not participate in the routing of data packets.

[0049] Polling is a communication method commonly used in control networks, where a coordinator sends requests to one or more devices to retrieve data or perform an action. The coordinator is responsible for initiating and controlling the communication between the devices in the network. In a polling-based control network, the coordinator may send requests to nodes on a regular basis. The request usually comprises information about the data to be retrieved or the action to be performed. The nodes in the control network respond to the requests with the requested data or an acknowledgement of the action performed.

[0050] Polling can be done in different ways, such as periodic polling or demand polling. In periodic polling, the coordinator polls the nodes on a regular basis, whereas in demand polling, the coordinator polls the nodes only when new data is required, or an action needs to be performed.

[0051] Polling provides a reliable and efficient method for communication between devices. However, polling can also result in delays and increased traffic on the network, which can impact the network's performance. This invention discloses an improved polling procedure with reduced overhead on traffic load.

[0052] FIG. 2 demonstrates a connected network 100 comprising a plurality of nodes 110, 121-12n configured to perform a polling procedure.

[0053] The connected network 100 can be a local network under the control of a local coordinator to serve a certain control purpose. The network can also be connected to the cloud or a backbone network, via a gateway, a bridge, or a router device.

[0054] The connected network may operate according to a wired communication protocol, such as Konnex (KNX), Modular Digital Communication System (MODBUS), Building Automation and Control Network (BACnet), or Digital Addressable Lighting Interface (DALI).

[0055] The connected network may operate according to a wireless communication protocol, such as to implement large scale information distribution and collection in a wireless control system with a plurality of nodes 110, 121-12n, whereas the connected network can be used for lighting control and / or building automation. It is beneficial that the wireless communication protocol supports multi-hop routing, which can be Zigbee, Thread, Bluetooth Mesh, Wi-Fi mesh, WirelessHART, SmartRF, CityTouch, IP500, Z-wave, or any other mesh or tree-based technology.

[0056] Considering that the control system may comprise a large number of nodes, transmission between nodes may rely on multi-hop routing. In bandwidth constrained networks, repeatedly requesting the status of all network nodes (polling) can be a heavy network load that causes delay for other network traffic. To use a Zigbee network as an example. A Zigbee network has limited bandwidth, but it may comprise a large number of nodes (up to 63 nowadays and up to 200- 255 in the near future). In order to show the actual state of all lamps in a lighting control App correctly within seconds, also for out-of-band light changes (local button, BLE, power up / down, Zigbee remote controls) which the bridge only knows via polling. Polling is not only important for individual light states, but also for the scene state in a room, and the current scene in a room is detected by the states of all lamps in a room.

[0057] Furthermore, each poll comprises a request and a response, thus two messages. Each message may go via multiple hops to the polled device and back to the polling device, each hop sequentially, causing even more network traffic. In view of this, a more efficient polling procedure is disclosed in the present invention for reducing the polling related traffic load in the network.

[0058] The first node 110 may be a coordinator, a central controller, a bridge, or a gateway of the connected network 100. The other nodes to be polled by the first node may be routers or end nodes, in a mesh network context.

[0059] In a lighting context, a node 120-12n may be comprised in a lighting device, a luminaire, a sensor, an actuator, such as a switch to serve for the communication function of the lighting device, the luminaire, the sensor, or the switch. A node 120-12n may also be comprised in a HVAC system, a smart refrigerator, a smart oven, other smart white goods, or a remote controller in a broader building / home automation context.

[0060] The first node 110 is configured to send a polling request comprising an expected reply on the state, attribute, or setting of the second node 121-12n. The expected reply on the state, attribute, or setting of the second node 121-12n may be derived based on a historical information, an earlier response, a default value, or a user input. The second node 121-12n is configured to send a response to the first node 110, with the response comprising information on an actual state, attribute, or setting of the second node 121-12n, when the actual state, attribute, or setting is different from the expected reply; and refrain from sending a response when the actual state, attribute, or setting of the second node 121-12n is same as the expected reply.

[0061] The first node 110 is further configured to upon receiving the response, update the expected reply according to the information comprised in the response. Therefore, when there is no response or update received from the second node, the first node will assume there is no change on the state, attribute, or setting of the second node, and the expected reply remains untouched. In this case, the nodes in the connected network, such as a lighting device, a luminaire, a sensor, an actuator, only responds if the state differs from the “expected state” that came with the request, and the coordinator, the central controller, the bridge, or the gateway interprets “no answer” as “state is unchanged”.

[0062] Therefore, the network load for polling may be reduced by 30-50%, depending on how often the state, attribute, or setting of the nodes will usually change. The less dynamic the nodes are, the more the traffic load is reduced.

[0063] FIG. 3 shows a flow chart of a method 800 for performing a polling procedure to collect information on a state, an attribute, or a setting of an individual node in a connected network 100. The method 800 comprises the steps of: sending a request, in step S 801, by a first node 110 in the connected network 100 to a second node 121-12n in the connected network 100, with the request comprising an expected reply on the state, attribute, or setting of the second node 121-12n; sending a response, in step S803, by the second node 121-12n to the first node 110, with the response comprising information on an actual state, attribute, or setting of the second node 121-12n, when the actual state, attribute, or setting is different from the expected reply, as determined in step S802; and refraining from sending S804 a response by the second node 121-12n when the actual state, attribute, or setting of the second node 121-12n is same as the expected reply, as determined in step S802.

[0064] Optionally, the method 800 further comprises the step S805 of upon receiving the response, updating by the first node 110 the expected reply according to the information comprised in the response.

[0065] The method 800 may further comprise the step of detecting in the connected network 100 by the first node 110 for the response during a first interval before resending the request to the second node 121-12n. The first interval may be determined according to one or more of the following aspects: the size of the connected network 100, an expected latency for receiving a response from the second node 121-12n, the number of hops from the first node 110 to the second node 121-12n, the real-time or historical traffic load in the connected network 100, or the power budget of the first node and / or the second node.

[0066] Beneficially, to get continuous updates, the request may be sent by the first node 110 periodically. The frequency of the periodic request may be determined according to one or more of the aspects on the size of the connected network 100, an expected latency for circulating a message back and forth between the first node 110 and the second node 121- 12n, the real-time or historical traffic load in the connected network 100, the power budget of the plurality of nodes 110 and 121-12n, the dynamic of the nodes in the network in terms of the speed of change on a state, an attribute, or a setting of an individual node.

[0067] Instead of handling each polling request and response for each individual node sequentially, it may also be beneficial to send a sequence of requests to multiple nodes (thus several requests directly one after another), and only then detect on the channel to see if there are responses from one or more of the multiple nodes. This is especially efficient when the connected network is less dynamic, such that the states, attributes, or settings of the nodes in the network do not change frequently, and most of the time the nodes will keep silent upon receiving the polling requests. Accordingly, the method 800 comprises the step of sending one or more further requests by the first node 110 to one or more further nodes 121-12n in the connected network 100 one after another before detecting in the connected network 100 for any response from the second node 121-12n or from the one or more further nodes 121- 12n. Each one of the one or more further requests comprises an expected reply on the state, attribute, or setting of a corresponding node out of the one or more further nodes 121-12n. Optionally, a random backoff time scheduling may be applied when one or more nodes out of the one or more further nodes 121-12n need to send a response with updated information. Thus, any potential conflict among those responses can be reduced. This option helps to further improve the efficiency of the polling procedure in the connected network.

[0068] In one scenario, there may be a new node added to the connected network or another node back online after restarting or powering up, and then it is important to include the new node or the other node also in the polling procedure for collecting information. Beneficially, the method further comprises a step, taken by a new node or a third node after powering up, of sending an update message with the update message comprising information related to its state, attribute, or setting. Such an updated message is initiated by the new node or the third node itself without a polling request, as an unrequested status update.

[0069] Upon receiving the off cycle update message, the first node or another node in the connected network will include the new node or the third node in the polling procedure, such that the new node or the third node will be polled by the first node in the same manner as other nodes included in the polling procedure.

[0070] The method according to the present invention may be implemented on a computer as a computer implemented method, or in dedicated hardware, or in a combination of both. Executable code for a method according to the invention may be stored on computer / machine readable storage means. Examples of computer / machine readable storage means include non-volatile memory devices, optical storage medium / devices, solid-state media, integrated circuits, servers, etc. Preferably, the computer program product comprises non-transitory program code means stored on a computer readable medium for performing a method according to the invention when said program product is executed on a computer or a processing means comprised in a node or a network or a commissioning device as disclosed in the above-described embodiments.

[0071] Methods, systems and computer-readable media (transitory and non- transitory) may also be provided to implement selected aspects of the above-described embodiments.

[0072] The term “controller” is used herein generally to describe various apparatus relating to, among other functions, the operation of one or more network devices or coordinators. A controller can be implemented in numerous ways (e.g., such as with dedicated hardware) to perform various functions discussed herein. A “processor” is one example of a controller which employs one or more microprocessors that may be programmed using software (e.g., microcode) to perform various functions discussed herein. A controller may be implemented with or without employing a processor, and also may be implemented as a combination of dedicated hardware to perform some functions and a processor (e.g., one or more programmed microprocessors and associated circuitry) to perform other functions. Examples of controller components that may be employed in various embodiments of the present disclosure include, but are not limited to, conventional microprocessors, application specific integrated circuits (ASICs), and field-programmable gate arrays (FPGAs).

[0073] In various implementations, a processor or controller may be associated with one or more storage media (generically referred to herein as “memory,” e.g., volatile and non-volatile computer memory such as RAM, PROM, EPROM, and EEPROM, compact disks, optical disks, etc.). In some implementations, the storage media may be encoded with one or more programs that, when executed on one or more processors and / or controllers, perform at least some of the functions discussed herein. Various storage media may be fixed within a processor or controller or may be transportable, such that the one or more programs stored thereon can be loaded into a processor or controller so as to implement various aspects of the present invention discussed herein. The terms “program” or “computer program” are used herein in a generic sense to refer to any type of computer code (e.g., software or microcode) that can be employed to program one or more processors or controllers.

[0074] The term “network” as used herein refers to any interconnection of two or more devices (including controllers or processors) that facilitates the transport of information (e.g. for device control, data storage, data exchange, etc.) between any two or more devices and / or among multiple devices coupled to the network.

Claims

CLAIMS:

1. A method (800) for performing a polling procedure to collect information on a state, an attribute, or a setting of an individual node in a connected network (100); the method (800) comprising: sending a request (S801), by a first node (110) in the connected network (100) to a second node (121-12n) in the connected network (100), with the request comprising an expected reply on the state, attribute, or setting of the second node (121-12n); sending a response (S803), by the second node (121-12n) to the first node(110), with the response comprising information on an actual state, attribute, or setting of the second node (121-12n), when the actual state, attribute, or setting is different from the expected reply (S802); and refraining from sending (S804) a response by the second node (121-12n) when the actual state, attribute, or setting of the second node (121-12n) is same as the expected reply (S802).

2. The method (800) of claim 1 further comprising the step of: upon receiving the response, updating (S805) by the first node (110) the expected reply according to the information comprised in the response.

3. The method (800) of claim 1 or 2 further comprising detecting in the connected network (100) by the first node (110) for the response during a first interval before resending the request to the second node (121-12n).

4. The method (800) of any one of previous claims, wherein the request is sent by the first node (110) periodically.

5. The method (800) of any one of previous claims further comprising sending one or more further requests by the first node (110) to one or more further nodes (121-12n) in the connected network (100) one after another before detecting in the connected network (100) for any response from the second node (121 -12n) or from the one or more further nodes(121-12n); wherein each one of the one or more further requests comprises an expected reply on the state, attribute, or setting of a corresponding node out of the one or more further nodes (121-12n).

6. The method (800) of any one of previous claims further comprising sending an update message by a third node after powering up with the update message comprising information related to its state, attribute, or setting.

7. The method (800) of claim 6 further comprising including the third node in the polling procedure.

8. The method (800) of any one of previous claims, wherein the connected network (100) is a wireless network (100).

9. The method (800) of any one of previous claims, wherein the connected network (100) is a multi-hop network (100).

10. The method (800) of claim 9, wherein the request is sent from the first node (110) to the second node (121-12n) via multi-hop routing.

11. The method (800) of any one of previous claims, wherein the first node (110) is at least one of a coordinator, a central controller, a bridge, or a gateway of the connected network (100).

12. A connected network (100) comprising a plurality of nodes (110, 121-12n) configured to perform a polling procedure for collecting information on a state, an attribute, or a setting of an individual node in the connected network (100); the connected network (100) comprising: a first node (110) out of the plurality of node configured to send a request to a second node out of the plurality of node (110, 121-12n), with the request comprising an expected reply on the state, attribute, or setting of the second node (121-12n); and the second node (121-12n) configured to: o send a response to the first node (110), with the response comprising information on an actual state, attribute, or setting of the second node(121-12n), when the actual state, attribute, or setting is different from the expected reply; and o refrain from sending a response when the actual state, attribute, or setting of the second node (121-12n) is same as the expected reply.

13. The connected network (100) of claim 12, wherein the first node (110) is further configured to: upon receiving the response, update the expected reply according to the information comprised in the response.

14. The connected network (100) of claim 12 or 13, wherein the first node (110) is further configured to: send one or more further requests, to one or more further nodes (121-12n) out of the plurality of nodes, one after another before detecting in the connected network (100) for any response from the second node (121-12n) or from the one or more further nodes; wherein each one of the one or more further requests comprises an expected reply on the state, attribute, or setting of a corresponding node out of the one or more further nodes (121- 12n).

15. A computing program comprising code means which, when the program is executed by a first node (110) or a second node (121-12n) according to claim 12 comprising processing means, cause the processing means comprised in the first node (110) or in the second node (121-12n) to perform the method (800) of claims 1-11.

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