Patent Description:
Options for accessing and listening to digital audio in an out-loud setting were limited until in <NUM>, when SONOS, Inc. filed for one of its first patent applications, entitled "Method for Synchronizing Audio Playback between Multiple Networked Devices," and began offering a media playback system for sale in <NUM>. The Sonos Wireless HiFi System enables people to experience music from many sources via one or more networked playback devices. Through a software control application installed on a smartphone, tablet, or computer, one can play what he or she wants in any room that has a networked playback device. Additionally, using the controller, for example, different songs can be streamed to each room with a playback device, rooms can be grouped together for synchronous playback, or the same song can be heard in all rooms synchronously.

Given the ever growing interest in digital media, there continues to be a need to develop consumer-accessible technologies to further enhance the listening experience.

<CIT> describes assisting wireless devices, such as dependent devices, in connecting to an access point or associated wireless network. A dependent device requests assistance from another device to connect to the wireless network.

According to a first aspect of the present invention, there is provided a method as defined in appended claim <NUM>. According to a second aspect of the present invention, there is provided a computer readable medium as defined in appended claim <NUM>. According to a third aspect of the present invention, there is provided a playback device as defined in appended claim <NUM>.

The drawings are for the purpose of illustrating example embodiments, but it is understood that the inventions are not limited to the arrangements and instrumentality shown in the drawings.

Example implementations described herein involve, inter alia, techniques to re-establish network connectivity of a playback device to a media playback system when the playback device is in a "lost" state. Example media playback systems include multiple network-interconnected devices (e.g., one or more playback devices to play back media and/or one or more control devices to control playback by the one or more playback devices). To promote network stability, playback devices of such example media playback systems store network parameters in a file in data storage and utilize these parameters to establish a network connection.

However, utilizing network parameters in a stored file creates a potential for those parameters to become "stale" (i.e., different) from the current network parameters in use by the network. A playback device of a media playback system may enter a "lost" state when the playback device cannot establish a connection to the media playback system because its stored network parameters are "stale. " For example, while a given playback device of a media playback system is powered down, the media playback system may change the wireless channel for its network. When the playback device is powered back up and attempts to establish a connected using its stored network parameters, the playback device will be unable to establish a network connection because the playback device is attempting to use the previous wireless channel.

In contrast to the example playback devices described above, other network client devices obtain network parameters dynamically from a router or gateway (e.g., a Dynamic Host Configuration Protocol (DHCP)) server). Initially, such a client device may obtain network parameters via a discovery process. After a power-cycle, the client device may re-obtain the network parameters from the router or gateway. In such an example, since the client device isn't using network parameters stored in a file in data storage, the network parameters do not become stale and the client device avoids getting lost. However, because the network parameters are obtained dynamically, certain parameters (like the client IP address) are not as stable as when a client device (e.g., a playback device) utilizes network parameters that are stored in a file on the client device. As an example of less stability, the client device might obtain a different IP address when re-obtaining the network parameters from the router or gateway.

In some example techniques, a first playback device of a media playback device may re-establish network connectivity by obtaining network parameters from a second playback device of the media playback system. In an example, the first playback device determines that the first playback device is in a "lost" state, i.e., that the first playback device has lost its connection to the network. As a result, the first playback device searches for a second playback device that is not in the "lost" state, i.e., that the second playback device has a valid network connection. The first playback device may search for the second playback device by broadcasting a probe message. In response to receiving such a probe message, a second playback device may send a response message back to the first playback device. The response message (and/or one or more subsequent message from the second playback device) includes data representing network parameters utilized by the second playback device. Upon receiving such network parameters, the first playback device adopts the network parameters represented in the received message(s) to re-establish network connectivity.

As indicated above, example media playback systems may include one or more control devices to control playback by the one or more playback devices. Such control devices may control the playback device(s) by transmitting commands over a network via a network interface. As such, when a playback device becomes "lost" (i.e., loses network connectivity), the control devices may have limited (or no) ability to control the playback device. Moreover, in some implementations, the playback devices themselves have a limited control interface. For instance, an example playback device may include transport controls (e.g., play/pause, skip) and volume controls but exclude a touch-screen display or other control interface suitable for establishing (or re-establishing) a network connection. As such, example techniques described herein may facilitate such a playback device re-establishing network connectivity without user input by obtaining network parameters from another playback device when the playback device detects that it has become "lost.

Further, in some implementations, each network parameters file on a respective playback device has a respective version number, which may facilitate a playback device utilizing the most recent network parameters available. For instance, after temporarily re-establishing network connectivity using network parameters from a second playback device, a first playback device may determine the most recent network parameters of the media playback system. To determine the most recent network parameters of the media playback system, the first playback device may receive network parameters (and corresponding version numbers) from multiple playback devices within the network.

Given that each playback device increments the version number of its respective network parameters file when updating the network parameters stored in that file, the first playback device may determine the most recent parameters by identifying the network parameters having the most recent version number. If the first playback device finds more up-to-date network parameters, the first playback device updates its network parameters file and utilizes those network parameters. The first playback device also replicates these network parameters to other playback devices within the media playback system, to facilitate each playback device having the most recent parameters.

As noted above, example techniques may involve re-establishing network connectivity of a playback device to a media playback system. A first implementation may include accessing, from a file stored in data storage of the first playback device, first network parameters comprising: (i) a service set identifier (SSID) identifying a first wireless local area network (WLAN); (ii) a wireless channel; (iii) an IP address for the network interface, wherein the first playback device previously established a valid network connection over the first WLAN using the first network parameters. The first implementation may also include determining that the first playback device is unable to establish a valid network connection to the first WLAN using the first network parameters, wherein determining that the first playback device is unable to establish a valid network connection to the first WLAN comprises attempting to connect to the first WLAN via the wireless network interface using the first network parameter, and in response to determining that the first playback device is unable to establish the valid network connection to the first WLAN, broadcasting, via the network interface, a probe request message over multiple wireless channels. The first implementation may further include receiving, via the wireless network interface from a second playback device, a response to the probe request message, the response to the probe request message indicating second network parameters that are assigned to a network interface of the second playback device to establish a valid network connection to a particular WLAN, wherein the particular WLAN is one of: (a) the first WLAN or (b) a second WLAN, and wherein the second wireless parameters comprise a wireless channel of the particular WLAN. The first implementation may include establishing, via the wireless network interface, a valid network connection to the particular WLAN using the second network parameters; and joining, via the established valid network connection to the particular WLAN, a media playback system that comprises the second playback device, wherein the first playback device is configured to play back audio content using the established valid connection to the particular WLAN.

A second implementation may involve a first playback device connected via a wired connection to an access point and a second playback device configured to connect to the access point via a wireless point-to-point connection to the first playback device. The second implementation may include determining that the second playback device is unable to establish a valid network connection to the access point via the wireless point-to-point connection to the first playback device using first network parameters, and in response to determining that the second playback device is unable to establish the valid network connection to the access point, broadcasting, via a network interface of the second playback device, a probe request message over multiple wireless channels. The second implementation may also include receiving, via the wireless network interface from the first playback device, a response to the probe request message, the response to the probe request message indicating second network parameters assigned to a network interface of the first playback device, wherein the second network parameters are different from the first network parameters. The second implementation may further include establishing, via the wireless network interface, a valid network connection to the access point via the wireless point-to-point connection to the first playback device using the second network parameters.

A third implementation may involve a first playback device connected via a wired connection to a first access point that is configured to assign IP addresses in a first subnet; a second playback device connected via a wired connection to a network device, wherein the network device is not an access point; and a third playback device configured to connect to the first access point via a wireless point-to-point connection to the first playback device. The third implementation may include determining that the first access point has been replaced with a second access point, wherein the second access point is configured to assign IP addresses in a second subnet that covers a different IP address range than the first subnet, and in response to determining that the first access point has been replaced with the second access point, connecting, via a network interface of the third playback device, to the second access point. The third implementation may further include after connecting to the second access point, requesting, via the network interface of the third playback device, an IP address in the second subnet. The third implementation may also include establishing, via the network interface of the third playback device, a network connection to the second access point via a wireless point-to-point connection to the first playback device using the IP address in the second subnet.

Each of the these example implementations may be embodied as a method, a device configured to carry out the implementation, a system of devices configured to carry out the implementation, or a non-transitory computer-readable medium containing instructions that are executable by one or more processors to carry out the implementation, among other examples. It will be understood by one of ordinary skill in the art that this disclosure includes numerous other embodiments, including combinations of the example features described herein. Further, any example operation described as being performed by a given device to illustrate a technique may be performed by any suitable devices, including the devices described herein. Yet further, any device may cause another device to perform any of the operations described herein.

While some examples described herein may refer to functions performed by given actors such as "users" and/or other entities, it should be understood that this description is for purposes of explanation only. The claims should not be interpreted to require action by any such example actor unless explicitly required by the language of the claims themselves.

Some operations are described herein as being performed "in response to" another operation. For purposes of this disclosure, an operation performed "in response to" another operation is intended to describe an operation performed as a necessary result of the other operation. However, an operation performed "in response to" another operation need not necessarily be performed immediately following the other operation. For instance, a device may perform a first operation, then perform one or more second operations, and then perform a third operation in response to the third operation. Moreover, an given operation performed in response to a certain operation may also be performed based on other operations, but the given operation is intended to be a necessary result of the certain operation.

<FIG> illustrates an example configuration of a media playback system <NUM> in which one or more embodiments disclosed herein may be practiced or implemented. The media playback system <NUM> as shown is associated with an example home environment having several rooms and spaces, such as for example, a master bedroom, an office, a dining room, and a living room. As shown in the example of <FIG>, the media playback system <NUM> includes playback devices <NUM>-<NUM>, control devices <NUM> and <NUM>, and a wired or wireless network router <NUM>.

<FIG> shows a functional block diagram of an example playback device <NUM> that may be configured to be one or more of the playback devices <NUM>-<NUM> of the media playback system <NUM> of <FIG>. The playback device <NUM> may include a processor <NUM>, software components <NUM>, memory <NUM>, audio processing components <NUM>, audio amplifier(s) <NUM>, speaker(s) <NUM>, and a network interface <NUM> including wireless interface(s) <NUM> and wired interface(s) <NUM>. In one case, the playback device <NUM> may not include the speaker(s) <NUM>, but rather a speaker interface for connecting the playback device <NUM> to external speakers. In another case, the playback device <NUM> may include neither the speaker(s) <NUM> nor the audio amplifier(s) <NUM>, but rather an audio interface for connecting the playback device <NUM> to an external audio amplifier or audio-visual receiver.

In one example, the processor <NUM> may be a clock-driven computing component configured to process input data according to instructions stored in the memory <NUM>. The memory <NUM> may be a tangible computer-readable medium configured to store instructions executable by the processor <NUM>. For instance, the memory <NUM> may be data storage that can be loaded with one or more of the software components <NUM> executable by the processor <NUM> to achieve certain functions. In one example, the functions may involve the playback device <NUM> retrieving audio data from an audio source or another playback device. In another example, the functions may involve the playback device <NUM> sending audio data to another device or playback device on a network. In yet another example, the functions may involve pairing of the playback device <NUM> with one or more playback devices to create a multi-channel audio environment.

Certain functions may involve the playback device <NUM> synchronizing playback of audio content with one or more other playback devices. During synchronous playback, a listener will preferably not be able to perceive time-delay differences between playback of the audio content by the playback device <NUM> and the one or more other playback devices. <CIT> entitled, "System and method for synchronizing operations among a plurality of independently clocked digital data processing devices" provides in more detail some examples for audio playback synchronization among playback devices.

The memory <NUM> may further be configured to store data associated with the playback device <NUM>, such as one or more zones and/or zone groups the playback device <NUM> is a part of, audio sources accessible by the playback device <NUM>, or a playback queue that the playback device <NUM> (or some other playback device) may be associated with. The data may be stored as one or more state variables that are periodically updated and used to describe the state of the playback device <NUM>. The memory <NUM> may also include the data associated with the state of the other devices of the media system, and shared from time to time among the devices so that one or more of the devices have the most recent data associated with the system. Other embodiments are also possible.

The audio processing components <NUM> may include one or more digital-to-analog converters (DAC), an audio preprocessing component, an audio enhancement component or a digital signal processor (DSP), and so on. In one embodiment, one or more of the audio processing components <NUM> may be a subcomponent of the processor <NUM>. In one example, audio content may be processed and/or intentionally altered by the audio processing components <NUM> to produce audio signals. The produced audio signals may then be provided to the audio amplifier(s) <NUM> for amplification and playback through speaker(s) <NUM>. Particularly, the audio amplifier(s) <NUM> may include devices configured to amplify audio signals to a level for driving one or more of the speakers <NUM>. The speaker(s) <NUM> may include an individual transducer (e.g., a "driver") or a complete speaker system involving an enclosure with one or more drivers. A particular driver of the speaker(s) <NUM> may include, for example, a subwoofer (e.g., for low frequencies), a mid-range driver (e.g., for middle frequencies), and/or a tweeter (e.g., for high frequencies). In some cases, each transducer in the one or more speakers <NUM> may be driven by an individual corresponding audio amplifier of the audio amplifier(s) <NUM>. In addition to producing analog signals for playback by the playback device <NUM>, the audio processing components <NUM> may be configured to process audio content to be sent to one or more other playback devices for playback.

Audio content to be processed and/or played back by the playback device <NUM> may be received from an external source, such as via an audio line-in input connection (e.g., an auto-detecting <NUM> audio line-in connection) or the network interface <NUM>.

The network interface <NUM> may be configured to facilitate a data flow between the playback device <NUM> and one or more other devices on a data network. As such, the playback device <NUM> may be configured to receive audio content over the data network from one or more other playback devices in communication with the playback device <NUM>, network devices within a local area network, or audio content sources over a wide area network such as the Internet. In one example, the audio content and other signals transmitted and received by the playback device <NUM> may be transmitted in the form of digital packet data containing an Internet Protocol (IP)-based source address and IP-based destination addresses. In such a case, the network interface <NUM> may be configured to parse the digital packet data such that the data destined for the playback device <NUM> is properly received and processed by the playback device <NUM>.

As shown, the network interface <NUM> may include wireless interface(s) <NUM> and wired interface(s) <NUM>. The wireless interface(s) <NUM> may provide network interface functions for the playback device <NUM> to wirelessly communicate with other devices (e.g., other playback device(s), speaker(s), receiver(s), network device(s), control device(s) within a data network the playback device <NUM> is associated with) in accordance with a communication protocol (e.g., any wireless standard including IEEE <NUM>. 11a, <NUM>. 11b, <NUM>, <NUM>. 11n, <NUM>. 11ac, <NUM>, <NUM> mobile communication standard, and so on). The wired interface(s) <NUM> may provide network interface functions for the playback device <NUM> to communicate over a wired connection with other devices in accordance with a communication protocol (e.g., IEEE <NUM>). While the network interface <NUM> shown in <FIG> includes both wireless interface(s) <NUM> and wired interface(s) <NUM>, the network interface <NUM> may in some embodiments include only wireless interface(s) or only wired interface(s).

In one example, the playback device <NUM> and one other playback device may be paired to play two separate audio components of audio content. For instance, playback device <NUM> may be configured to play a left channel audio component, while the other playback device may be configured to play a right channel audio component, thereby producing or enhancing a stereo effect of the audio content. The paired playback devices (also referred to as "bonded playback devices") may further play audio content in synchrony with other playback devices.

In another example, the playback device <NUM> may be sonically consolidated with one or more other playback devices to form a single, consolidated playback device. A consolidated playback device may be configured to process and reproduce sound differently than an unconsolidated playback device or playback devices that are paired, because a consolidated playback device may have additional speaker drivers through which audio content may be rendered. For instance, if the playback device <NUM> is a playback device designed to render low frequency range audio content (i.e. a subwoofer), the playback device <NUM> may be consolidated with a playback device designed to render full frequency range audio content. In such a case, the full frequency range playback device, when consolidated with the low frequency playback device <NUM>, may be configured to render only the mid and high frequency components of audio content, while the low frequency range playback device <NUM> renders the low frequency component of the audio content. The consolidated playback device may further be paired with a single playback device or yet another consolidated playback device.

By way of illustration, SONOS, Inc. presently offers (or has offered) for sale certain playback devices including a "PLAY:<NUM>," "PLAY:<NUM>," "PLAY:<NUM>," "PLAYBAR," "CONNECT:AMP," "CONNECT," and "SUB. " Any other past, present, and/or future playback devices may additionally or alternatively be used to implement the playback devices of example embodiments disclosed herein. Additionally, it is understood that a playback device is not limited to the example illustrated in <FIG> or to the SONOS product offerings. For example, a playback device may include a wired or wireless headphone. In another example, a playback device may include or interact with a docking station for personal mobile media playback devices. In yet another example, a playback device may be integral to another device or component such as a television, a lighting fixture, or some other device for indoor or outdoor use.

Referring back to the media playback system <NUM> of <FIG>, the environment may have one or more playback zones, each with one or more playback devices. The media playback system <NUM> may be established with one or more playback zones, after which one or more zones may be added, or removed to arrive at the example configuration shown in <FIG>. Each zone may be given a name according to a different room or space such as an office, bathroom, master bedroom, bedroom, kitchen, dining room, living room, and/or balcony. In one case, a single playback zone may include multiple rooms or spaces. In another case, a single room or space may include multiple playback zones.

As shown in <FIG>, the balcony, dining room, kitchen, bathroom, office, and bedroom zones each have one playback device, while the living room and master bedroom zones each have multiple playback devices. In the living room zone, playback devices <NUM>, <NUM>, <NUM>, and <NUM> may be configured to play audio content in synchrony as individual playback devices, as one or more bonded playback devices, as one or more consolidated playback devices, or any combination thereof. Similarly, in the case of the master bedroom, playback devices <NUM> and <NUM> may be configured to play audio content in synchrony as individual playback devices, as a bonded playback device, or as a consolidated playback device.

In one example, one or more playback zones in the environment of <FIG> may each be playing different audio content. For instance, the user may be grilling in the balcony zone and listening to hip hop music being played by the playback device <NUM> while another user may be preparing food in the kitchen zone and listening to classical music being played by the playback device <NUM>. In another example, a playback zone may play the same audio content in synchrony with another playback zone. For instance, the user may be in the office zone where the playback device <NUM> is playing the same rock music that is being playing by playback device <NUM> in the balcony zone. In such a case, playback devices <NUM> and <NUM> may be playing the rock music in synchrony such that the user may seamlessly (or at least substantially seamlessly) enjoy the audio content that is being played out-loud while moving between different playback zones. Synchronization among playback zones may be achieved in a manner similar to that of synchronization among playback devices, as described in previously referenced <CIT>.

Further, different playback zones of the media playback system <NUM> may be dynamically combined into zone groups or split up into individual playback zones. For instance, the dining room zone and the kitchen zone <NUM> may be combined into a zone group for a dinner party such that playback devices <NUM> and <NUM> may render audio content in synchrony. On the other hand, the living room zone may be split into a television zone including playback device <NUM>, and a listening zone including playback devices <NUM>, <NUM>, and <NUM>, if the user wishes to listen to music in the living room space while another user wishes to watch television.

<FIG> shows a functional block diagram of an example control device <NUM>, not covered by the claimed invention, that may be configured to be one or both of the control devices <NUM> and <NUM> of the media playback system <NUM>. Control device <NUM> may also be referred to as a controller <NUM>. As shown, the control device <NUM> may include a processor <NUM>, memory <NUM>, a network interface <NUM>, and a user interface <NUM>. In one example, the control device <NUM> may be a dedicated controller for the media playback system <NUM>. In another example, the control device <NUM> may be a network device on which media playback system controller application software may be installed, such as for example, an iPhone™, iPad™ or any other smart phone, tablet or network device (e.g., a networked computer such as a PC or Mac™).

The processor <NUM> may be configured to perform functions relevant to facilitating user access, control, and configuration of the media playback system <NUM>. The memory <NUM> may be configured to store instructions executable by the processor <NUM> to perform those functions. The memory <NUM> may also be configured to store the media playback system controller application software and other data associated with the media playback system <NUM> and the user.

In one example, the network interface <NUM> may be based on an industry standard (e.g., infrared, radio, wired standards including IEEE <NUM>, wireless standards including IEEE <NUM>1a, <NUM>. 11b, <NUM>, <NUM>. 11n, <NUM>. 11ac, <NUM>, <NUM> mobile communication standard, and so on). The network interface <NUM> may provide a means for the control device <NUM> to communicate with other devices in the media playback system <NUM>. In one example, data and information (e.g., such as a state variable) may be communicated between control device <NUM> and other devices via the network interface <NUM>. For instance, playback zone and zone group configurations in the media playback system <NUM> may be received by the control device <NUM> from a playback device or another network device, or transmitted by the control device <NUM> to another playback device or network device via the network interface <NUM>. In some cases, the other network device may be another control device.

Playback device control commands such as volume control and audio playback control may also be communicated from the control device <NUM> to a playback device via the network interface <NUM>. As suggested above, changes to configurations of the media playback system <NUM> may also be performed by a user using the control device <NUM>. The configuration changes may include adding/removing one or more playback devices to/from a zone, adding/removing one or more zones to/from a zone group, forming a bonded or consolidated player, separating one or more playback devices from a bonded or consolidated player, among others. Accordingly, the control device <NUM> may sometimes be referred to as a controller, whether the control device <NUM> is a dedicated controller or a network device on which media playback system controller application software is installed.

The user interface <NUM> of the control device <NUM> may be configured to facilitate user access and control of the media playback system <NUM>, by providing a controller interface such as the controller interface <NUM>, not covered by the claimed invention, shown in <FIG>. The controller interface <NUM> includes a playback control region <NUM>, a playback zone region <NUM>, a playback status region <NUM>, a playback queue region <NUM>, and an audio content sources region <NUM>. The user interface <NUM> as shown is just one example of a user interface that may be provided on a network device such as the control device <NUM> of <FIG> (and/or the control devices <NUM> and <NUM> of <FIG>) and accessed by users to control a media playback system such as the media playback system <NUM>. Other user interfaces of varying formats, styles, and interactive sequences may alternatively be implemented on one or more network devices to provide comparable control access to a media playback system.

For example, as shown, a "group" icon may be provided within each of the graphical representations of playback zones. The "group" icon provided within a graphical representation of a particular zone may be selectable to bring up options to select one or more other zones in the media playback system to be grouped with the particular zone. Once grouped, playback devices in the zones that have been grouped with the particular zone will be configured to play audio content in synchrony with the playback device(s) in the particular zone. Analogously, a "group" icon may be provided within a graphical representation of a zone group. In this case, the "group" icon may be selectable to bring up options to deselect one or more zones in the zone group to be removed from the zone group. Other interactions and implementations for grouping and ungrouping zones via a user interface such as the user interface 400A are also possible. The representations of playback zones in the playback zone region <NUM> may be dynamically updated as playback zone or zone group configurations are modified.

The playback status region <NUM> may include graphical representations of audio content that is presently being played, previously played, or scheduled to play next in the selected playback zone or zone group. The selected playback zone or zone group may be visually distinguished on the user interface, such as within the playback zone region <NUM> and/or the playback status region <NUM>. The graphical representations may include track title, artist name, album name, album year, track length, and other relevant information that may be useful for the user to know when controlling the media playback system via the user interface 400A.

Referring back to the user interface 400A of <FIG>, the graphical representations of audio content in the playback queue region <NUM> may include track titles, artist names, track lengths, and other relevant information associated with the audio content in the playback queue. In one example, graphical representations of audio content may be selectable to bring up additional selectable icons to manage and/or manipulate the playback queue and/or audio content represented in the playback queue. For instance, a represented audio content may be removed from the playback queue, moved to a different position within the playback queue, or selected to be played immediately, or after any currently playing audio content, among other possibilities. A playback queue associated with a playback zone or zone group may be stored in a memory on one or more playback devices in the playback zone or zone group, on a playback device that is not in the playback zone or zone group, and/or some other designated device. Playback of such a playback queue may involve one or more playback devices playing back media items of the queue, perhaps in sequential or random order.

<FIG> depicts a smartphone <NUM> that includes one or more processors, a tangible computer-readable memory, a network interface, and a display. Smartphone <NUM> might be an example implementation of control device <NUM> or <NUM> of <FIG>, or control device <NUM> of <FIG>, or other control devices described herein. By way of example, reference will be made to smartphone <NUM> and certain control interfaces, prompts, and other graphical elements that smartphone <NUM> may display when operating as a control device of a media playback system (e.g., of media playback system <NUM>). Within examples, such interfaces and elements may be displayed by any suitable control device, such as a smartphone, tablet computer, laptop or desktop computer, personal media player, or a remote control device.

While operating as a control device of a media playback system, smartphone <NUM> may display one or more controller interface, such as controller interface <NUM>. Similar to playback control region <NUM>, playback zone region <NUM>, playback status region <NUM>, playback queue region <NUM>, and/or audio content sources region <NUM> of <FIG>, smartphone <NUM> might display one or more respective interfaces, such as a playback control interface, a playback zone interface, a playback status interface, a playback queue interface, and/or an audio content sources interface. Example control devices might display separate interfaces (rather than regions) where screen size is relatively limited, such as with smartphones or other handheld devices.

As indicated previously, one or more playback devices in a zone or zone group may be configured to retrieve for playback audio content (e.g., according to a corresponding URI or URL for the audio content) from a variety of available audio content sources. In one example, audio content may be retrieved by a playback device directly from a corresponding audio content source (e.g., a line-in connection). In another example, audio content may be provided to a playback device over a network via one or more other playback devices or network devices.

Example audio content sources may include a memory of one or more playback devices in a media playback system such as the media playback system <NUM> of <FIG>, local music libraries on one or more network devices (such as a control device, a network-enabled personal computer, or a networked-attached storage (NAS), for example), streaming audio services providing audio content via the Internet (e.g., the cloud), or audio sources connected to the media playback system via a line-in input connection on a playback device or network devise, among other possibilities.

Moving now to several example implementations, implementations <NUM>, <NUM>, and <NUM> shown in <FIG>, <FIG>, and <FIG>, respectively present example embodiments of techniques described herein. These example embodiments that can be implemented within an operating environment including, for example, the media playback system <NUM> of <FIG>, one or more of the playback device <NUM> of <FIG>, or one or more of the control device <NUM> of <FIG>. Further, operations illustrated by way of example as being performed by a media playback system can be performed by any suitable device, such as a playback device or a control device of a media playback system. Implementations <NUM>, <NUM>, and <NUM> may include one or more operations, functions, or actions as illustrated by one or more of blocks shown in <FIG>, <FIG> and <FIG>. Although the blocks are illustrated in sequential order, these blocks may also be performed in parallel, and/or in a different order than those described herein. Also, the various blocks may be combined into fewer blocks, divided into additional blocks, and/or removed based upon the desired implementation.

In addition, for the implementations disclosed herein, the flowcharts show functionality and operation of one possible implementation of present embodiments. In this regard, each block may represent a module, a segment, or a portion of program code, which includes one or more instructions executable by a processor for implementing specific logical functions or steps in the process. The program code may be stored on any type of computer readable medium, for example, such as a storage device including a disk or hard drive. The computer readable medium may include non-transitory computer readable medium, for example, such as computer-readable media that stores data for short periods of time like register memory, processor cache, and Random Access Memory (RAM). The computer readable medium may also include non-transitory media, such as secondary or persistent long term storage, like read only memory (ROM), optical or magnetic disks, compact-disc read only memory (CD-ROM), for example. The computer readable media may also be any other volatile or non-volatile storage systems. The computer readable medium may be considered a computer readable storage medium, for example, or a tangible storage device. In addition, for the implementations disclosed herein, each block may represent circuitry that is wired to perform the specific logical functions in the process.

As indicated above, some example techniques may involve a playback device re-establishing network connectivity. <FIG> presents an implementation <NUM> to facilitate a first playback device establishing network connectivity using network parameters of a second playback device.

At block <NUM>, implementation <NUM> involves accessing first network parameters from a file stored in data storage of a first playback device. According to the invention, a first playback device (e.g., any playback device shown in <FIG> or playback device <NUM> of <FIG>) retrieves, from a file stored in data storage of the first playback device (e.g., memory <NUM>), first network parameters. The first playback device may retrieve the first network parameters by performing a read operation on the file stored in data storage, so as to retrieve the first network parameters from characters, symbols, or other data structures representing the first network parameters.

The first network parameters stored in the file include network settings that the first playback device previously used to establish a valid network connection to a first local area network (e.g., a first wireless local area network (WLAN)). In other words, at least at a previous point-in-time, the network parameters stored in the file represented settings that, when used with a network interface of the first playback device, enabled the first playback device to establish a valid network connection to the first local area network. However, when the first playback device retrieves the first network parameters, changes external to the first playback device (e.g., changes to the first local area network), may have caused the first network parameters to become "stale," such that the first playback device is no longer able to establish a valid network connection to the first local area network using the first network parameters.

The file may include various network parameters sufficient to establish a network connection to a local area network. For instance, the network parameters may include an IP address for the first playback device, as well as a gateway address. For a wireless local area network, the network parameters may include a service set identifier (SSID) that identifies the first wireless local area network and a wireless channel (e.g., a wireless channel on the <NUM> or <NUM> bands). If the network is secured using a protocol such as Wi-Fi Protected Access (WPA), the network parameters may also include wireless security settings, such as a security key. Other example network parameters include a media access control (MAC) address and a subnet mask. In some implementations, the file may include an address for a DHCP server, a subnet mask, and DHCP lease information (e.g., when a lease was obtained from the DHCP server and/or when the lease expires). Other network parameters could be stored in the file as well.

As indicated above, example first playback devices establish a network connection to perform operations such as receiving control commands from a control device (e.g., control device <NUM>) or to retrieve media content for playback. As such, in preparation for such operations, the first playback device may access the first network parameters as part of a power-on or boot-up sequence after a power cycle. After accessing the first network parameters (perhaps in response to accessing the first network parameters), the first playback device may attempt to establish a network connection using those first network parameters.

<FIG> illustrates an example system <NUM> in which implementation <NUM> (as well as other implementations described herein) may be practiced. As shown, system <NUM> includes playback device <NUM>, playback device <NUM>, and playback device <NUM>. Playback device <NUM>, playback device <NUM>, and playback device <NUM> may represent playback devices of a media playback system that are interconnected via a local area network provided by access point <NUM>. Other devices not shown in <FIG> may also be connected to a local area network provided by access point <NUM>. Such devices may include control devices, additional playback devices, and other types of network client devices.

As shown in <FIG>, system <NUM> also includes an access point <NUM> that facilitates a local area network. In some examples, access point <NUM> provides a first local area network in an infrastructure (station) mode in which client devices communicate with one another through the access point. Alternatively, access point <NUM> represents a node in a point-to-point mesh network. In such a network, one or more other nodes may be connected to the mesh network via the access point <NUM>. Other examples are possible as well.

In an example, playback device <NUM> accesses, from a file stored in data storage of playback device <NUM>, first network parameters. Such first network parameters may include any of the example network parameters described above, as well as any other suitable network parameters. For instance, the first network parameters may include network parameters for a first wireless local area network, such as a SSID, wireless channel, and an IP address for the playback device <NUM>. The first playback device may retrieve additional network parameters from the file as well.

Referring back to <FIG>, at block <NUM>, implementation <NUM> involves determining that the first playback device is unable to establish a valid network connection to the first local area network. For instance, the first playback device may determine whether the first playback device is able to establish a valid network connection to the first local area network in response to accessing the first network parameters from the file. As noted above, in some cases, the first network parameters will have become stale. In such circumstances, the first playback device determines that the first playback device is unable to establish a valid network connection to the first local area network.

Determining that the first playback device is unable to establish the valid network connection to the first local area network may involve attempting to connect to the first local area network using the first network parameters retrieved from the file in data storage. To reduce the likelihood of a false-positive determination, the first playback device may repeatedly attempt to connect to the first local area network. A threshold number of failed attempts may cause the first playback device to determine that the first playback device is unable to establish a valid network connection. In some implementations, the first playback device may make repeated attempts to connect over a significant window of time (e.g., a window that is longer than <NUM> seconds, such as a <NUM>-<NUM> second window, among other examples). Repeated attempts to connect over such a window of time reduce the likelihood of a false-positive determination that the first playback device is unable to establish a valid network connection.

The first playback device may determine that it has established a "valid" network connection under any of a number of different conditions. For instance, the first playback device may determine whether it has established a network connection in station mode to an access point of the first local area network. The first playback device may also determine whether it has established a network path to a wired network connection through a point-to-point mesh network using an IP address assigned by an access point (i.e., not a default or auto-assigned IP address, which might not be indicative of a valid network connection). The first playback device may further determine whether it has established a network connection to a control device. A first playback device may establish a point-to-point network connection with a control device as part of a set-up procedure. In making such a connection, the playback device may utilize a default or auto-assigned IP address. If the first playback device is unable to establish a network connection under any of these conditions, then the first playback device may determine that it is unable to establish a "valid" network connection.

Referring back to <FIG>, in the example noted above, playback device <NUM> may determine whether playback device <NUM> is able to establish a network connection to the first wireless local area network using the first network parameters retrieved from a file stored in data storage of playback device <NUM>. For instance, playback device <NUM> may attempt to connect to establish a valid network connection with access point <NUM>. If playback device <NUM> is unable to establish a network connection (perhaps after repeated attempts over a window of time), then playback device <NUM> may determine that it is unable to establish a network connection to the first wireless local area network using the first network parameters.

In <FIG>, at block <NUM>, implementation <NUM> involves broadcasting a probe request message. For example, the first playback device may broadcast a probe request message over multiple wireless channels via a network interface (e.g., an IEEE <NUM> compatible wireless network interface). In some implementations, the first playback device broadcasts the probe request message in response to determining that the first playback device is unable to establish the valid network connection to the first local area network.

The first playback device broadcasts a probe request message in an attempt to reach one or more second playback devices of the same media playback system as the first playback devices. Such second playback devices may be configured (e.g., programmed) to listen for probe request messages via respective network interfaces, and in response to receiving a probe request message, send a response to the sender (i.e., the first playback device). Ultimately, the response may include second network parameters in use by a second playback device to establish a valid network connection to a particular local area network.

To increase the likelihood of the probe request message being received by one or more second playback devices, broadcasting the probe request message may involve broadcasting the probe request over multiple wireless channels. For instance, the first playback device may broadcast the probe request message over the allowed channels in one or more frequency bands (e.g., channels <NUM>-<NUM> in the <NUM> band). Allowed channels and bands may vary by country and/or jurisdiction.

The probe request message may include various indications that provide information about the first playback device to second playback devices that receive the probe request message. For instance, the probe request message may include an indication of the first playback device (e.g., an address of the first playback device). The probe request message may also include an indication that the first playback device is lost. Such an indication may take the form of a certain sequence of characters or a flag that can be set to indicate whether the broadcasting device is lost (e.g., a '<NUM>' if lost and a '<NUM>' if not lost). The probe request message may also include a destination address (i.e., a broadcast address, such as in an IPv4 network, the <NUM>. <NUM> address).

For instance, the probe request message may also include an indication of the media playback system to which the first playback system belongs. Example media playback systems described herein may each have an assigned household ID (HHID) that distinguishes a given media playback system (a "household") from other media playback systems. Other types of identifiers may distinguish playback devices within a media playback system, such as zone names, IP addresses, player IDs, or MAC addresses, among other examples. An example media playback system may include one or more playback devices, but the system is has a single HHID that identifies the system as a whole, whether it include one playback device or multiple playback devices. The probe request message may include an indication of a household ID (HHID) of the media playback system to which the first playback device belongs.

In some implementations, the probe request message may include (or consist of) a probe request frame. A probe request frame is a particular type of message defined in the <NUM> specification to scan an area for existing <NUM> networks. The probe request frame may include various information elements that provide information about the first playback device to second playback devices that receive the probe request message. Such information elements may include the various indications described above, such as an indication that the first playback device is lost and an indication of the media playback system to which the first playback system belongs, among others.

To illustrate, <FIG> depicts an example probe request frame 700A, which the first playback device may broadcast in response to determining that it is unable to establish a valid connection. Probe request frame 700A may conform to a specification, such as the IEEE <NUM> specification. While probe request frame 700A may conform to a specification, probe request frame 700A may also be modified for certain implementations. For instance, example probe request frames may include additional fields, or the fields of an IEEE <NUM> probe request frame may be re-purposed for this implementation.

As shown, within the MAC header, probe request frame 700A includes a frame control 702A, which may indicate the type of frame. Probe request frame 700A also includes a duration 704A, which for broadcast or multicast frames is set to <NUM>. Probe request frame 700A further includes a destination address (DA) 706A and source address (SA) 708A, which indicate the destination (e.g., the all 'f's broadcast address) and the source (e.g., the first playback device) of the probe request frame 700A, respectively. Probe request frame 700A further includes a basic service set (BSS) ID 710A. In the probe request message, the BSS ID may be set to the broadcast BSS ID (e.g., the all <NUM>-s BSSID). Frames that use the broadcast BSSID pass through any BSSID filtering, which allows probe request messages to reach any BSS in wireless range.

Within the frame body, probe request frame 700A also includes a service set ID (SSID) 712A and supported rates 714A. Stations (e.g., second playback devices) that receive probe requests use this information to determine whether the transmitting device (e.g., the first playback device) can join the network. The SSID 712A may be set to the SSID of a specific network or set to join any compatible network. This field may be set to the HHID of the media playback system to which the first playback device belongs. If the first playback device is able to join multiple media playback systems, this field may include a list of HHIDs. In some implementations, the SSID of a wireless network of interconnecting devices of a media playback system may also serve as the HHID of the media playback system. Alternatively, this can be set to the broadcast SSID, which indicates that the first playback device is allowed to join any network. The probe request frame 700A also includes rates 714A, which indicates the rates supported by the first playback device. The probe request frame 700A further includes frame check sequence (FCS) 716A, which is an error-detecting code added to the frame.

Referring back to <FIG>, in the example introduced above, playback device <NUM> may broadcast a probe request message in response to determining that it is unable to establish a valid network connection using the first network parameters retrieved from the file in data storage. The broadcasted probe request message may indicate that playback device <NUM> belongs to a particular media playback system (e.g., a media playback system also including playback device <NUM> and/or <NUM> and having a specific HHID). The broadcasted probe request message may further indicate that playback device <NUM> is lost. Other indications are possible as well, as noted above.

Referring again to <FIG>, at block <NUM>, implementation <NUM> involves receiving a response to the probe request message. For example, the first playback device may receive a response to the probe request message via the network interface from a second playback device. The response to the probe request message indicates second network parameters.

Such second network parameters are network settings in use by the second playback device to establish a valid network connection to a particular local area network. In some cases, this local area network may be the first local area network to which the first playback device was previously connected using the first network parameters stored in the file. However, certain of the parameters may have changed (e.g., the wireless channel) which caused the first network parameters to become stale. Alternatively, the second network parameters may indicate network settings in use by the second playback device to connect to a second local area network. For instance, the first playback device may have been moved between two households (e.g., between a user's primary residence and vacation home). The two households may be associated with different HHIDs. The first and second local area networks may be networks at the primary residence and vacation home, respectively (or vice versa).

As indicated above, a second playback device that receives the probe request message may send a response to the received probe request message if certain conditions are met. A first condition may be that the second playback device is part of the same media playback system (household) as the first playback device. As noted above, the first playback device may indicate its household in the probe request message. Another condition may be that the second playback device has a valid network connection. In response to receiving the probe request message, a second playback device may determine whether it meets the appropriate conditions, and if so, transmit a response message to the probe request message.

In some cases, multiple second playback devices may receive the probe request message and determine that the appropriate conditions for response are met. As such, in some cases, the first playback device may receive multiple response messages. A second playback device in the household of the first playback device which does not have a valid network connection will either not respond to the probe request message or send a response without second network parameters, among various implementations. The second playback device(s) may send such response(s) to the source address indicated in the probe request message (e.g., the address indicated in the SA 708A field).

To illustrate, <FIG> depicts an example probe response frame 700A, which a second playback device may transmit in response to receiving a probe request message (and perhaps also in response to determining that one or more conditions are met). Probe response frame 700B may conform to a specification, such as the IEEE <NUM> specification. While probe response frame 700B may conform to a specification, probe response frame 700B may also be modified for certain implementations. For instance, example probe response frames may include additional fields, or the fields of an IEEE <NUM> probe response frame may be re-purposed for this implementation.

As shown, within the MAC header, probe response frame 700B includes a frame control 702B and a duration 704B. Probe response frame 700B further includes a destination address (DA) 706B and source address (SA) 708B, which indicate the destination (e.g., the first playback device) and the source (e.g., the second playback device) of the probe response frame 700B, respectively. Probe response frame 700B further includes a basic service set (BSS) ID 710B. The BSS ID 710B may be set to the BSS of the particular local area network to which the second playback device is currently connected.

Within the frame body, probe request frame 700B includes parameters 712B. Parameters 712B may indicate the second network parameters of the local area network to which the second playback device has a valid connection. The first playback device may ultimately establish a valid connection by matching parameters 712B. Parameters 712B may include a time stamp (for synchronization), a beacon interval, capability info, and a SSID, among other examples.

Referring back to <FIG>, in the example introduced above, playback device <NUM> may receive a response message from one or more of playback device <NUM> and playback device <NUM>. For instance, if playback device <NUM> receive a probe request message from playback device <NUM> and determines that it is part of the same household as playback device <NUM> and has a valid network connection, then playback device <NUM> may responsively send a response message to playback device <NUM>. The response message from playback device <NUM> may indicate second network parameters that playback device <NUM> is using to connect to the network (e.g., the WLAN created by access point <NUM>).

Referring again to <FIG>, at block <NUM>, implementation <NUM> involves establishing a valid network connection to a particular network. For example, the first playback device may establish, via the wireless network interface, a valid network connection using the second network parameters in the response message received from the second playback device. The first playback device establishes the valid network connection to the same particular local area network as the first playback device. The particular local area network may be the first local area network that the first playback device previously was connected to using the first network parameters or a second local area network to which the second playback device is now connected. In some implementations, the first playback device attempts to establish the connection using the second network parameters in response to receiving the response message.

The first playback device may establish a valid network connection to a number of different types of networks. In some instances, the network connection is a network connection in station mode to an access point of the particular local area network. Alternatively, the network connection is a wireless network path to a wired network connection using an IP address assigned by an access point. Such a connection may be established when the particular local area network is a mesh point-to-point network between multiple playback devices of the media playback system. Other examples are possible as well.

Referring back to <FIG>, in the example discussed previously, playback device <NUM> establishes a valid connection to the network using the second network parameters received from playback device <NUM>. For instance, playback device <NUM> may establish a valid connection to the WLAN created by access point <NUM>. Other examples are possible as well. For instance, playback device may establish a valid connection to a point-to-point mesh network, perhaps by connecting to playback device <NUM> (or playback device <NUM>).

Referring again to <FIG>, at block <NUM>, implementation <NUM> involves joining the media playback system. For example, the first playback device may join a media playback system that comprises the second playback device. By joining the media playback system, the first playback device may be controllable by control devices of the media playback system. Further, the first playback device may share state information (e.g., one or more state variables) with other playback devices of the media playback system and/or the control devices of the media playback system.

Further, joining the media playback system configures the first playback device to play back audio content using the established valid network connection to the particular local area network. For instance, the first playback device may retrieve audio content from one or more audio sources registered with the media playback system using the network connection. In addition, the first playback device may play back media content in synchrony with one or more second playback devices of the media playback system using the network connection. For example, the first playback device may receive audio content and/or playback timing information using the network connection.

Returning again to the example of <FIG>, after establishing the network connection, playback device <NUM> may join the media playback system that includes playback device <NUM> (and possibly playback device <NUM>). Playback device <NUM> may then share state information and perform joint operations, such as playback, with these playback devices. Further, any control devices connected to the playback system may now control playback device <NUM> over the established network connection.

As discussed herein, in example media playback systems, network parameters may be stored in respective files in data storage of each playback device of a media playback system. In some implementations, each file may have a version number also stored in the file. The version number may reflect a version of the network parameters stored in the file. Versioning the network parameters may facilitate use of the most-recent network parameters available in a media playback system.

For instance, after receiving network parameters, a playback device may compare a version number of the received network parameters with a version number of the network parameters stored in data storage. If the version number of the received network parameters is newer, the playback device may update (e.g., replace) the network parameters stored in the file with the received network parameters. For instance, after receiving the response message with the second network parameters in block <NUM>, the first playback device may compare a version number of the second network parameters with a version number of the first network parameters. If the version number of the second network parameters is newer, then the first playback device may replace or otherwise update the file stored in data storage with the second network parameters. A version number may be newer when the version number is the greater number and/or if the version number is associated with a more recent timestamp. Upon replacing the network parameters in the file, the first playback device may use those network parameters in establishing a network connection (e.g., as described in block <NUM>).

Moreover, a playback device replicates the network parameters among other playback devices. For instance, a first playback device of a media playback system may determine the most recent network parameters of the media playback system. Such determining may involve receiving, via a network interface from multiple playback devices of the media playback system, messages indicating respective network parameters stored in files of respective data storages of multiple second playback devices. In some implementations, the first playback device receives such message in response to requesting network parameters from the second playback devices. Such messages may take the form of probe request and probe response frames, among other examples.

After receiving messages indicating the respective network parameters stored in files of respective data storages of the second playback devices, the first playback device may determine, based on respective version numbers of the network parameters indicated in each of the received messages, that particular network parameters having the latest version number or associated with a more recent timestamp are the most recent network parameters of the media playback system. For instance, the playback device may compare version numbers of network parameters in its network settings files against version numbers of received network parameters. In response to determining the most recent network parameters of the media playback system, the first playback device may update the network parameters in its stored file (if such network parameters are different). The first playback device may then establish a valid network connection using the updated network parameters.

Further, if one or more second playback devices sent lower-versioned network parameters, the first playback device may cause those playback devices to update their respective network parameters. For instance, the first playback device may update, via the network interface, at least one file stored in data storage of a second playback device with the most-recent network parameters. Such updating of the network parameters causes the second playback device to establish a valid network connection to the particular WLAN using the most-recent network parameters.

As indicated above, some example techniques may involve multiple playback devices. <FIG> shows example system <NUM> that includes playback device <NUM>, playback device <NUM>, and playback device <NUM>. Under example techniques described herein (e.g., implementation <NUM>), one or more of playback device <NUM>, playback device <NUM>, and playback device <NUM> may re-establish network connectivity using network parameters from another of playback device <NUM>, playback device <NUM>, or playback device <NUM>.

As shown in <FIG>, system <NUM> also includes an access point <NUM> that facilitates a local area network. Via an Ethernet (IEEE <NUM>) or other wired network interface, playback device <NUM> is connected to access point <NUM>. In addition, via a wireless (IEEE <NUM>) network interface, playback device <NUM> forms the root of a point-to-point mesh network. Playback device <NUM> is configured to connect to access point <NUM> via a wireless point-to-point connection to playback device <NUM>. Likewise, playback device <NUM> is configured to connect to access point <NUM> via a wireless point-to-point connection to playback device <NUM> (which is in turn configured to connect to playback device <NUM>, as noted above).

The network parameters reflecting these network configurations of each playback device are stored in respective files in data storage of each playback device. In an example, while playback device <NUM> is powered off or otherwise unavailable, the wireless channel of playback devices <NUM> and <NUM> is updated from to a different channel (e.g., from channel <NUM> to channel <NUM>). As a result, the network parameters in the file in data storage of playback device <NUM> indicate a different channel, and, as a result, playback device <NUM> attempts to establish the point-to-point connection to playback <NUM> on channel <NUM>, while playback device <NUM> attempts to establish the point-to-point connection to playback <NUM> on channel <NUM>. Because of this difference in wireless channel, playback device <NUM> and playback device <NUM> are unable to establish a network connection.

As described above in connection with implementation <NUM>, in operation, an example playback device determines whether it is able to establish a valid connection (e.g., after retrieving network parameters from a file in data storage, perhaps after booting). In the example above, playback device <NUM> and playback device <NUM> may each determine whether they are able to establish a valid network connection. Given the difference in wireless channel described above, playback device <NUM> and playback device <NUM> may each determine that they are unable to establish a valid network connection. Playback device <NUM> and playback device <NUM> may make this determination using any suitable technique, such as the example techniques described above in connection with block <NUM> of <FIG>.

Having determined that it is unable to establish a valid network connection, playback device <NUM> attempts to re-establish connectivity. In particular, playback device <NUM> broadcasts a probe request message (e.g., as described in block <NUM> of <FIG>). In response to the probe request message, playback device <NUM> may receive a response with network parameters from playback device <NUM> (e.g., a response message as described in block <NUM> of <FIG>). These network parameters indicate that playback device <NUM> is using channel <NUM>.

Similarly, having determined that it is unable to establish a valid network connection, playback device <NUM> attempts to re-establish connectivity. In particular, playback device <NUM> broadcasts a probe request message (e.g., as described in block <NUM> of <FIG>). However, unlike playback device <NUM>, playback device <NUM> is not in wireless range of playback device <NUM>. As such, playback device <NUM> does not receive a response from playback device <NUM> to the probe request message broadcasted by playback device <NUM>. Playback device <NUM> also does not receive a probe request message with network parameters from playback device <NUM>, as playback device <NUM> does not have a network connection (i.e., playback device <NUM> is lost).

On the other hand, having received a response with network parameters from playback device <NUM>, playback device <NUM> uses those network parameters in an attempt to re-establish connectivity. In particular, playback device <NUM> switches to channel <NUM>, which is the wireless channel represented in the response message from playback device <NUM> (and in use by playback device <NUM>). Playback device <NUM> then obtains an IP address and establishes a valid network connection to access point <NUM> via playback device <NUM>.

However, as noted above, playback device <NUM> and <NUM> were updated to wireless channel <NUM> after playback device <NUM> was set to channel <NUM>. As such, a version number of the network parameters stored in the file on playback device <NUM> is newer than a version number of the network parameters stored in the file on playback device <NUM>. Accordingly, when playback device <NUM> and playback device <NUM> establish a connection, playback device <NUM> may receive network parameters from playback device <NUM> and determine that these network parameters are more recent than its own stored network parameters. As a result, playback device <NUM> may update its own network parameters with the network parameters from playback device <NUM>. This causes playback device <NUM> to use wireless channel <NUM>.

When playback device <NUM> switches to wireless channel <NUM>, playback device <NUM> may lose its network connection to playback device <NUM>, as playback device <NUM> is now using wireless channel <NUM>. Having lost the network connection to playback device <NUM>, playback device <NUM> may repeatedly attempt to connect to playback device <NUM> over a window of time. If those attempts to connect fail, playback device <NUM> may again determine that it is unable to establish a valid network connection.

In response to determining that it is unable to establish a valid network connection, playback device <NUM> broadcasts another probe request message. In response to the probe request message, playback device <NUM> may receive a response with network parameters from playback device <NUM>. These network parameters indicate that playback device <NUM> is using channel <NUM>. Playback device <NUM> uses those network parameters in an attempt to re-establish connectivity. In particular, playback device <NUM> switches to channel <NUM>, which is the wireless channel represented in the response message from playback device <NUM>. Playback device <NUM> then obtains an IP address and re-establishes a valid network connection to access point <NUM> via playback device <NUM>.

Once playback device <NUM> is using channel <NUM>, playback device <NUM> may establish a network connection to playback device <NUM> (as playback device <NUM> is still on channel <NUM>). This allows playback device <NUM> to establish a valid network connection via playback device <NUM> (and playback device <NUM>) to access point <NUM>. At this point, playback devices <NUM>, <NUM>, and <NUM> all have established network connections using the most recent network parameters available in the media playback system.

If instead of channel <NUM>, the network parameters stored on playback device <NUM> directed playback device <NUM> to use channel <NUM>, then playback device <NUM> would have broadcasted another probe request message. Playback device <NUM> would have sent a response to the probe request message indicating that it was using channel <NUM>. Playback device <NUM> would then have switched to channel <NUM>.

Further, if the version number of the network parameters stored in playback device <NUM> were newer than the respective version numbers of network parameters stored in playback device <NUM> and <NUM>, these network parameters would be replicated to playback device <NUM> (and ultimately <NUM>) using the techniques described above.

As indicated above, some example techniques may involve a playback device re-establishing network connectivity. Since example playback devices stored their network settings in respective files in data storage, when an access point is replaced, playback devices that were wirelessly connected to the original access point will not immediately update their IP address. Instead, such playback devices may retain their network parameters until the next DHCP renew (which may be a lease that is days or weeks long). As a result, the playback devices that were wirelessly connected to the original access point will lose network connectivity. <FIG> presents an implementation <NUM>, not covered by the claimed invention, to facilitate re-establishing network connectivity when an access point (e.g., a wireless router) is replaced.

At block <NUM>, implementation <NUM> involves determining that a first access point has been replaced with a second access point. For instance, a playback device that is configured to connect to a first access point by way of a wireless network connection (e.g., via network parameters stored on the playback device) may determine that the first access point has been replaced with a second access point. In some cases, the first access point and the second access point are different physical devices that assign IP addresses in different subnets. For instance, the first access point assign IP addresses in the <NUM>. y subnet while the second access point assigns IP addresses in the <NUM>. Alternatively, the first access point and the second access point are the same physical device that has been reconfigured to lease IP addresses in a different subnet.

To illustrate, <FIG> shows example system <NUM> that includes playback device <NUM>, playback device <NUM>, playback device <NUM>, and playback device <NUM>. As shown in <FIG>, system <NUM> also includes an access point <NUM> that facilitates a local area network. Via an Ethernet (IEEE <NUM>) or other wired network interface, playback device <NUM> is connected to access point <NUM>. In addition, via a wireless (IEEE <NUM>) network interface, playback device <NUM> forms the root of a point-to-point mesh network. Playback device <NUM> is configured to connect to access point <NUM> via a wireless point-to-point connection to playback device <NUM>. Likewise, playback device <NUM> is configured to connect to access point <NUM> via a wireless point-to-point connection to playback device <NUM> (which is in turn configured to connect to playback device <NUM>, as noted above). Playback device <NUM> is also configured to connect to access point <NUM> via a wireless point-to-point connection to playback device <NUM>. A network device (e.g., a set-top box, smart television, or any other network device) is connected to playback device <NUM> via a wired Ethernet connection. This allows network device <NUM> to obtain a connection to access point <NUM> (via playback device <NUM> and <NUM>).

However, when access point <NUM> is updated to assign IP addresses in a different subnet (or replaced with a new access point that assigns IP addresses in a second subnet), then playback device <NUM> receives an IP address in this second subnet by way of its wired Ethernet connection to access point <NUM>. However, since playback device <NUM>, playback device <NUM>, and playback device <NUM> are configured to use IP addresses in the original (first) subnet, these playback devices lose their network connection to playback device <NUM>. Further, these playback devices might not obtain an IP address in the second subnet immediately (e.g., until their DHCP leases expire, which might be a significant period of time, such as <NUM> hours or more). During this time, playback device <NUM>, playback device <NUM>, and playback device <NUM> would be lost.

Further, because of its wired connection to network device <NUM>, playback device <NUM> may broadcast that it has a wired connection. In response, playback device <NUM> and playback device <NUM> may attempt to establish a valid network connection by connecting to playback device <NUM> via respective mesh point-to-point connections. However, because network device <NUM> is not an access point, such connections would not allow playback device <NUM> and playback device <NUM> (or playback device <NUM>) to establish a valid network connection.

Re-establishing network connectivity when access point <NUM> is replaced may involve one or more of playback device <NUM>, playback device <NUM>, and playback device <NUM> determining that access point <NUM> has been replaced or re-configured to assign IP addresses in a different subnet. After recognizing this condition, one or more of playback device <NUM>, playback device <NUM>, and playback device <NUM> may ultimately connect to the new IP, obtain an IP address in the new subnet, and re-establish a valid network connection.

Determining that the first access point has been replaced with a second playback device may involve monitoring DHCP frames. DHCP clients (e.g., playback devices) may initiate a DHCP connection by broadcasting a DHCP discovery message. When a DHCP server (e.g., an access point) receives a DHCP discover message (which is, in effect, an IP address lease request), the server reserves an IP address for the client and makes a lease offer by sending a DHCP offer message to the client. The client responds to the DHCP offer message by broadcasting a DHCP request, which requests the offered address.

In example implementations, an example playback device may monitor, within DHCP request frames received via a network interface (e.g., via a wireless network interface), for particular DHCP request frames that have a portion of the DHCP request frame set to a DHCP server ID. DHCP request frames are broadcasted, which allows the playback device to receive them. Moreover, DHCP request frames include a field containing the DHCP server ID (e.g., an IP address of the DHCP server). Upon receiving a DHCP request frame, the playback device may determine whether the DHCP server ID is set, and whether the DHCP server ID in the received DHCP request frame is different from the DHCP server ID stored in the file on data storage. If the DHCP server ID in the received DHCP request frame is different from the DHCP server ID stored in the file on data storage, the playback device may determine that the DHCP server (i.e., the access point) has changed (i.e., been replaced or reconfigured).

Referring back to <FIG>, at block <NUM>, implementation <NUM> involves connecting to the second access point. For instance, the playback device may attempt to connect to the second access point in response to determining that the first access point has been replaced with the second access point. Attempting to connect to the second access point may involve the playback device broadcasting a DHCP discovery message. As noted above, broadcasting such a DHCP discovery message initiates the DHCP connection process, which ultimately leads to the playback device obtaining a new IP address.

For instance, referring back to <FIG>, in response to determining that access point <NUM> has been replaced (or reconfigured), one or more of playback device <NUM>, playback device <NUM>, and/or playback device <NUM> may attempt to connect to the new access point. For instance, playback device <NUM> may broadcast a DHCP discovery message, which may be received by the new access point. The new access point may then continue with the DHCP connection process.

In <FIG>, at block <NUM>, implementation <NUM> involves requesting an IP address in the second subnet. For instance, the playback device may broadcast a DHCP request message in response to receiving a DHCP offer message from the second access point. The DHCP offer message contains fields indicating the client's MAC address, the offered IP address, the subnet mask, the lease duration, and the IP address of the DHCP server making the offer.

For instance, referring again to <FIG>, one or more of playback device <NUM>, playback device <NUM>, and/or playback device <NUM> request an IP address in the subnet of the local area network provided by the second access point. For instance, playback device <NUM> may broadcast a DHCP request message, which may be received by the new access point. The new access point may then continue with the DHCP connection process.

In some cases, multiple DHCP servers may be on the same subnet. To identify this condition, the playback device may determine that an estimated network of the playback device as provided by the second access point is different than a current network of the playback device as provided by the first access point. For instance, to determine the current network of the playback device, the playback device may perform an AND operation between the current IP address of the playback device and the subnet mask, which are both stored in the network settings file in data storage. Then, to determine the estimated network of the playback device, the playback device may perform an AND operation between the current new IP address of the playback device (i.e., the IP address in the second subnet) and the subnet mask. The playback device may then compare the estimated network of the third playback device to the current network of the third playback device to determine whether there are two DHCP servers on the same subnet. If so, the playback device may renew its IP address or take other action to connect to the desired DHCP server.

Referring again to <FIG>, at block <NUM>, implementation <NUM> involves establishing a network connection to the second access point. For instance, the playback device may receive a DHCP acknowledgment from the DHCP server. The DHCP acknowledgment includes further configuration information for the playback device to use to configure its network interface for communication on the local area network provided by the DHCP server.

For instance, referring back to <FIG>, in response to determining that access point <NUM> has been replaced (or reconfigured), one or more of playback device <NUM>, playback device <NUM>, and/or playback device <NUM> may attempt to establish a network connection to the new access point. For instance, playback device <NUM> may receive a DHCP acknowledgement from the DHCP server and configure its network interface to use the network parameters indicate in the received message(s). Playback device <NUM> may store these network parameters in the network settings file in data storage.

The specification is presented largely in terms of illustrative environments, systems, procedures, steps, logic blocks, processing, and other symbolic representations that directly or indirectly resemble the operations of data processing devices coupled to networks. These process descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Numerous specific details are set forth to provide a thorough understanding of the present disclosure. However, it is understood to those skilled in the art that certain embodiments of the present disclosure can be practiced without certain, specific details. In other instances, well known methods, procedures, components, and circuitry have not been described in detail to avoid unnecessarily obscuring aspects of the embodiments. Accordingly, the scope of the present disclosure is defined by the appended claims rather than the forgoing description of embodiments.

Claim 1:
A method for a first playback device (<NUM>-<NUM>, <NUM>, <NUM>-<NUM>) of a media playback system (<NUM>), the method comprising:
accessing, by the first playback device, from a file stored in data storage of the first playback device, first network parameters, wherein the first playback device previously established a valid network connection to a first local area network using the first network parameters;
determining, by the first playback device, that the first playback device is unable to establish a valid network connection to the first local area network using the first network parameters;
receiving, from one or more second playback devices (<NUM>-<NUM>, <NUM>, <NUM>-<NUM>) via a network interface (<NUM>) of the first playback device, one or more messages indicating second network parameters, wherein the second network parameters are used by the one or more second playback devices to establish a valid network connection to a second local area network;
establishing, by the first playback device, a valid network connection to the second local area network using the second network parameters; and
replicating the second network parameters among other playback devices of the media playback system.