Patent Publication Number: US-9894631-B2

Title: Authentication using DHCP services in mesh networks

Description:
CROSS REFERENCE TO RELATED MATTERS 
     This application is a continuation of U.S. patent application Ser. No. 14/296,765 filed on Jun. 5, 2014, which claims priority to U.S. application Ser. No. 13/481,617, now issued U.S. Pat. No. 8,755,385, filed on May 25, 2012, which claims priority to PCT International Application No. PCT/US12/36832, filed on May 7, 2012, and European Patent Application No. 12166694.5, filed May 3, 2012, all of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     With the advent of smart device technology, increasing number of smart devices have been deployed for residential, commercial and military uses nowadays. Examples of these devices include smart utility meters, sensors, control devices, routers, regulators, etc. Generally, when a new device is deployed, a technician will go to a field where the new device will be deployed and manually set up the new device in the field. The technician may, for example, configure and authenticate the new device with a network. The technician may then register the new device with the network and possibly a central server that maintains information of each device in the network. 
     The standard way of registration and joining a wireless network places a heavy load on the wireless network and may lead to congestion on an already heavily loaded network. The standard approach of joining a wireless network consists of three steps: first a joining node must complete 802.1x authentication, then the node communicates with a Dynamic Host Configuration Protocol (DHCP) server to acquire an internet protocol (IP) address, and finally the node contacts a network management server (NMS) to obtain required configuration information. These three steps demand heavy end-to-end packet exchange, which provides a considerable load for challenged wireless communication networks. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items. 
         FIG. 1  illustrates an example environment usable to implement registration and/or migration of a device in a network. 
         FIG. 2  illustrates the example device of  FIG. 1  in more detail. 
         FIG. 3  illustrates an example method of device registration in a network. 
         FIG. 4  illustrates an example method of determining whether to allow or reject a request of a device to join a network. 
         FIG. 5  illustrates an example method of device migration from one network to another. 
     
    
    
     DETAILED DESCRIPTION 
     Overview 
     As noted above, existing deployment of a new device generally requires a technician to manually configure and authenticate the new device with a network in the field, and connect the new device to the network. This connection and authentication process can be cumbersome and time consuming. The situation becomes more complicated when the network is at or near its capacity (e.g., has limited or no bandwidth remaining to support the new device). In that instance, the technician may attempt to connect the new device to another available network if any exist. These situations not only pose difficulties in deploying new devices and migrating nodes from one network to another, but also create problems in synchronizing different devices within and across networks. 
     This disclosure describes methods of automated device registration and device migration in an autonomous routing network. The methods allow for automatic registration of a new device to a network through a minimal number of exchanges between the new device and the network. Furthermore, the methods allow migration or handover of a device from a network to another network due to a condition of the network and/or a condition of the new device that is to be deployed in the network. 
     Generally, a device may request to join a network. In some implementations, the requesting device may or may not know which device associated with the network is responsible for addressing or controlling an admission of a new device to join the network. In some implementations, the requesting device may broadcast a request to join the network, which may be heard by neighboring devices (i.e., devices that are within transmission range of the requesting device). Additionally or alternatively, the requesting device may discover neighboring devices in the network by overhearing transmissions from the neighboring devices. The requesting device may then send the request directly to the neighboring devices through a message or beacon, for example. 
     In response to receiving the request, the neighboring device may parse the request and know that the requesting device requests to join the network. In one implementation, the neighboring device may relay the request of the requesting device to a controlling device that is responsible for addressing or controlling an admission of a new device to join the network. Alternatively, the neighboring device may relay the request to a device in the network that is a parent of the neighboring device, directing the parent device to relay the request to the controlling device, or another device that is hierarchically closer to the controlling device than the parent device. In one implementation, the neighboring device may relay the request to its parent device if, for example, the neighboring device does not know which device is responsible for addressing or controlling an admission of a new device to join the network. 
     Regardless of whether the request is relayed to the controlling device or the parent device, the neighboring device may insert a destination address (e.g., an IP address of the controlling device or the parent device) in the request, indicating a destination to which the request is directed. 
     In response to receiving the request, the controlling device associated with the network may determine whether to allow or reject the request of the requesting device to join the network. In one implementation, the controlling device may determine whether to allow or reject the request of the requesting device based on a condition of the requesting device. By way of example and not limitation, the controlling device may determine whether the requesting device is an isolated device based on information included in the received request. In one implementation, the requesting device may be determined to be isolated if the requesting device is incapable of joining networks other than the network of the controlling device. Additionally or alternatively, the requesting device may be determined to be isolated if the requesting device detects no other networks that cover the area in which the requesting device is situated. Additionally or alternatively, the requesting device may be determined to be isolated if the requesting device attempts or is forced to migrate from another network to the network of the controlling device, and this other network and the network of the controlling device are the only networks covering the area in which the requesting device is situated. Additionally or alternatively, the requesting device may be determined to be isolated if the requesting device has unsuccessfully exhausted (i.e., has been unable to join) all detected networks in its area except the network of the controlling device. Additionally or alternatively, the requesting device may be determined to be isolated if the network of the controlling device is the only network that can provide connectivity between the requesting device and servers such as Authentication, Authorization and/or Accounting (AAA) servers associated with the network. 
     Additionally or alternatively, the controlling device may determine whether to allow or reject the request of the requesting device to join the network based on a condition of the network. For example, the controlling device may determine whether a load on the network, such as a current number of devices, a current traffic, a current or average packet drop rate, a current or average bandwidth usage, etc., in the network is greater than or equal to a predetermined threshold. Additionally or alternatively, the controlling device may store or retrieve load or network statistics (such as current or average packet drop rate, current or average bandwidth usage, etc.) about the network and determine whether the load or network statistics (e.g., the current bandwidth usage) is greater than or equal to a predetermined threshold. 
     Based on the determining, the controlling device may allow or reject the request of the requesting device. For example, in response to determining that the requesting device is an isolated device, the controlling device may allow the request of the requesting device to join the network. If the controlling device further determines that the load (or the statistics) on the network, e.g., the current bandwidth usage, is/are greater than or equal to respective threshold(s), the controlling device may force one or more devices in the network to leave the network or migrate from the network to another network. By way of example and not limitation, the controlling device may select one or more devices based on knowledge of which devices in the network are capable of migrating or joining another network, and may force or request the one or more devices to leave the network of the controlling device. In this way, the controlling device may reduce the load to a sufficient or predetermined level to allow the requesting isolated device to join the network. 
     In response to determining to allow the request of the requesting device to join the network (regardless of the condition of the network), the controlling device may further prepare information related to joining to the network for the requesting device. The information may include, but is not limited to, a group key associated with the network, configuration information for the requesting device to set up with the network and/or a new address (such as an IP address) assigned to the requesting device, etc. The controlling device may send the information to the requesting device via the neighboring device. 
     The described methods allow the requesting device that wants to join the network to perform a single handshake with the network to join the network. In some implementations, the neighboring device, which is located in a neighborhood of the requesting device and is one hop away from the requesting device, may relay the request to the controlling device on behalf of the requesting device, thus saving the requesting device from randomly or aimlessly sending the request to the network. The described methods further allow smooth migration of an existing device in the network to another network, thus avoiding the network from overloading, overcrowding or exhausting resources of the network. Furthermore, the controlling device may store or retrieve other statistics such as percentage of bandwidth usage, percentage of isolated devices among all devices, etc., that are associated with the network and send a warning or alert to an administrator if one or more of these other statistics reach respective predetermined threshold(s). This facilitates the administrator to decide whether to add new supporting hardware for improving the bandwidth of the network and/or to physically re-arrange or re-locate some of the devices in the network. 
     In the examples described herein, the controlling device receives the request, determines whether to allow or reject the request, determines whether or not to force one or more devices in the network to leave the network, and prepares information related to enabling the requesting device to join the network. However, in other implementations, one or more other devices or services may perform some or all of these functions. For example, the controlling device may send or broadcast information of the condition of the network to part or all of devices in the network regularly or as needed. The controlling device may indicate in the sent or broadcasted information that the network will not accept admission of new devices except isolated devices. Accordingly, in one implementation, a device (e.g., the neighboring device) or service may determine whether to allow or reject the request of the requesting device to join the network, while another device or service may determine whether to force one or more devices in the network to leave the network, and yet another device or service may prepare information related to enabling the requesting device to join the network. 
     The application describes multiple and varied implementations. The following section describes an example environment that is suitable for practicing various implementations. Next, the application describes example systems, devices, and processes for implementing device registration and device migration. 
     Exemplary Environment 
       FIG. 1  is a schematic diagram of an example architecture  100  usable to implement device registration and device migration. The architecture  100  includes a plurality of nodes or devices  102 - 1 ,  102 - 2 ,  102 - 3 ,  102 - 4 ,  102 - 5 , . . . ,  102 -N (collectively referred to as devices  102 ) communicatively coupled to each other via direct communication paths or “links.” In this example, N represents a number of devices arranged in an autonomous routing area (ARA), such as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), neighborhood area network (NAN), personal area network (PAN), or the like. While only one ARA is shown in  FIG. 1 , in practice, multiple ARAs may exist and may collectively define a larger network, such as an advanced metering infrastructure (AMI) network. At any given time, each individual device may be a member of a particular ARA. Over time, however, devices may migrate from one ARA to another geographically proximate or overlapping ARA based on a variety of factors, such as respective loads on the ARAs, interference, or the like. 
     As discussed above, the term “link” refers to a direct communication path between two devices (without passing through or being propagated by another device). The link may be over a wired or wireless communication path. Each link may represent a plurality of channels over which a device is able to transmit or receive data. Each of the plurality of channels may be defined by a frequency range which is the same or different for each of the plurality of channels. In some instances, the plurality of channels comprises radio frequency (RF) channels. The plurality of channels may comprise a control channel and multiple data channels. In some instances, the control channel is utilized for communicating one or more messages between devices to specify one of the data channels to be utilized to transfer data. Generally, transmissions on the control channel are shorter relative to transmissions on the data channels. 
     In one implementation, some or all of the devices  102  may be implemented as any of a variety of devices such as, for example, smart utility meters (e.g., electric, gas, and/or water meters), sensors (e.g., temperature sensors, weather stations, frequency sensors, etc.), control devices, transformers, routers, servers, relays (e.g., cellular relays), switches, valves, combinations of the foregoing, or any device couplable to a communication network and capable of sending and/or receiving data. 
     In some implementations, some or all of the devices  102  may additionally or alternatively be implemented as any of a variety of conventional computing devices including, for example, a notebook or portable computer, a handheld device, a netbook, an Internet appliance, a portable reading device, an electronic book reader device, a tablet or slate computer, a game console, a mobile device (e.g., a mobile phone, a personal digital assistant, a smart phone, etc.), a media player, etc. or a combination thereof. 
     In this example, the devices  102  may further be configured to communicate with a central office  104  via an edge device (e.g., the device  102 - 4 ) which serves as a connection point of the ARA to a backhaul network(s)  106 , such as the Internet. In one implementation, the edge device may include, but is not limited to, a cellular relay, a cellular router, an edge router, a DODAG (Destination Oriented Directed Acyclic Graph) root, a root device or node of the ARA network, etc. In this illustrated example, the device  102 - 1  serves as a cellular relay and/or forwarding device for other nodes in the ARA, e.g., relaying communications from the other devices  102 - 2 - 102 -N of the ARA to and from the central office  104  via the network(s)  106 . 
     In one implementation, some or all of the devices  102  may include a processing unit  108 . The processing unit  108  may include one or more processor(s)  110  communicatively coupled to memory  112 . The memory  112  may be configured to store one or more software and/or firmware modules, which are executable on the processor(s)  110  to implement various functions. While the modules are described herein as being software and/or firmware stored in memory and executable on a processor, in other implementations, any or all of the modules may be implemented in whole or in part by hardware (e.g., as an ASIC, a specialized processing unit, etc.) to execute the described functions. 
     The memory  112  may comprise computer-readable media and may take the form of volatile memory, such as random access memory (RAM) and/or non-volatile memory, such as read only memory (ROM) or flash RAM. Computer-readable media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storage of information such as computer-readable instructions, data structures, program modules, or other data for execution by one or more processors of a computing device. Examples of computer-readable media include, but are not limited to, phase change memory (PRAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device. As defined herein, computer-readable media does not include communication media, such as modulated data signals and carrier waves. 
     In one implementation, some or all of the devices  102  may additionally include a radio  114 . The radio  114  comprises a radio frequency (RF) transceiver configured to transmit and/or receive RF signals via one or more of a plurality of channels/frequencies. In some implementations, some or all of the devices  102  includes a single radio  114  configured to send and receive data on multiple different channels, such as the control channel and multiple data channels of each communication link. The radio  114  may further be configured to implement a plurality of different modulation techniques, data rates, protocols, signal strengths, and/or power levels. The architecture  100  may represent a heterogeneous network of devices, in that the devices  102  may include different types of devices (e.g., smart meters, cellular relays, sensors, etc.), different generations or models of devices, and/or devices that otherwise are capable of transmitting on different channels and using different modulation techniques, data rates, protocols, signal strengths, and/or power levels. 
     Additionally or alternatively, in some implementations, some or all of the devices  102  may include a network interface  116 , and/or an input/output interface  118 . The processing unit  108  may further be configured to receive and act on data from the network interface  116 , received from the input/output interface  118 , and/or stored in the memory  112 . 
     The network(s)  106 , meanwhile, represents a backhaul network, which may itself comprise a wireless or a wired network, or a combination thereof. The network(s)  106  may be a collection of individual networks interconnected with each other and functioning as a single large network (e.g., the Internet or an intranet). Further, the individual networks may be wireless or wired networks, or a combination thereof. 
     The central office  104  may be implemented by one or more computing devices, such as servers, personal computers, laptop computers, routers, switches, etc. The one or more computing devices may be equipped with one or more processor(s) communicatively coupled to memory. In some examples, the central office  104  includes a centralized meter data management system that performs processing, analysis, storage, and/or management of data received from one or more of the devices  102 . For instance, the central office  104  may process, analyze, store, and/or manage data obtained from a smart utility meter, sensor, control device, router, regulator, server, relay, switch, valve, and/or other devices. The central office  104  may additionally or alternatively include a network management system (NMS) for maintaining a registry of devices of the AMI network, device configuration settings, version information, and the like. Although the example of  FIG. 1  illustrates the central office  104  in a single location, in some examples the central office may be distributed amongst multiple locations and/or may be eliminated entirely (e.g., in the case of a highly decentralized distributed computing platform). 
     In one implementation, the architecture may further include an authentication server  120  responsible for authenticating identities of the devices  102  in the ARA network. In some implementations, the architecture  100  may further include other servers  122 , which may control or support admission of new devices to the ARA network. In one implementation, the other servers  122  may include a security server responsible for maintaining and/or providing security services to the ARA network. 
     Example Device 
       FIG. 2  is a schematic diagram showing additional details of the device  102  (e.g., representative device  102 - 3 ) of  FIG. 1 . In this example, the radio  114  includes an antenna  200  coupled to an RF front end  202  and a baseband processor  204 . The RF front end  202  may provide transmitting and/or receiving functions. The RF front end  202  may include high-frequency analog and/or hardware components that provide functionality, such as tuning and/or attenuating signals provided by the antenna and obtained from one or more of the devices  102 . The RF front end  202  may provide a signal to the baseband processor  204 . 
     In one example, all or part of the baseband processor  204  may be configured as a software (SW) defined radio. In one example, the baseband processor  204  provides frequency and/or channel selection functionality to the radio  114 . For example, the SW defined radio may include mixers, filters, amplifiers, modulators and/or demodulators, detectors, etc., implemented in software executed by a processor or application specific integrated circuit (ASIC) or other embedded computing device(s). The SW defined radio may utilize processor(s)  110  and software defined or stored in memory  112 . Alternatively, the radio  114  may be implemented at least in part using analog components. 
     The processing unit  108  may further include a clock  206  configured to maintain a time. The clock  206  may further be configured to provide one or more count-up or count-down timers. Such timers may be used in frequency hopping among multiple communication channels. 
     A frequency hopping module  208  may be configured to communicate with the baseband processor  204  and the clock  206 . In one example, the frequency hopping module  208  is configured to obtain time information and/or set frequency-hopping timers in the clock  206 . Such time information and/or timers will indicate to the frequency hopping module  208  when to “hop” or tune a different channel or frequency. Additionally, the frequency hopping module  208  may be configured to direct the SW defined radio or other component of the radio  114  to perform the actual frequency changes. Accordingly, the frequency hopping module  208  is able to repeatedly shift between agreed upon frequencies, at agreed upon times and communicate with another device(s) for agreed upon periods of time and in agreed upon protocols. 
     In some implementations (e.g., when the device is a utility meter), the memory  112  may also include a metrology module  210  configured to collect consumption data of one or more resources (e.g., electricity, water, natural gas, etc.), which may then be transmitted to one or more other devices  102  for eventual propagation to the central office  104  or other destination. 
     The device  102  may additionally or alternatively include a discovery module  212 , a broadcasting module  214 , a sending module  216 , an encryption/decryption module  218 , a receiving module  220 , an analysis module  222 , a relay module  224 , a control module  226 , an authentication module  228 , and/or an address assignment module  230 , depending on a role or functionality of the device  102  in the ARA network. Details of the functions of these modules are described below. 
     Example Device Registration 
     In one implementation, prior to registering with the NMS in the central office  104  and/or becoming a member of the ARA network, a device  102  (e.g., the device  102 - 3 ) may attach to the ARA network first. By way of example and not limitation, the requesting device  102 - 3  may first attach to the ARA network to a point that the requesting device  102 - 3  may send a joining request to the ARA network, e.g., in an IP level or layer. For example, the requesting device  102 - 3  may first attach to the ARA network in MAC (i.e., Media Access Control) level or MAC layer. In one implementation, the requesting device  102 - 3  may correspond to a device, such as a smart utility meter, newly deployed to an area including the ARA network. Alternatively, the requesting device  102 - 3  may correspond to a device that is attempting to migrate to the ARA network from another ARA network as shown in  FIG. 1 . 
     In one implementation, the discovery module  212  of the requesting device  102 - 3  may actively or passively discover one or more neighboring devices  102  (e.g., the device  102 - 2 ) in a neighborhood thereof. A neighboring device of the requesting device  102 - 3  may include, for example, a device that is communicatively one hop away from the requesting device  102 - 3 . That is, a neighboring device is a device with which the requesting device can communicate directly via a communication link. In one implementation, the requesting device  102 - 3  may perform a neighbor discovery service in a MAC layer. Additionally or alternatively, the discovery module  212  may discover the one or more neighboring devices in the neighborhood thereof through examining signals detected or received at a predetermined frequency or frequency range designated for the ARA network that the requesting device  102 - 3  desires to join. 
     Additionally or alternatively, in some implementations, the requesting device  102 - 3  may broadcast the request to join the ARA network using the broadcasting module  214  with or without first knowing or discovering any device in the neighborhood thereof, in an attempt that one or more devices that are within the neighborhood thereof may receive the request, and may process the request on behalf of the requesting device  102 - 3 , and/or establish a connection with the requesting device  102 - 3 . 
     Additionally or alternatively, in one implementation, the broadcasting module  214  may broadcast a presence of the requesting device  102 - 3 , and wait for one or more devices in the ARA network that observe the presence of the requesting device  102 - 3  to communicate with the requesting device  102 - 3 . In one implementation, the broadcasting module  214  may broadcast the presence of the requesting device  102 - 3  using a predetermined code or message in a predetermined frequency or frequency range. 
     Regardless of whether the requesting device  102 - 3  discovers one or more neighboring devices  102  or the one or more neighboring devices  102  discover the requesting device  102 - 3 , the requesting device  102 - 3  may select a neighboring device  102  (e.g., the device  102 - 2 ), and send a request to join the ARA network associated with the neighboring device  102 - 2  to the neighboring device  102 - 2 . In one implementation, the requesting device  102 - 3  may send a Dynamic Host Configuration Protocol version 6 (DHCPv6) or DHCPv4 request to the neighboring device  102 - 2  through the sending module  216 . Alternatively, the requesting device  102 - 3  may include the join request in a beacon message and send the beacon message to the neighboring device  102 - 2  through the sending module  216 . 
     The requesting device  102 - 3  may or may not know an address (e.g., an Internet Protocol (IP) address) of a controlling device associated with the ARA network that is responsible for controlling an admission or addition of a new device to the ARA network. The controlling device in this example may comprise the edge device  102 - 4 , a DHCP server or another device outside the ARA. Specifically, the join request or the beacon message may or may not include a destination address of the controlling device associated with the ARA network to which the join request of the requesting device  102 - 3  needs to finally be directed. 
     In some implementations, the requesting device  102 - 3  may encrypt all or part of the join request or the beacon message by an encryption key using the encryption/decryption module  218 . The encryption key may comprise a private key or a symmetric key. In one implementation, each of the devices  102  (whether a device that is a member of the ARA network or a device that is allowable to join the ARA network) may share the same public/private key-pair or the same symmetric key during or after manufacture thereof. In some implementations, each of the devices  102  (whether a device that is a member of the ARA network or a device that is allowable to join the ARA network) may have an encryption/decryption key or symmetric key selected from a predetermined pool of encryption/decryption keys accessible by each of the devices  102 . In one implementation, each of the devices  102  (whether a device that is a member of the ARA network or a device that is allowable to join the ARA network) may have an encryption/decryption key or symmetric key that is known only to itself and one or more other devices and/or servers (such as the central office  104 , the authentication server  120 , and/or the controlling device of the ARA network, etc.). In other implementations, the requesting device  102 - 3  may send the join request or the beacon message without encryption, i.e., in a plain format. 
     Additionally or alternatively, in one implementation, the join request may include, but is not limited to, an identifier of the requesting device  102 - 3  and/or authentication information, such as an authentication signature, a nonce or an arbitrary value that is signed or encrypted using a predetermined key (e.g., the above encryption key, symmetric or public key) that has been registered in the requesting device  102 - 3  and known to the ARA network, the controlling device of the ARA network, the NMS in the central office  104  and/or the authentication server  120 . In some implementations, the join request may further include a message, a code, or other indicator that indicates whether the requesting device  102 - 3  is an isolated device. By way of example and not limitation, the requesting device  102 - 3  may be determined to be isolated if the requesting device  102 - 3  is incapable of joining networks (not shown) other than the ARA network. Additionally or alternatively, the requesting device  102 - 3  may be determined to be isolated if the requesting device  102 - 3  detects no other networks that cover an area in which the requesting device  102 - 3  is situated. Additionally or alternatively, the requesting device  102 - 3  may be determined to be isolated if the requesting device  102 - 3  attempts to migrate from another network (as shown in  FIG. 1 ) to the ARA network and this another network and the ARA network are the only networks covering the area in which the requesting device  102 - 3  is situated. Additionally or alternatively, the requesting device  102 - 3  may be determined to be isolated if the requesting device  102 - 3  has exhausted (i.e., has tried and failed to join) all detected networks in its area except the ARA network. Additionally or alternatively, the requesting device  102 - 3  (i.e., has failed to join) is isolated if the ARA network is the only network that is able to provide connectivity between the requesting device  102 - 3  and one or more servers such as NMS and DHCP servers, for example. 
     In some implementations, upon sending the join request to the neighboring device  102 - 2 , the requesting device  102 - 3  waits for a response from the ARA network via the neighboring device  102 - 2 . The response may indicate whether the join request of the requesting device  102 - 3  to join the ARA network is allowed or rejected. If the response indicates that the join request of the requesting device  102 - 3  is rejected or denied, the requesting device  102 - 3  may explore another ARA network and send a joining request to the other ARA network that the requesting device  102 - 3  may find. 
     In an event that the join request is allowed, the response may include, for example, a group key associated with the ARA network, configuration information for the requesting device  102 - 3  to join the ARA network, and/or an address (e.g., an Internet Protocol (IP) address) that is assigned to the requesting device  102 - 3 . Additionally or alternatively, in some implementations, the response may include address information of one or more devices  102  within the ARA network, including, for example, address information of devices along one or more paths designated by the controlling device for routing data packets from requesting device  102 - 3  within the ARA network, and/or address information of the controlling device associated with the ARA network. In one implementation, part or all of the response (e.g., the group key, etc.) may be encrypted using the symmetric key of the requesting device  102 - 3 . Additionally or alternatively, part or all of the response (such as the address information of the controlling device, for example) may be encrypted using the group key associated with the ARA network. 
     In some implementations, the requesting device  102 - 3  may only perform a single handshake or exchange (i.e., a single upstream message for the join request and a single downstream message for response to the join request), using the DHCPv6 or DHCPv4 protocol, for example, with the ARA network (e.g., the neighboring device  102 - 2  of the ARA network) to achieve joining to the ARA network. In one implementation, the requesting device  102 - 3  and/or the ARA network may achieve mutual authentication (i.e., authentication of an identity of the requesting device  102 - 3  by the ARA network or the authentication server  120 , and authentication of an identity of the ARA network by the requesting device  102 - 3 ) using this single handshake or exchange. 
     By way of example and not limitation, if the symmetric or asymmetric key (e.g., the public/private key) of the requesting device  102 - 3  is known (or is supposed to be known) only to the requesting device  102 - 3  and one or more other devices and/or servers (e.g., the authentication server  120 , the central office  104  and/or the controlling device) that are associated with the ARA network, the requesting device  102 - 3  and the ARA network may authenticate each other by using the symmetric or asymmetric key of the requesting device  102 - 3 . For example, the ARA network may authenticate an identity of the requesting device  102 - 3  if the authentication server  120 , for example, can successfully decrypt a nonce or a signature (which may be included in the join request) that has been encrypted using the symmetric or asymmetric key (e.g., the public key) of the requesting device  102 - 3 . Furthermore, the requesting device  102 - 3  may authenticate the ARA network if, for example, the requesting device  102 - 3  can successfully decrypt an encrypted group key (or other information such as the previously sent nonce or signature included in the response to the join request, for example) that has been encrypted using the symmetric or asymmetric key (e.g., the public key) of the requesting device  102 - 3 . In some implementations, if an encrypted group key is used as a source of authenticating the ARA network, the requesting device  102 - 3  may further determine an authenticity of the ARA network if the requesting device  102 - 3  can successfully communicate with other devices in the ARA network using the decrypted group key. In an alternative implementation, the requesting device  102 - 3  may perform a plurality of handshakes or exchanges with the ARA network, possibly using one or more protocols such as TCP/IP protocol and/or other Internet protocols, to achieve joining to the ARA network. 
     In one implementation, the neighboring device  102 - 2  may receive the join request sent or broadcasted from the requesting device  102 - 3  through the receiving module  220  of the neighboring device  102 - 2 . If the join request or the beacon message is encrypted, the neighboring device  102 - 2  may decrypt the join request or the beacon message using the encryption/decryption module  218  of the neighboring device  102 - 2 . The neighboring device  102 - 2  may parse the (decrypted or originally plain if unencrypted) join request and determine through the analysis module  222  that the requesting device  102 - 3  is requesting to join the ARA network. 
     In some implementations, in response to determining that the requesting device  102 - 3  requests to join the ARA network of the neighboring device  102 - 2 , the neighboring device  102 - 2  may relay the join request to the controlling device associated with the ARA network (e.g., the device  102 - 4 ). In one implementation, the neighboring device  102 - 2  may know an address (e.g., an IP address) of the controlling device and may relay the join request to the controlling device through the relay module  224 . By way of example and not limitation, the relay module  224  may include a relay agent, e.g., a DHCPv6 relay agent, to relay the (DHCPv6) join request sent from the requesting device  102 - 3  to the controlling device. For example, the relay module  224  of the neighboring device  102 - 2  may insert the IP address of the controlling device as a destination address of a data packet including the join request of the requesting device  102 - 3  and relay the data packet to the controlling device directly or indirectly through a parent device of the neighboring device  102 - 2 . 
     Alternatively, if the neighboring device  102 - 2  does not know the address of the controlling device, the relay module  224  of the neighboring device  102 - 2  may relay the data packet (which includes the request of the requesting device  102 - 3 ) to the parent device of the neighboring device  102 - 2  in the ARA network by, for example, inserting an IP address of the parent device, and directing or allowing the parent device of the neighboring device  102 - 2  to relay the join request of the requesting device  102 - 3  to the controlling device. 
     Additionally or alternatively, regardless of whether the join request is relayed to the controlling device or the parent device of the neighboring device  102 - 2 , the neighboring device  102 - 2  may further encrypt the relayed request using an encryption key of the neighboring device  102 - 2 . In one implementation, this encryption key may include a group key associated with the ARA network and distributed to each device  102  in the ARA network. In some implementations, this encryption key may include an encryption key selected from the pool of encryption/decryption keys accessible by each device  102  of the ARA network and/or assigned to the neighboring device  102 - 2 . In some other implementations, the neighboring device  102 - 2  may relay the request in a plain format, i.e., without encryption. In one implementation, the neighboring device  102 - 2  may use an address thereof as a source address of the request (or replace the source address of the join request of the requesting device  102 - 3  by the address of the neighboring device  102 - 2 ) that the neighboring device  102 - 2  is going to relay on behalf of the requesting device  102 - 3 . This allows proper forwarding of a reply from other devices or servers associated with the ARA network back to the requesting device  102 - 3 . For example, a response or reply (e.g., for the join request) to the requesting device  102 - 3  may use the address of the neighboring device  102 - 2  as the destination address, and request the neighboring device  102 - 2  to forward or relay the response or reply to the requesting device  102 - 3  accordingly. 
     In some implementations, the neighboring device  102 - 2  relays the join request of the requesting device  102 - 3  regardless of a condition of the ARA network and/or a condition of the requesting device  102 - 3 . Additionally or alternatively, in some implementations, the neighboring device  102 - 2  may receive an instruction from the controlling device  102 - 4 , indicating that the ARA network may not accept admission of a new device to the ARA network unless the new device to be added or joined to the ARA network is an isolated device. In this latter case, the analysis module  222  of the neighboring device  102 - 2  may further determine whether the requesting device  102 - 3  is an isolated device based on, for example, the join request received by the receiving module  220 . In response to determining that the requesting device  102 - 3  is not an isolated device, the neighboring device  102 - 2  may send a response or feedback to the requesting device  102 - 3  indicating that the request of joining to the ARA network is rejected because, for example, the neighboring device  102 - 2  has previously received from the controlling device  102 - 4  an instruction to reject admission of new devices except isolated devices. 
     In some implementations, in response to receiving the relayed request from the neighboring device  102 - 2 , the controlling device associated with the ARA network may determine whether to allow or reject the join request of the requesting device  102 - 3  based on a condition of the ARA network. The controlling device may determine whether to allow or reject the join request of the requesting device  102 - 3  using the control module  226 . In one implementation, the controlling device may play a role of admission control authority. In one implementation, the controlling device may comprise root or edge device (e.g., device  102 - 4 ) of the ARA network, a router of the ARA network, or may be distributed in one or more nodes of the ARA networks. In some implementations, the controlling device may alternatively be situated in a backend device such as the central office  104 , a root of a routing tree of one or more ARA networks manageable by the central office  104 , or another server  122  that may be affiliated with the central office  104 . In some implementations, the controlling device may include a DHCP or DHCPv6 server, which may be included in one or more of the other servers  122 . In one implementation, in an event that the controlling device does not include a DHCP or DHCPv6 server, or include one or more functions of the DHCP or DHCPv6 server, the controlling device may relay the join request to the DHCP or DHCPv6 server. In some implementations, the controlling device may include a combination of one or more devices including the DHCP or DHCPv6 server, a root device, an edge device, a router, a backend device such as the central office  104  or another server  122 . For ease of reference in this application, device  102 - 4  will be referred to as the controlling device. Device  102 - 4  is representative of a root node, edge router, or other edge device of the ARA network, which couples the ARA network to the central office  104  via the backhaul network  106 . 
     In some implementations, in response to receiving the relayed request from the neighboring device  102 - 2 , the controlling device  102 - 4  may determine whether to allow or reject the request of the requesting device  102 - 3  based on whether a load on the ARA network exceeds a predetermined threshold. By way of example and not limitation, the controlling device  102 - 4  may determine whether to allow or reject the request of the requesting device  102 - 3  based on whether the ARA network is overloaded (e.g., whether a current number of devices in the ARA network is greater than or equal to a predetermined threshold for accommodation). Additionally or alternatively, the controlling device  102 - 4  may determine whether to allow or reject the request of the requesting device  102 - 3  based on whether statistics (such as a current/average bandwidth usage, a current/average collision rate, a current/average drop rate of data packets, a current/average data traffic, etc.) of the ARA network is greater than or equal to a predetermined threshold for the statistics. 
     In one implementation, in response to determining that the load on the ARA network exceeds the predetermined threshold (e.g., the statistics is greater than or equal to the predetermined threshold for the statistics), the controlling device  102 - 4  may reject the (DHCP or DHCPv6) join request of the requesting device  102 - 3 . Alternatively, in some implementations, the controlling device  102 - 4  may further determine whether the requesting device  102 - 4  is an isolated device based on, for example, information in the received request. The information in the received request may include, for example, an indicator indicating that the requesting device  102 - 3  is an isolated device. In response to determining that the requesting device  102 - 3  is an isolated device, the controlling device  102 - 4  may allow the requesting device  102 - 3  to join the ARA network regardless of the condition of the ARA network (i.e., regardless of whether the load on the ARA network exceeds the predetermined threshold). 
     In some implementations, the controlling device  102 - 4  may further determine an authenticity of the requesting device  102 - 3  using the authentication module  228 . For example, the authentication module  228  of the controlling device  102 - 4  may determine an authenticity of the requesting device  102 - 3  based on the identifier of the requesting device  102 - 3  or the authentication signature included in the received request. Additionally or alternatively, the controlling device  102 - 4  may parse the request and send the identifier and/or the authentication signature of the requesting device  102 - 3  to an authentication server such as a security server or Authentication, Authorization and Accounting (AAA) server  120 . The security server or the AAA server  120  is responsible for authenticating identities of devices joining one or more ARA networks (including the current ARA network) that are managed by the central office  104 , for example. In one implementation, the security server or the AAA server  120  may be located outside the ARA network. In some implementations, the security server or the AAA server  120  may be another node or device (e.g., the device  102 - 1 ) within the same ARA network of the controlling device  102 - 4 . The controlling device  102 - 4  may send information including the identifier and/or the authentication signature of the requesting device  102 - 3  to the security server or the AAA server  120  using a networking protocol such as RADIUS (i.e., Remote Authentication Dial In User Service), for example. For ease of reference in this application, the AAA server is used as an example to describe operations of authenticating identities of devices joining one or more ARA networks. 
     In one implementation, upon successfully authenticating the identity of requesting device  102 - 3  based on the identifier and/or the authentication signature of the requesting device  102 - 3 , for example, the AAA server  120  may send a message to the controlling device  102 - 4  or the DHCP server associated or connected with the controlling device  102 - 4 , indicating that the identity of the requesting device  102 - 3  is successfully authenticated. Additionally or alternatively, in some implementations, the AAA server  120  may further send a group key (e.g., a group link-layer key) associated with the ARA network to the controlling device  102 - 4  or the DHCP server of the controlling device  102 - 4 . Additionally or alternatively, the AAA server  120  may send the message signed or encrypted by the group key (e.g., a group link-layer key) associated with the ARA network to the controlling device  102 - 4  or the DHCP server associated with the controlling device  102 - 4 . In one implementation, the controlling device  102 - 4  may have previously stored the group key associated with the ARA network, and may therefore decrypt the encrypted message using the group key. In one implementation, the controlling device  102 - 4  may not have information of the public or symmetric key of the requesting device  102 - 3 . In that instance, the AAA server  120  may encrypt the group key using a public or symmetric key of the requesting device  102 - 3 , and encrypt the message (including the encrypted group key) using the group key associated with the ARA network to the controlling device  102 - 4 , which may forward the group key that has been encrypted using the public or symmetric key of the requesting device  102 - 3  to the requesting device  102 - 3 . 
     In one implementation, if the controlling device  102 - 4  and the DHCP server are separate devices, the AAA server  120  may send the message to the DHCP server associated with the controlling device  120 - 4  (e.g., after the authentication request was sent from the DHCP server or from the controlling device  102 - 4  through the DHCP server). In response to receiving the message, the DHCP server may analyze the message and determine whether the identity of the requesting device  102 - 3  is authenticated. Additionally or alternatively, the DHCP server may relay the message to the controlling device  102 - 4 . In some implementations, the AAA server  120  may send the message to the controlling device  102 - 4  directly if the authentication request was sent from the controlling device  102 - 4  (or from the controlling device  102 - 4  through the DHCP server if the controlling device  102 - 4  and the DHCP server are separate devices). Regardless of whether the message is relayed from the DHCP server or directly sent from the AAA server  120 , in one implementation, in response to receiving the message from the AAA server  120 , the controlling device  102 - 4  may analyze the message and determine whether the identity of the requesting device  102 - 3  is authenticated. In response to determining that the identity of the requesting device  102 - 3  is authenticated, the controlling device  102 - 4  may send a message, which may or may not be encrypted using a public key or symmetric key of the requesting device  102 - 3  (which may depend on whether the controlling device  102 - 4  has the public or symmetric key of the requesting device  102 - 3 , for example) as described in foregoing implementations, to the requesting device  102 - 3  indicating that the identity of the requesting device  102 - 3  is authenticated and/or the requesting device  102 - 3  is allowed to join the ARA network. Additionally or alternatively, in some implementations, the controlling device  102 - 4  may encrypt the message using the group key associated with the ARA network, which may later be decrypted and parsed by the neighboring device  102 - 2  to the requesting device  102 - 3 . In one implementation, the message may further include, for example, a group key associated with the ARA network and other information that may or may not be encrypted using the public or symmetric key of the requesting device  102 - 3 , such as the encrypted group key received from the AAA server  120 , for example. In some implementations, in response to receiving the message, the requesting device  102 - 3  may decrypt the message if encrypted (for example using the public or symmetric key of the requesting device  102 - 3 ) and retrieve the group key associated with the ARA network. Additionally or alternatively, the requesting device  102 - 3  may decrypt the encrypted group key (such as the group key encrypted at the AAA server  120  using the public or symmetric key of the requesting device  102 - 3 ) to retrieve the group key. The requesting device  102 - 3  may then be allowed to send and/or receive data (for example, data encrypted using the group key, etc.) with other devices of the ARA network. 
     In some implementations, the controlling device  102 - 4  (or the DHCP server associated with the controlling device  102 - 4 ) may further send a registration request to the NMS using the sending module  216 . The registration request may include, for example, the identifier of the requesting device  102 - 3 , which may be signed or encrypted using a private key (of public/private keys) associated with the controlling device  102 - 4 , the group key associated with the ARA network, and/or the key associated with the requesting device  102 - 3 . In one implementation, the controlling device  102 - 4  may send the registration request to the NMS in a plain, unencrypted format. 
     Upon receiving the registration request from the controlling device  102 - 4 , the NMS may decrypt the message if the message is encrypted, parse the message and obtain the identifier of the requesting device  102 - 3 . In some implementations, the NMS may further retrieve information associated with requesting device  102 - 3  and/or information associated with the ARA network. In one implementation, the NMS may determine configuration information or parameters usable for the requesting device  102 - 3  to join or set up with the ARA network based on the retrieved information. The retrieved information may include, but is not limited to, a model type or device type of the requesting device  102 - 3 , a type of the ARA network the requesting device  102 - 3  is requesting to join, etc. Additionally or alternatively, the NMS may send the configuration information or parameters to the controlling device  102 - 4  or the DHCP server of the controlling device  102 - 4 . 
     In one implementation, in response to receiving the configuration information or parameters from the NMS, the address assignment module  230  of the controlling device  102 - 4  (or the DHCP server) may determine a new address (e.g., a new IP address such as IPv6 address) for the requesting device  102 - 3 . In one implementation, the controlling device  102 - 4  (or the DHCP server) may determine the new address based on a prefix assigned to a relay agent that the controlling device  102 - 4  (or the DHCP server) may employ, for example. Additionally or alternatively, the controlling device  102 - 4  (or the DHCP server) may determine the new address based on a prefix designated to or shared by devices in the ARA network of the controlling device  102 - 4 . In one implementation, the new address that is assigned to the requesting device  102 - 3  may include the prefix that is assigned to the relay agent of the controlling device  102 - 4  (or the DHCP server), or designated to or shared by each device in the ARA network. In some implementations, the controlling device  102 - 4  (or the DHCP server) may further generate a random number and use this random number for the rest of the new address. Additionally or alternatively, the controlling device  102 - 4  (or the DHCP server) may have previously reserved and stored a plurality of addresses (e.g., IPv6 addresses) to be used for devices adding to the ARA network. The controlling device  102 - 4  (or the DHCP server) may then randomly or sequentially select an address from the plurality of addresses for assigning to the requesting device  102 - 3 . 
     Additionally or alternatively, in some implementations, upon determining the new address to be assigned to the requesting device  102 - 3 , the controlling device  102 - 4  (or the DHCP server) may further check this new address with a DNS (i.e., Domain Name System) server to determine whether this new address is currently assigned to any other device. In one implementation, the controlling device  102 - 4  (or the DHCP server) may send the new address and the identifier of the requesting device  102 - 3  to the DNS server. If the controlling device  102 - 4  (or the DHCP server) receives a reply from the DNS server, indicating that the new address is currently assigned to another device, the controlling device may re-determine another new address for the requesting device  102 - 3  and check the re-determined new address with the DNS server to ensure the availability of the re-determined new address. If the new address or the re-determined new address is available, the DNS server may register the new address or the re-determined new address with the identifier of the requesting device  102 - 3  and reserve the new address or the re-determined new address for the requesting device  102 - 3 . 
     In one implementation, upon confirming the new address to be assigned to the requesting device  102 - 3 , the controlling device  102 - 4  may provide a reply (e.g., a DHCP reply) to the requesting device  102 - 3 . By way of example and not limitation, the reply may include, but is not limited to, the assigned address (e.g., the assigned IPv6 global address), the group key (e.g., the group link-layer key) associated with the ARA network, and/or the configuration information or parameters usable for the requesting device  102 - 3  to join or set up with the ARA network. In one implementation, the controlling device  102 - 4  (or the DHCP server) may send the reply to the requesting device  102 - 3 . In some implementations, with or without the knowledge of a global address of the requesting device  102 - 3  (e.g., since the new address has not been assigned to the requesting device  102 - 3  yet), the controlling device  102 - 4  (or the DHCP server) may send the reply to the requesting device  102 - 3  via the neighboring device  102 - 2  (and the router heading the ARA network if the controlling device  102 - 4  is situated outside the ARA network). For example, the controlling device  102 - 4  (or the DHCP server) may send the reply to the neighboring device  102 - 2  and request that the neighboring device  102 - 2  relay the reply to the requesting device  102 - 3 . The neighboring device  102 - 2 , which has established communication with the requesting device  102 - 3 , may then relay the reply to the requesting device  102 - 3  through a message using the DHCPv6 protocol or a beacon message. Additionally or alternatively, the neighboring device  102 - 2  may broadcast the reply in a neighborhood thereof, and the requesting device  102 - 3 , which is neighboring to the neighboring device  102 - 2 , may receive the broadcasted reply and parse the reply to obtain such information as the assigned new address, etc., to join the ARA network. 
     Upon receiving the reply to the join request, the requesting device  102 - 3  may configure configuration parameters for communication within the ARA network based on, for example, the configuration information or parameters included in the reply. For example, the requesting device  102 - 3  may attach to a routing topology into the ARA network by deciding which routing path and/or neighboring device to use if more than one routing path and/or neighboring devices are available. Additionally or alternatively, the requesting device  102 - 3  may send a message to the root node of the ARA network to notify its arrival to the ARA network, for example. The requesting device  102 - 3  may or may not request or need an acknowledgement from the root node. In an event that an acknowledgement from the root node is requested or needed, the requesting device  102 - 3  may wait for an acknowledgement sent from the root node. In one implementation, if no acknowledgement is received from the root node for a predetermined period of time, the requesting device  102 - 3  may resend the message to the root node. The requesting device  102 - 3  may resend the message for a predetermined number of receipt failures of acknowledgement. Additionally or alternatively, the requesting device  102 - 3  may select a different routing path and/or neighboring device  102  to forward or relay the message to the root node. Upon receiving an acknowledgement from the root node, the requesting device  102 - 3  may start performing normal operations in the ARA network, including, for example, routing and/or forwarding packets that are not destined to the requesting device  102 - 3 , processing packets addressed to the requesting device  102 - 3 , replying for packets (if requested) that are destined to the requesting node  102 - 3 , etc. If no acknowledgement is received from the root node for a predetermined number of retries, the requesting device  102 - 3  may start performing normal operations as if an acknowledgement has been received from the root node, resending the arrival message again after a predetermined time interval, or deciding to migrate to another adjacent ARA network if available, etc. 
     Example Device Migration 
     In some implementations, a device  102  within an ARA network may decide or initiate to leave or migrate from the ARA network to another ARA network. By way of example and not limitation, the device  102  may decide or initiate to leave or migrate from an ARA network (where the device  102  is currently attached) to another ARA network based on one or more network conditions associated with the device  102  and/or the ARA network. For example, the device  102  may initiate to migrate from the ARA network to another ARA network if a communication quality (e.g. a link-layer communication quality) with the device  102  is poor or degraded, for example, below a predetermined quality threshold. Additionally or alternatively, the device  102  may migrate from the ARA network to another ARA network if the router of the ARA network fails. Additionally or alternatively, the device  102  may, while attached to the current ARA network, listen in an environment thereof, and detect or discover existence of other adjacent ARA networks. The device  102  may learn about performance such as quality of service (QoS) offered by these adjacent networks. The device  102  may migrate from the ARA network to another ARA network if the other ARA network offers a better performance such as quality of service than the ARA network to which the device  102  is currently attached. In one implementation, the device  102  may select an adjacent ARA network for migration based on one or more policies or criteria. Examples of these policies or criteria may include, but are not limited to, selecting a network that offers at least a predetermined amount or percentage of improvement over performance such as QoS, time or response latency, throughput, packet drop rate, etc., as compared to the ARA network to which the device  102  is currently attached. 
     Additionally or alternatively, the device  102  may be forced by the controlling device  102 - 4  (or a device  102  in the ARA network such as the router heading the ARA network) to migrate from the ARA network to another ARA network for administrative reasons associated with the ARA network such as overcrowding or overloading of devices in the ARA network, degradation in performance (e.g., increased packet drop rate, decreased available bandwidth, increased collision rate, etc.) associated with the ARA network, load balancing between the ARA network and the another network, etc. Additionally or alternatively, the controlling device  102 - 4  may force the device  102  to migrate from the ARA network to another ARA network if the ARA network is full (e.g., a current load on the ARA network is greater than or equal to a predetermined threshold) and a new device requesting to join the ARA network is an isolated device. 
     In one implementation, in an event that the controlling device  102 - 4  may need to force some device  102  to leave the ARA network or migrate to another ARA network, the controlling device  102 - 4  may determine which one or more devices  102  in the ARA network to leave or to migrate by randomly selecting a device  102  from the ARA network. In some implementations, the controlling device  102 - 4  may select one or more devices to leave or migrate based on information associated with each device in the ARA network. In one implementation, the controlling device  102 - 4  may store the information associated with each device  102  in the ARA network when the respective device  102  joins the ARA network. 
     Additionally or alternatively, the controlling device  102 - 4  may survey each device in the ARA network in response to deciding to force one or more devices  102  in the ARA network to leave or migrate to another ARA network. Additionally or alternatively, the controlling device  102 - 4  may query the devices  102  in the ARA network to determine which of them is/are capable of leaving or migrating from the ARA network. Additionally or alternatively, the controlling device  102 - 4  may retrieve topology information associated with each device  102  in the ARA network from the central office  104  or any device or node that is hierarchically upstream from the controlling device  102 - 4 . In one implementation, the information associated with each device  102  may include, but is not limited to, whether the respective device  102  is an isolated device, whether the respective device  102  has a child device (i.e., device that is hierarchically downstream from the respective device  102 ), how many child devices the respective device  102  has, etc. 
     In response to retrieving information associated with each device  102  in the ARA network or receiving reply from devices in the ARA network, the controlling device  102 - 4  may select which one or more devices  102  in the ARA network to leave or migrate based on one or more heuristics strategies. By way of example and not limitation, the controlling device  102 - 4  may select one or more devices  102  that are not isolated as indicated in the information. Additionally or alternatively, the controlling device  102 - 4  may select one or more devices  102  that have fewer child devices, for example, fewer than a predetermined threshold number. Additionally or alternatively, the controlling device  102 - 4  may select a predetermined number (e.g., one, two, etc.) of the first few devices  102  that have fewer than a threshold number of child devices. Additionally or alternatively, the controlling device  102 - 4  may select one or more devices that are farthest away from the controlling device  102 - 4  based on routing information, for example. 
     Upon selecting the one or more devices  102  to leave or migrate from the ARA network, the controlling device  102 - 4  may send an instruction or request to the one or more devices  102  to leave or migrate from the ARA network. In one implementation, the controlling device  102 - 4  may send the instruction or request to a device  102  and send the instruction or request to another device  102  if the former device  102  cannot leave or migrate from the ARA network for some reason (e.g., the first device would become isolated if it were forced to leave the current ARA network). In some implementations, the controlling device  102 - 4  may send the instruction or request to more than one (or a predetermined number of) devices  102  to avoid the problem of resending the instruction or request to other devices  102  in an event that the previously sent instruction or request cannot be fulfilled by a previously instructed or requested device. 
     In one specific example, the controlling device  102 - 4  may select the device  102 - 5  to leave or migrate from the ARA network. In response to receiving the migration instruction or request, the device  102 - 5  may determine whether there are one or more other ARA networks that the device  102 - 5  may migrate to. For example, the device  102 - 5  may use the discovery module  212  and the broadcasting module  214  to determine whether there are neighboring devices belonging to other ARA networks. If the device  102 - 5  is unable to find other ARA networks to migrate to, the device  102 - 5  may send a message to the controlling device  102 - 4 , refusing to leave the ARA network of the controlling device  102 - 4  since doing so would result in the device  102 - 5  becoming isolated. 
     Alternatively, the device  102 - 5  may detect another ARA network but determine that the quality of communication with this other ARA network is poor or sporadic. In that case, the device  102 - 5  may send a message to the controlling device  102 - 4  indicating that the device  102 - 5  is unable to leave or migrate from the ARA network. Additionally or alternatively, at the time of receiving the migration instruction or request, the device  102 - 5  may determine that the device  102 - 5  is busy in processing, receiving, and/or transmitting data that may need a certain period of time greater than or equal to a predetermined time threshold. In response thereto, the device  102 - 5  may send a message to the controlling device  102 - 4  that the device  102 - 5  is unable to leave or migrate from the ARA network. In one implementation, the device  102 - 5  may be forced to leave or migrate from the ARA network regardless of the consequences of such migration, except that the device  102 - 5  will not be forced to leave or migrate from the ARA network if doing so would result in the device  102 - 5  becoming isolated. 
     In one implementation, if the device  102 - 5  detects another ARA network and determines that the device  102 - 5  is able to leave or migrate from the ARA network, the device  102 - 5  may start to join the other ARA network as described in the example device registration section above. For example, the device  102 - 5  may send a request (which may or may not be encrypted using an encryption key and/or algorithm as described in the foregoing implementations) to a neighboring device  102  belonging to an adjacent ARA network to request joining to the adjacent network. Additionally, the device  102 - 5  may further broadcast a message to devices  102  in the network that the device  102 - 5  is leaving or migrating from, indicating that the device  102 - 5  is leaving the network. In some implementations, since the device  102 - 5  has successfully registered with the NMS previously when joining the ARA network of the controlling device  102 - 4 , the device  102 - 5  may be exempted from some or all of an authentication process as described above (by providing a group key associated with the ARA network and/or a device identifier of the device  102 - 5  to a controlling device of the another ARA network, for example) when joining a new ARA network. 
     In one implementation, the device  102 - 5  may receive a new address that includes a specific prefix (e.g., an IPv6 prefix) designated to the other ARA network. Upon receiving the new address, the device  102 - 5  may update its old address (i.e., an address previously assigned to the device  102 - 5  by the controlling device  102 - 4 ) with the new address at an application level such as at an American National Standards Institute (ANSI) C12.22, DNS, etc. 
     In one implementation, during a time period of the migration and before completion of the migration, the device  102 - 5  may maintain connection or attachment to the ARA network to which it is currently or originally attached. For example, the device  102 - 5  may still perform normal operations in the current ARA network, including routing and forwarding packets not destined to the device  102 - 5 , processing packets addressed to the device  102 - 5 , replying for the packets destined to the device  102 - 5 —if requested—via the current ARA network, etc. Additionally or alternatively, the device  102 - 5  may select a neighboring device  102  from the new ARA network and employ this neighboring device  102  as a relay and/or forwarding device for data packets. Additionally or alternatively, the device  102 - 5  may still receive data packets destined to its old address from other devices  102  in the ARA network. In some implementations, during the time period of the migration, the device  102 - 5  may store or cache its old address and continue to process data or data packets addressed to its old address as usual, thus maintaining a connectivity with the ARA network it is migrating from during this time period of the migration. In one implementation, if the device  102 - 5  has lost connection with its parent devices of the ARA network it is migrating from, the device  102 - 5  may drop all upstream packets (data packets transmitted to devices in a higher hierarchical level of the ARA network) from its buffer, for example. In some implementations, the device  102 - 5  may forward the received data packets to the ARA network it is migrating from (if still attached) during the time period of the migration. In one implementation, if the device  102 - 5  receives its new address and is now attached to another ARA network (i.e., the new ARA network), the device  102 - 5  may “tunnel” the buffered data packets, i.e., data packets coming from its “old” ARA network, and send the received data packets (which are included or encapsulated into new packets, for example) using its new address through the new ARA network, for example. 
     In one implementation, upon successfully attaching or migrating to the new ARA network, the device  102 - 5  detaches itself or leaves from the old ARA network. In one implementation, the device  102 - 5  may send a message to the root node of the old ARA network to notify or announce its departure from the old ARA network. Additionally or alternatively, the device  102 - 5  may send messages (which indicate its departure from the old ARA network) to one or more devices  102  in the old ARA network that forward and/or route their data packets through the device  102 - 5 . These messages (i.e., messages to the root node and/or the other devices  102  in the old ARA network) may or may not request an acknowledgement from the root node and/or the other devices  102  in the old ARA network. Furthermore, in some implementations, the device  102 - 5  may repeatedly send the messages to the root node and/or the other devices  102  in the old ARA network to increase or ensure the likelihood of the root node and/or the other devices  102  receiving the messages. 
     Additionally or alternatively, the device  102 - 5  may stop processing any data packets that are not destined to its old address. In one implementation, the device  102 - 5  may choose to process a data packet if the data packet is a data packet destined to the old address of the device  102 - 5 , and/or a data packet (that may or may not be destined to the old address of the device  102 - 5 ) indicating a high degree of urgency or importance (as indicated by a time at which a response is needed, etc.), for example. Additionally or alternatively, the device  102 - 5  may choose to respond to certain types of data packets that have specific scopes or purposes if the data packets are destined to the old address of the device  102 - 5 . By way of example and not limitation, the device  102 - 5  may process a data packet that carries data destined to a pre-defined set of applications and requires a response from the device  102 - 5 . The device  102 - 5  may send a response via the new ARA network and use a new address of the device  102 - 5  in the new ARA network as a source address of the response. Additionally or alternatively, the device  102 - 5  may ignore or drop data packets that are not one of the specific scopes or destined to the pre-defined set of applications. In some implementations, after the device  102 - 5  has detached from the old ARA network and is performing normal operations in the new ARA network, the device  102 - 5  may still accept packets destined to the old address for a predetermined period of time which may be a default by the old or new ARA network, or may be pre-defined by an administrator of the old or new ARA network. The device  102 - 5  may process data packets destined to its old address (and/or data packets not destined to its old address) according to the foregoing implementations as described above. 
     In some implementations, the old address of the device  102 - 5  will not be re-distributed to another device during a certain period of time, called as a migration time period. This migration time period is set to be long enough to cover an entire ARA switching process until an entire system (including, for example, the root nodes of the old and new ARA networks, DNS server, etc.) is updated to reflect the migration of the device  102 - 5 . 
     Alternative Implementations 
     Although the foregoing implementations describe applications in an autonomous routing area network of an advanced metering infrastructure (AMI), the present disclosure is not limited thereto. In one implementation, the present disclosure can be applied to networks such as cellular networks, home networks, office networks, etc. For example, in an event that a cellular station determines that a load on a cellular network controlled thereby exceeds a predetermined threshold, the cellular station may select and force some of mobile devices connected to its network to leave or migrate to another cellular network, thereby performing load balancing for its controlled network. 
     Exemplary Methods 
       FIG. 3  is a flow chart depicting an example method  300  of device registration in a network.  FIG. 4  is a flow chart depicting an example method  400  of determination whether to allow or reject a device to join a network.  FIG. 5  is a flow chart depicting an example method  500  of device migration from a network. The methods of  FIG. 3 ,  FIG. 4  and  FIG. 5  may, but need not, be implemented in the environment of  FIG. 1  and using the device of  FIG. 2 . For ease of explanation, methods  300 ,  400  and  500  are described with reference to  FIGS. 1 and 2 . However, the methods  300 ,  400  and  500  may alternatively be implemented in other environments and/or using other systems. 
     Methods  300 ,  400  and  500  are described in the general context of computer-executable instructions. Generally, computer-executable instructions can include routines, programs, objects, components, data structures, procedures, modules, functions, and the like that perform particular functions or implement particular abstract data types. The methods can also be practiced in a distributed computing environment where functions are performed by remote processing devices that are linked through a communication network. In a distributed computing environment, computer-executable instructions may be located in local and/or remote computer storage media, including memory storage devices. 
     The exemplary methods are illustrated as a collection of blocks in a logical flow graph representing a sequence of operations that can be implemented in hardware, software, firmware, or a combination thereof. The order in which the methods are described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method, or alternate methods. Additionally, individual blocks may be omitted from the method without departing from the spirit and scope of the subject matter described herein. In the context of software, the blocks represent computer instructions that, when executed by one or more processors, perform the recited operations. 
     Referring back to  FIG. 3 , at block  302 , the requesting device  102 - 3  may want to join a network covering an area where the requesting device  102 - 3  is located. The requesting device  102 - 3  may discover the neighboring device  102 - 2  and sends a join request (e.g., a DHCPv6 request or a beacon message including the join request) to the neighboring device  102 - 2 . 
     At block  304 , in response to receiving the join request, the neighboring device  102 - 2  may parse the request and determine that the requesting device  102 - 3  requests to join a network of which the neighboring device  102 - 2  is a member. 
     At block  306 , in response to determining that the requesting device  102 - 3  requests to join the network, the neighboring device  102 - 2  may optionally filter the join request. In one implementation, the neighboring device  102 - 2  may determine whether to relay the join request to other devices of the network. For example, the neighboring device  102 - 2  may have received an instruction or request from the controlling device  102 - 4  that no devices except isolated devices may be accepted to the network for administrative or networking reasons such as overcrowding or overloading of the network. In this case, the neighboring device  102 - 2  may determine whether the requesting device  102 - 3  is an isolated device based on, for example, information included in the join request. In one implementation, if the neighboring device  102 - 2  has received the instruction or request that no devices except isolated devices may be accepted to the network and the requesting device  102 - 3  is not an isolated device, the neighboring device  102 - 2  may send a response to the requesting device  102 - 3 , indicating that the join request is rejected. Otherwise, the neighboring device  102 - 2  may prepare to relay the join request of the requesting device  102 - 3  to other devices of the network. 
     At block  308 , the requesting device  102 - 3  receives the response from the neighboring device  102 - 2  indicating that the join request thereof is rejected. 
     At block  310 , the neighboring device  102 - 2  may relay the join request to the controlling device  102 - 4  or the parent device of the neighboring device  102 - 2  based on whether the neighboring device  102 - 2  knows the address of the controlling device  102 - 4 . 
     At block  312 , in response to receiving the join request relayed from the neighboring device  102 - 2 , the controlling device  102 - 4  may determine whether to allow or reject the join request of the requesting device  102 - 3 . In one implementation, the controlling device  102 - 4  may determine whether to allow the join request based on a condition of the network and/or a condition of the requesting device  102 - 3 . If the controlling device  102 - 4  determines to reject the join request of the requesting device  102 - 3 , the controlling device  102 - 4  may send a reply to the requesting device  102 - 3  via the neighboring device  102 - 2 , indicating that the controlling device  102 - 4  or the network is unable to allow the requesting device  102 - 3  to join. 
     At block  314 , in response to determining to allow the request of the requesting device  102 - 3 , the controlling device  102 - 4  may send a message including an identifier and/or an authentication signature of the requesting device  102 - 3  included in the join request of the requesting device  102 - 3  to an authentication server (e.g., AAA server  120 ). In one implementation, the controlling device  102 - 4  may further sign or encrypt the message using a group key associated with the network or an encryption key associated with the controlling device  102 - 4 . 
     At block  316 , upon receiving the message, the authentication server  120  may decrypt the message if encrypted, and parse the message to obtain the identifier and/or the authentication signature of the requesting device  102 - 3 . The authentication server  120  may then perform authentication based on the obtained identifier and/or the obtained authentication signature of the requesting device  102 - 3 . In response to successfully authenticating an identity of the requesting device  102 - 3 , the authentication server  120  may send a successful authentication message possibly including a group key associated with the network (which may or may not be encrypted using a public or symmetric key of the requesting device  102 - 3 ) to the controlling device  102 - 4 . In one implementation, the public or symmetric key of the requesting device  102 - 3  may be known only to the requesting device  102 - 3  and the authentication server  120 . In some implementations, the public or symmetric key of the requesting device  102 - 3  may further be known to other devices or servers (such as the central office  104  and/or the controlling device  102 - 4 , for example) of the ARA network that are responsible for network management or monitoring. For example, the authentication server  120  may send the successful authentication message that further includes the public or symmetric key of the requesting device  102 - 3  that has been encrypted using the group key associated with the ARA network. Alternatively, if the authentication server  120  fails to authenticate the identity of the requesting device  102 - 3 , the authentication server  120  may send a failed authentication message to the controlling device  102 - 4 , indicating that the authentication is failed. 
     At block  318 , in response to receiving a message from the authentication server  120 , the controlling device  102 - 4  may determine whether the authentication of the identity of the requesting device  102 - 3  is successful. If failed, the controlling device  102 - 4  may send a reply to the requesting device  102 - 3  via the neighboring device  102 - 2 , indicating that the join request of the requesting device  102 - 3  is denied. In response to determining that the identity of the requesting device  102 - 3  is successfully authenticated, the controlling device  102 - 4  may send an admission response to the requesting device  102 - 3  via the neighboring device  102 - 2  including a message indicating that the join request of the requesting device  102 - 3  is allowed. In one implementation, the response may further include, but is not limited to, a group key associated with the network that may or may not be encrypted at the authentication server using the public or symmetric key of the requesting device  102 - 3 . Additionally or alternatively, in some implementations, the controlling device  102 - 4  may encrypt the response using a public or symmetric key of the requesting device  102 - 3  if the controlling device  102 - 4  knows the public or symmetric key of the requesting device  102 - 3 , for example, from the authentication server  120 . Additionally or alternatively, in one implementation, the controlling device  102 - 4  may encrypt the group key (and/or other information related to joining the network) using the public or symmetric key of the requesting device  102 - 3  (if this public or symmetric key is known to the controlling device  102 - 4 ) and encrypt the encrypted group key and/or the message using the group key associated with the network. In some implementation, the controlling device  102 - 4  may encrypt the group key and the message using the public or symmetric key of the requesting device  102 - 3 , and further encrypt the encrypted group key, encrypted message, and/or other information (such as information that enables routing the response to the requesting device  102 - 3 , e.g., an address of the neighboring device  102 - 2  and/or an identity of the requesting device  102 - 3 , etc.) using the group key. 
     In some implementations, the controlling device  102 - 4  may not send an admission response to the requesting device  102 - 3  upon receiving a successful identity authentication of the requesting device  102 - 3  from the authentication server  120  (i.e., after determining that the identity of the requesting device  102 - 3  is successfully authenticated). In these alternative implementations, the controlling device  102 - 4  may optionally send a registration request to the NMS to register the requesting device  102 - 3  with the NMS or the central office  104  as described at block  324  below. 
     At block  320 , the neighboring device  102 - 2  may receive and parse the admission response sent from the controlling device  102 - 4 . In one implementation, if the response is encrypted using the group key associated with the network, the neighboring device  102 - 2  may decrypt the encrypted response. In one implementation, in response to determining that the admission response is a response related to the join request of the requesting device  102 - 3 , the neighboring device  102 - 2  may relay part or all of the response to the requesting device  102 - 3 . For example, the neighboring device  102 - 2  may relay part of the response that is encrypted using the public or symmetric key of the requesting device  102 - 3  to the requesting device  102 - 3 . 
     At block  322 , the requesting device  102 - 3  receives the response relayed from the neighboring device  102 - 2  and parses the response to retrieve a result of the join request and/or the group key of the network (if included). The requesting device  102 - 3  may start to receive data from and/or send data to other devices of the network using the group key. 
     At block  324 , the controlling device  102 - 4  may optionally send a registration request to the NMS to register the requesting device  102 - 3  with the NMS or the central office  104 . The registration request may include, but is not limited to, an identifier of the requesting device  102 - 3 . 
     At block  326 , in response to receiving the registration request from the controlling device  102 - 4 , the NMS may obtain information associated with the network and information associated with the requesting device  102 - 3  therein or from other devices. The NMS may determine configuration information or parameters usable for the requesting device  102 - 3  based on the obtained information. For example, the NMS may determine configuration information or parameters usable for the requesting device  102 - 3  based on a type of the requesting device  102 - 3 , a type of the network, etc. Upon determining the configuration information or parameters, the NMS may send the configuration information or parameters to the controlling device  102 - 4 . 
     At block  328 , in response to obtaining the configuration information or parameters from the NMS, the controlling device  102 - 4  may assign a new address to the requesting device  102 - 3 . In one implementation, the controlling device  102 - 4  may assign a new address that includes a prefix specified or designated to the network. The controlling device  102 - 4  may further prepare a reply (e.g., a DHCP reply) to the requesting device  102 - 3 . In one implementation, the reply may include, but is not limited to, the assigned new address, the configuration information or parameters, and/or the group key associated with the network. In one implementation, if the controlling device  102 - 4  has not sent an admission response to the requesting device  102 - 3  immediately after determining that the identity of the requesting device  102 - 3  is successfully authenticated, sending this reply from the controlling device  102 - 4  may indicate the successful authentication of the identity of the requesting device  102 - 3 . In some implementations, the controlling device  102 - 4  may further merge information received from the authentication server  120  related to the authentication of the identity of the requesting device  102 - 3  into the reply. In one implementation, the controlling device  102 - 4  may send the reply to the requesting device  102 - 3  via the neighboring device  102 - 2  (and a router heading the network if the controlling device is located outside the network). 
     At block  330 , the neighboring device  102 - 2  relays the reply from the controlling device  102 - 4  to the requesting device  102 - 3 . 
     At block  332 , the requesting device  102 - 3  successfully joins and registers with the network using information (e.g., the group key, the assigned address, and/or the configuration information or parameters) received in the reply. In one implementation, the requesting device  102 - 3  may further authenticate the network if the symmetric or asymmetric key of the requesting device  102 - 3  is known only to itself and one or more authorized devices and/or servers (e.g., the authentication server  120 , the central office  104 , and/or the controlling device  102 - 4 ). For example, the group key that is included in the reply may be encrypted using the symmetric or asymmetric key (e.g., the public key) of the requesting device  102 - 3 . The requesting device  102 - 3  may therefore authenticate the network if the requesting device  102 - 3  can decrypt the encrypted group key using its symmetric or asymmetric key (e.g., the private key), and can successfully communicate with other devices of the ARA network using that decrypted group key. If, however, the requesting device  102 - 3  cannot communicate data with other devices using the decrypted group key, the requesting device  102 - 3  may determine that the authentication of the network fails, and leave (or disconnect from) the network accordingly. 
     Referring back to  FIG. 4 , at block  402 , the controlling device  102 - 4  may receive a request from the requesting device  102 - 3  via the neighboring device  102 - 2 . The requesting device  102 - 3  may include a device newly deployed within the network or a device attempting to migrate to the network from another network. In one implementation, the controlling device  102 - 4  may determine that the request of the requesting device  102 - 3  is a join request, requesting to join the network associated with the controlling device  102 - 4 . The join request may at least include information about whether the requesting device  102 - 3  is an isolated device. In some implementations, the join request may further include, but is not limited to, an identity of the requesting device  102 - 3 , etc. In one implementation, the join request may be encrypted or signed by a private or symmetric key of the requesting device  102 - 3 . The controlling device  102 - 4  may decrypt the request using the public or symmetric key of the requesting device  102 - 3  if the request has been encrypted. 
     At block  404 , in response to determining that the request is a join request, the controlling device  102 - 4  may determine whether the network has a capacity to accommodate additional devices. For example, the controlling device  102 - 4  may determine whether a load associated with the network is greater than or equal to a predetermined threshold. A load associated with the network may include, but is not limited to, a current number of devices, a current traffic, a current or average packet drop rate, a current or average bandwidth usage, etc. 
     At block  406 , if the controlling device  102 - 4  determines that the network can accommodate additional devices, e.g., the load is less than the predetermined threshold, the controlling device  102 - 4  may proceed to process the join request of the requesting device  102 - 3  as described in the foregoing implementations, e.g.,  FIG. 3 , with other devices and/or servers. 
     At block  408 , if the controlling device  102 - 4  determines that the network cannot accommodate additional devices, e.g., the load has exceeded the predetermined threshold, the controlling device  102 - 4  may determine whether the requesting device  102 - 3  is an isolated device based on, for example, information included in the join request. 
     At block  410 , if the controlling device  102 - 4  determines that the requesting device  102 - 3  is not an isolated device, the controlling device  102 - 4  may reject the join request of the requesting device  102 - 3  and send a response of rejection to the requesting device  102 - 3  via the neighboring device  102 - 2 . 
     At block  412 , if the controlling device  102 - 4  determines that the requesting device  102 - 3  is an isolated device, the controlling device  102 - 4  may proceed to process the join request of the requesting device  102 - 3  as described in the foregoing implementations, e.g.,  FIG. 3 , with other devices and/or servers. Furthermore, the controlling device  102 - 4  may force one or more devices of the network to leave or migrate from the network as described in the foregoing implementations and will be described in  FIG. 5  and accompanying descriptions below. 
     Referring back to  FIG. 5 , at block  502 , the controlling device  102 - 4  decides to force one or more devices  102  to leave or migrate from the network. The controlling device  102 - 4  may make this decision based on one or more reasons such as load balancing of the network, request of an isolated device to join an already overloaded network, etc. 
     At block  504 , the controlling device  102 - 4  may select one or more devices  102  in the network to leave or migrate based on one or more heuristics strategies. The one or more heuristics strategies may include, but are not limited to, selecting devices that are not isolated, selecting devices that have no or fewer number of child devices, selecting devices that are communicatively farthest from the controlling device. 
     At block  506 , upon selecting the one or more devices to leave or migrate, the controlling device  102 - 4  may send an instruction or request to the one or more devices, forcing or requesting the one or more devices to leave or migrate from the network. 
     At block  508 , in response to receiving the migration instruction or request, the one or more devices, e.g., the device  102 - 5 , may determine that the device  102 - 5  is able to leave or migrate from the network. In one implementation, the device  102 - 5  may determine whether the device  102 - 5  is currently an isolated device by detecting or discovering whether one or more networks (other than the network the device  102 - 5  is currently a member) exist in an area in which the device  102 - 5  is located. The device  102 - 5  may send a message to the controlling device  102 - 4  in response to determining that the device  102 - 5  is unable to leave or migrate to another network. 
     At block  510 , in response to determining that one or more networks (other than the network the device  102 - 5  is currently a member) exist, the device  102 - 5  may begin to join one of the one or more networks as described above with respect to  FIG. 3 , for example. Additionally, the device  102 - 5  may further broadcast a message to devices  102  in the network that the device  102 - 5  is leaving or migrating from the network. 
     At block  512 , during a time period of migration and before completion of the migration, in response to receiving data packets destined to an “old” address (i.e., an address assigned to the device  102 - 5  by the network from which the device  102 - 5  is leaving or migrating) of the device  102 - 5 , the device  102 - 5  may drop the data packets, or forward the data packets to other devices in the network that the device  102 - 5  is still connected to. 
     At block  514 , upon successfully obtaining the new address and attaching to the new network, the device  102 - 5  may start performing its normal or assigned operations or functions in the new network. 
     Although  FIG. 5  describes that the device  102 - 5  may be forced or instructed to leave or migrate from the ARA network by the controlling device  102 - 4 , in some implementations, the device  102 - 5  actually initiates on its own to leave or migrate from the ARA network to another ARA network. By way of example and not limitation, the device  102 - 5  may decide or initiate to leave or migrate from the ARA network to another ARA network based on one or more network conditions associated with the device  102 - 5  and/or the ARA network. For example, the device  102 - 5  may initiate to migrate from the ARA network to another ARA network if a communication quality (e.g. a link-layer communication quality) with the device  102 - 5  is poor or degraded, for example, below a predetermined quality threshold. Additionally or alternatively, the device  102 - 5  may migrate from the ARA network to another ARA network if the router of the ARA network fails. Additionally or alternatively, the device  102 - 5  may, while attached to the current ARA network, listen it an environment thereof, and detect or discover existence of other adjacent ARA networks. The device  102 - 5  may learn about performance/quality of service offered by these adjacent networks. The device  102 - 5  may migrate from the ARA network to another ARA network if the other ARA network offers a better performance/quality of service than the ARA network to which the device  102 - 5  is currently attached. 
     Any of the acts of any of the methods described herein may be implemented at least partially by a processor or other electronic device based on instructions stored on one or more computer-readable media. By way of example and not limitation, any of the acts of any of the methods described herein may be implemented under control of one or more processors configured with executable instructions that may be stored on one or more computer-readable media such as one or more computer storage media. 
     CONCLUSION 
     Although the invention has been described in language specific to structural features and/or methodological acts, it is to be understood that the invention is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the invention.