COMMUNICATION APPARATUS AND NETWORK CONNECTION METHOD

A communication apparatus that, when a device connects to an external network via another device, is capable of reducing the user's workload when connecting. The apparatus includes: a WLAN control unit that uses a WLAN to communicate with a WLAN STA device that communicates with an external network; a BT control unit that uses BT to communicate with a BT device capable of communicating with the external network; a connection history DB that stores therein information on connections to the BT devices and the order of priority for connecting to the BT devices; and a connection management unit that refers to the connection history DB. The communication apparatus connects to the WLAN STA device and to the BT device, and enables the WLAN STA device to communicate with the external network via the own apparatus and the BT device.

FIELD

The present invention relates to a communication apparatus that connects to an external network via another device.

BACKGROUND

In the conventional arts, it is assumed that most wireless LAN (WLAN: Wireless Local Area Network) APs (Access Points) are set up inside homes. The AP connects to a single always-connected line (for example, FTTH (Fiber To The Home) or ADSL (Asymmetric Digital Subscriber Line)) via a modem or the like. When a WLAN STA (Station) connects to the AP, the AP provides communication by using the backbone circuit that is connected to the AP.

In recent years, Aps, for which it is assumed they will be used outside the home (for example, a mobile router and the like), have become more widespread. The AP has a SIM (Subscriber Identity Module) card for connecting to a cellular network circuit (for example, 3G or LTE (Long Term Evolution)) inserted therein. When the STA connects to the AP, the AP provides communication by using the cellular network circuit.

Specifically, a technique has been disclosed in Patent Literature 1 mentioned below, in which a mobile phone that can be connected to the Internet connects to a host device by using Bluetooth®, a WLAN, or the like in order to provide an Internet connection and a host-to-host connection for the host device. Further, a technique has been proposed in Patent Literature 2 mentioned below in which a mobile phone is equipped with a wireless LAN function and a router function; and a router unit analyzes transmission data so as to determine whether to connect to the Internet.

With an AP for which it is assumed it will be used outside the home, the AP itself connects directly to an external network (for example, the Internet) and therefore is capable of directly controlling a connection to the external network depending on the connection of the STA to the AP. Consequently, the user does not need to operate the AP. Moreover, with the techniques described in Patent Literatures 1 and 2 mentioned below, a mobile phone connects directly to an external network and therefore there is neither need to perform a connection process to a device other than the STA nor to set network settings for a device connected to the mobile phone.

CITATION LIST

Patent Literatures

SUMMARY

Technical Problem

However, with the above conventional techniques, in a case where an AP (a communication apparatus) connects to another device that provides a connection to an external network by means of Bluetooth®, a USB (Universal Serial Bus), or the like, and further connects to an external network via another device connected to the AP, there is a problem in that the user needs to perform certain functions in order to connect the AP to the another device.

The present invention has been achieved to solve the above problems, and an objective of the present invention is to provide a communication apparatus that, when a device is to be connected to an external network via an apparatus to which the device belongs as well as another device, is capable of reducing the user's workload during the connecting.

Solution to Problem

To solve the problem and objective, the present invention relates to a communication apparatus that includes: a first communication-control unit that uses a first communication mode to communicate with a first communication device that is to communicate with an external network; a second communication-control unit that uses a second communication mode to communicate with a second communication device that is capable of communicating with the external network; a connection-history storage unit that stores therein information on a connection to the second communication device and order of priority for connecting to the second communication device; and a connection management unit that refers to the connection-history storage unit to manage a connection to the first communication device and a connection to the second communication device. The communication apparatus connects to the first communication device and to the second communication device, and enables the first communication device to communicate with the external network via the own apparatus and the second communication device.

Advantageous Effects of Invention

According to the present invention, the communication apparatus can reduce, when a device connects to an external network via an apparatus to which the device belongs and connects to another device, the user's workload during the connecting.

DESCRIPTION OF EMBODIMENTS

Exemplary embodiments of a communication apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments.

First Embodiment

FIG. 1illustrates a configuration example of a communication network according to the present embodiment. The communication network includes an AP (Access Point)1, a WLAN (Wireless Local Area Network) STA (Station)2, BTs (Bluetooth)3and4, and a base station5.

The AP1is a communication apparatus that has a

WLAN-AP function and a BT function. The AP1connects to the BTs3and4that provide the function of connecting to an external network via the ET, and provide the function of connecting an external network to the WLAN STA2that connects to the AP1. For example, the AP1is a mobile router, a PC (personal computer), or an in-vehicle device, but is not limited thereto.

The WLAN STA2is a WLAN STA device equipped with a WLAN function and is a first communication device that desires to communicate with an external network. For example, the WLAN STA2is a PC, a Smartphone, or a tablet device, but is not limited thereto.

The BTs3and4are BT devices that have the BT function and are second communication devices that are capable of communicating with the external network via the base station5. The BTs3and4are equipped with a profile that provides the function of connecting to the external network, such as a DUN (Dial-up Networking Profile) or a PAN (Personal Area Networking Profile). For example, the BTs3and4are mobile phones, but are not limited thereto.

The base station5is a mobile-phone base station, to which the BTs3and4or other devices connect. The base station5connects to the Internet, which is an external network. InFIG. 1, the base station5connects to the BT3over the 3G and connects to the BT4over the LTE as an example, but is not limited thereto. For example, the base station5can use WiMAX to connect to the BTs3and4.

InFIG. 1, the communication network is configured from one WLAN STA device (the WLAN STA2) and two BT devices (the BTs3and4). However, there can be a plurality of WLAN STA devices and a plurality of BT devices in the communication network.

Next, the configuration of the AP1is described.FIG. 2illustrates a configuration example of the AP1. The AP1includes a WLAN control unit11, a BT control unit12, a connection management unit13, and a connection history database (DB)14.

The WEAN control unit11executes control of WLAN communication. In the present embodiment, the WLAN operates as an AP. The basic operation of the WLAN follows the “IEEE, “IEEE Std IEEE 802.11-2007”, 12 Jun. 2007”.

However, the WLAN is not particularly limited thereto as long as it can be connected to the WLAN STA2illustrated inFIG. 1.

The BT control unit12executes control of BT communication. The BT according to the present embodiment is equipped with at least one profile that provides the function of connecting to an external network, such as the DUN or PAN. The basic operation of BT follows “Bluetooth, “Specification of Bluetooth System Covered Core Package Version: 4.0”, 30 Jun. 2010”. However, the version of BT and the like are not particularly limited thereto as long as BT can be connected to the BTs3and4illustrated inFIG. 1.

The connection management unit13manages WLAN communication and BT communication and calls out necessary information from the connection history DB14so as to manage each connection.

The connection history DB14is a storage unit that stores therein the following: device information on an STA, a BT, and the like to which the AP1has connected previously; information required for a connection, such as a password; setting-value information to be used for a BT device to connect to a network; and other information.

Next, a network connection process for the AP1according to the present embodiment is described.FIG. 3is a sequence diagram illustrating the network connection process according to the present embodiment. In the initial state illustrated inFIG. 3, it is assumed that the AP1, and the BTs3and4have already been paired; information, such as a BDAddr (Bluetooth Device Address), a Link key, and an APN (Access Point Network) setting, has been registered in the connection history DB14; and connection priorities has been given to each BT device.

FIG. 4illustrates a registration example of information registered in the connection history DB14according to the present embodiment.FIG. 4illustrates a state where the DT3has been registered as connection priority1, the DT4has been registered as connection priority2, and their respective BDAddrs, Link keys, and APN settings have also been registered.

In the initial state inFIG. 3, it is assumed that connections of the AP1to the WLAN STA2, and the BTs3and4are not established.

A specific network connection process is described below. First, the WLAN STA2that starts a connection to an external network inquires about a peripheral AP by receiving a Beacon transmitted from the AP1or by transmitting a Probe Request to the AP1(Step S101).

The WLAN STA2, having decided to connect to the AP1as a result of the inquiry at Step S101, performs an authentication process (Step S102) and a connection process (Step S103) to establish a connection between the WLAN STA2and the AP1. The detailed processes at Steps S101to S103are the same as those described in the IEEE 802.11 standards.

In the AP1, having established a connection to the WLAN STA2, the connection management unit13confirms whether there is a connection to an external network. When the AP1is connected to an external network, the connection management unit13uses the established connection to provide a connection to the external network for the WLAN STA2. Because in this example the AP1is in a state where there is not a connection to the external network, the connection management unit13searches for a connecting BT device in the connection history DB14(Step S104). In the AP1, the connection management unit13attempts to connect to a BT device in the order of connection priority and accordingly selects the BT3as the first connection target.

In the AP1, the connection management unit13starts connecting to the BT3selected at Step S104by using the BT control unit12(Step S105). The connection management unit13obtains the BDAddr, the Link key, and other information, which are required for the connection, from the connection history DB14.

In this example, the BT function of the BT3is OFF, and therefore the connection process is assumed to have failed. In this case, a timeout occurs in the connection process, and the connection management unit13searches for a BT device to be the next connection option in the connection history DB14. The connection process fails also when the BT3is not within communication range or when power is turned off. Further, the connection process fails also when a profile connection fails because a BT device is not compatible with the DUN or PAN.

The connection management unit13in the AP1searches for the next connecting BT device in the connection history DB14in the same manner as Step S104(Step S106). In the AP1, the connection management unit13attempts to sequentially connect to a BT device with the second highest connection priority after the BT3and accordingly selects the BT4as a second connection target.

In the AP1, the connection management unit13starts connecting to the BT4selected at Step S106by using the BT control unit12in the same manner as Step S105(Step S107). In this example, the AP1is assumed to have completed the connection to the BT4.

In the AP1, the connection management unit13executes a profile connection with the BT4connected to the AP1via the BT control unit12(Step S108). The connecting profile is the DUN, PAN, or the like that provides a connection to an external network. The connection management unit13obtains information required for a network connection from the connection history DB14.

The AP1connects to the WLAN STA2and to the BT4that is capable of communicating with the external network and is therefore capable of providing the WLAN STA2with communication with the external network via the apparatus it belongs to and the BT4. The WLAN STA2can communicate with the external network via the communication apparatus and the BT4.

As an example, the completion of a connection between the WLAN STA2and the AP1is used as a trigger to start connecting the AP1to a BT device. However, the present invention is not limited thereto. For example, the transmission and reception of the message during the authentication process or the connection process can be used as a trigger to start connecting the AP1to the BT device, or when an Internet connection request from a browser or the like is issued, as a trigger for the AP1and the BT device to start connecting to each other.

When the connection of the AP1and the BT device is completed and only the profile connection has not yet been executed, it is possible to omit the process at Step S107.

In the present embodiment, a case has been described where there is not a connection between the AP1and a BT device in the initial state. However, when there is a connection of the AP1and a BT device, the AP1can treat the connected BT device as a device with the highest connection priority. When the profiles are not compatible with each other, it is also possible for the connection management unit13in the AP1to search in the connection history DB14.

The connection priority assigned to a BT device can be set in advance by a user, or it can be automatically determined and set by the AP1by registering the fee structure (such as a fixed fee or on an as-used basis) and the line information (such as 3G, LTE, or WiMAX). By registering the profile information supported by a BT device in the connection history DB14, it is also possible to transmit a connection request only to a BT device that supports the DUN or PAN.

When a user operation such as inputting a PIN code occurs in a case, for example, where the Link key is deleted in a connection-target BT device, then the AP1can cancel the connection and select the next connection-target BT device.

The AP1can store in advance in a DB the APN setting and other information required for connecting to an external network. This also makes it possible to automatically perform the APN setting suitable for each carrier on the basis of operator information obtained from an AT command or the like.

In the present embodiment, a BT-connected mobile phone has been described as an example of a device that provides a connection to an external network (hereinafter, “external-network connection device”). However, other connection modes such as a USB and a WLAN are also applicable to a mobile phone.

As described above, according to the present embodiment, in the network configuration in which an AP connects to an external network via another device, a connection of a WLAN STA device and the AP is used as a trigger to automatically connect the AP to an external-network connection device. Therefore, a user does not need to perform a process to connect the AP to the external-network connection device in order for the WLAN STA device to communicate with the external network; and thus the user's workload during connection can be reduced.

By setting the connection priority in the AP, it is possible to give the connecting devices the user prefers a higher connection priority. As the AP sets connection priority automatically on the basis of the fee structure, the communication speed, and the like, it is therefore possible to connect to an optimum external-network connection device.

Second Embodiment

In the present embodiment, a case where two WLAN STAs are provided is described. The parts different from those in the first embodiment are described here.

FIG. 5illustrates a configuration example of a communication network according to the present embodiment. When compared with the communication network inFIG. 1, a WLAN STA6is added. While the AP1has the same configuration as in the first embodiment (seeFIG. 2), the item “list of WLAN STAs”, which are permitted to connect to certain BT devices, is added to the connection history DB14according to the present embodiment.

Next, a network connection process in the AP1according to the present embodiment is described.FIG. 6is a sequence diagram illustrating the network connection process according to the present embodiment. In the initial state inFIG. 6, it is assumed that the AP1, and the BTs3and4have already been paired; information, such as a BDAddr, a Link key, and an APN setting, has been registered in the connection history DB14; and the connection priority and a connection-permitted WLAN STA have been assigned to each BT device.

FIG. 7illustrates a registration example of information registered in the connection history DB14according to the present embodiment. When compared with the items in the first embodiment (seeFIG. 4), the item “connection-permitted WLAN STAs” is an addition. In this example, the BT3is permitted to connect to the WLAN STA2, and the FT4is permitted to connect to the WLAN STA2and the WLAN STA6.

That is,FIG. 7illustrates that as a FT device to be used for communicating with an external network, the WLAN STA2can use the BTs3and4, but the WLAN STA6can use only the BT4.

In the initial state illustrated inFIG. 5, it is assumed that the connections of the AP1, the WLAN STAs2and6, and the BTs3and4are not established.

A specific network connection process is described below. The processes at Steps S201to S203are the same as the processes at Steps S101to S103in the first embodiment.

In the AP1, having established a connection to the WLAN STA2, the connection management unit13confirms whether there is a connection to an external network. When the AP is connected to the external network, the connection management unit13confirms whether a connected BT device, which is connected from the connection history DB14, has permitted a connection to the WLAN STA2. When the connection is permitted, the connection management unit13uses the established connection so as to provide a connection to the external network for the WLAN STA2. When there is no connection to the external network, or when the connected BT device does not permit a connection for the WLAN STA2, the connection management unit13in the AP1selects a connection-target BT device from the connection history DB14. Because, in this example, the AP1is in a state where there is no connection to the external network, the connection management unit13searches for a connecting BT device from the connection history DB14(Step S204). In the AP1, the connection management unit13selects the BT3as a first connection target because a connection to the WLAN STA2is permitted and also because the connection management unit13tries to connect to a BT device in the order of connection priority.

In the AP1, the connection management unit13starts connecting to the ET3selected at Step S204via the BT control unit12(Step S205). In this example, the AP1is assumed to have completed the connection to the BT3.

In the AP1, the connection management unit13executes a profile connection with the ET3connected to the AP1through the BT control unit12(Step S206). The connecting profile is the DUN, PAN, or the like that provides a connection to an external network. The connection management unit13obtains information required for a network connection from the connection history DB14.

Next, the KLAN STA6that starts a connection to an external network inquires about a peripheral AP by receiving a Beacon transmitted from the AP1or by transmitting a Probe Request (Step S207).

The WLAN STA6, having decided to connect to the AP1as a result of the inquiry at Step S207, performs an authentication process (Step S208) and a connection process (Step S209) to establish a connection between the KLAN STA6and the AP1.

In the AP1, having established a connection to the WLAN STA6, the connection management unit13confirms whether there is a connection to an external network. Upon recognizing that the AP1is connected to the external network through the BT3, the connection management unit13confirms with the connection history DB14whether the BT3permits a connection to the WLAN STA6. Because in this example, the connection to the WLAN STA6is not permitted, the connection management unit13searches for a connecting BT device in the connection history DB14(Step S210). In the AP1, the connection management unit13selects the BT4as a first connection target because the connection to the WLAN STA6is permitted and also because the connection management unit13attempts to connect to a BT device in the order of connection priority.

In the AP1, the connection management unit13starts connecting to the BT4selected at Step S210through the BT control unit12(Step S211). Here, the AP1is assumed to have completed the connection to the BT4.

In the AP1, the connection management unit13executes a profile connection with the BT4connected to the AP1via the BT control unit12(Step S212). The connecting profile is the DUN, PAN, or the like that provides a connection to an external network. The connection management unit13obtains information required for a network connection from the connection history DB14.

The AP1connects to the WLAN STA2and to the BT3, which is capable of communicating with the external network, so as to therefore be capable of providing communication with the external network via its own apparatus and the BT3to the WLAN STA2. The WLAN STA2can communicate with the external network via the communication apparatus and the BT3.

The AP1connects to the WLAN STA6and to the BT4capable of communicating with the external network and is therefore capable of providing communication with the external network via the own apparatus and the BT4to the WLAN STA6. The WLAN STA6can communicate with the external network via the communication apparatus and the BT4.

In the present embodiment, the BT3is used by the WLAN STA2to connect to the external network, and the BT4is used by the WLAN STA6to connect to the external network; while the BT4also permits a connection to the WLAN STA2. Therefore, after the completion of a connection to the BT4, the connection for the WLAN STA2to the external network can be changed from the BT3to the BT4; and therefore the connection with the BT3can be cut. By not restricting connection-permitted WLAN STAs, it is also possible to use a BT device for all the connected WLAN STAs to connect to an external network.

In a case where the AP1can handle a plurality of SSIDs (Service Set Identifiers), a BT device to be used for connecting to an external network can be selected on the basis of the SSID designated for the connection by a WLAN STA device. Further, the AP1can prepare a plurality of passphrases, and therefore it is also possible to select a FT device to be used for connecting to an external network on the basis of the passphrase used for the connection for a WLAN STA device.

The completion of a connection between a WLAN STA device and the AP1is one example of a trigger used to start connecting the AP1with a BT device. However, the present invention, similarly to the first embodiment, is not limited thereto. For example, message transmission and reception during the authentication process or the connection process can be used as a trigger to start connecting the AP1with the BT device; or when an Internet connection request from a browser or the like is issued, the AP1and the BT device can start connecting to each other.

When the connection of the AP1and the BT device has been completed, but only the profile connection has not yet been executed, then it is possible to omit the processes at Steps S205and S211.

In the present embodiment, there has been described a case where there is no connection of the AP1and a BT device in the initial state. However, when there is a connection of the AP1and a BT device, the AP1can treat, similarly to the first embodiment, the connected BT device as a device with the highest connection priority. When their profiles are not compatible with each other, it is also possible for the connection management unit13in the AP1to search the connection history DB14.

Connection priority assigned to a BT device can be set in advance by a user, or can be automatically determined and set by the AP1by registering the fee structure (such as a fixed fee or on an as-used basis) and the line information (such as 3G, LTE, or WiMAX), similarly to the first embodiment. By registering profile information supported by a BT device in the connection history DB14, it is also possible to transmit a connection request only to a BT device that supports the DUN or PAN.

When a user operation such as inputting a PIN code is performed in a case, for example, where the Link key is deleted in a connection-target BT device, then the AP1can cancel the connection and select the next connection-target BT device, similarly to the first embodiment.

In the case where the AP1connects to a plurality of external-network connection devices, the AP1can connect to WLAN STAs in such a manner as to distribute loads on the basis of the traffic volume resulting from usage of each of the devices, the line information, the connection-permitted WLAN STAs, and other information.

The AP1has stored in advance in a DE the APN setting and other information required for connecting to an external network. This also makes it possible to automatically perform the APN setting suitable for each carrier on the basis of operator information obtained from an AT command or the like.

In the present embodiment, a BT-connected mobile phone has been described as an example of the external-network connection device. However, mobile phones in other connection modes such as a USE and a WLAN are also applicable.

As described above, the present embodiment makes it possible for an AP to change an external-network connection device connected to the AP in accordance with a WLAN STA connected to the AP. Therefore, in addition to the effects obtained from the first embodiment, the present embodiment can restrict use of a BT device by a non-permitted WLAN STA, and thus can prevent unintended billing, a connection made by a WLAN STA when used by another person, and other circumstances.

Third Embodiment

In the present embodiment, a case is described where there is no connection history between the AP1and a BT device, and nothing is registered in the connection history DB14. Parts different from those in the first embodiment are described.

The configuration of the communication network and the configuration of the AS1according to the present invention are identical to those illustrated inFIG. 1and

Next, a network connection process in the AP1according to the present embodiment is described.FIG. 8is a sequence diagram illustrating the network connection process according to the present embodiment. In the initial state illustrated inFIG. 8, it is assumed, as described previously, that there is no connection history between the AP1and the BTs3and4, and nothing is registered in the connection history DB14.

The processes at Steps S301to S303are the same as the processes at Steps S101to S103in the first embodiment.

In the AP1having established a connection to the WLAN STA2, the connection management unit13confirms whether there is a connection to an external network. Upon confirming that there is no connection, further searching the connection history DB14, and consequently confirming that a BT device is not registered, the connection management unit13suspends a request pending from the WLAN STA2to an external network (Step S304).

The WLAN STA2starts-up a browser in order to connect to an external network and transmits a request message to the AP1(Step S305). The AP1determines whether the request message is a request from the browser on the basis of the packet TCP header information and the like.

In the AP1that has received the request from the WLAN STA2, the connection management unit13temporarily suspends the request from the WLAN STA2and starts inquiring about a peripheral BT device via the BT control unit12(Step S306).

Upon finishing the ST-device inquiry, the connection management unit13in the AP1converts the obtained BT-device inquiry results into a form that can be displayed in a Web browser and returns the converted inquiry results as a reply message to the WLAN STA2via the WLAN control unit11(Step S307). The WLAN STA2displays the BT-device inquiry results in the browser.

The WLAN STA2selects its desired connecting BT device (the BT3in this example) from the list of BT devices displayed by the browser (Step S308).

The connection management unit13in the AP1performs a pairing process with the BT device (the BT3) selected at Step S308. When it is necessary to input and display a PIN code, the connection management unit13converts the PIN code into a form that can be displayed in the Web browser and transmits the converted PIN code to the WLAN STA2via the WLAN control unit11. Therefore, the connection management unit13in the AP1displays this PIN code in the browser of the WLAN STA2and instructs the inputting process. The connection management unit13in the AP1uses the obtained information to continue the pairing (Step S309). The basic operations of the pairing are based on the “Bluetooth, “Specification of Bluetooth System Covered Core Package Version: 4.0”, 30 Jun. 2010”. However, the version of Bluetooth and the like are not specifically limited thereto as long as being able to connect to the BT3illustrated inFIG. 8.

In the AP1, the connection management unit13executes a profile connection with the BT3connected thereto via the BT control unit12(Step S310).

The AP1connects to the WLAN STA2and to the ST3capable of communicating with an external network and is therefore capable of providing communication with the external network via its own apparatus and the BT3to the WLAN STA2. The WLAN STA2can communicate with the external network via the communication apparatus and the BT3.

In the present embodiment, at Step S307, a WLAN STA device displays all the BT inquiry results. However, the WLAN STA device can obtain BT-device support profile information according to the SDP (Service Discovery Protocol) and can display only a BT device that supports the DUN or PAN. Further, in a case where another profile such as an HFP (Hands Free Profile) has been already connected to a BT device, and thus simultaneous connection to the DUN or PAN cannot be provided, the WLAN STA device is still capable of displaying a message in the browser. In this case, the AP1notifies the WLAN STA device that simultaneous connections cannot be provided.

Note that the AP1has stored in advance in a DB the APN setting and other information required for connecting to an external network, which also makes it possible to automatically perform the APN setting suitable for each carrier on the basis of operator information obtained from an AT command or the like.

In the present embodiment, a BT-connected mobile phone has been described as an example of the external-network connection device. However, similarly to the first embodiment, this is also applicable to WLAN-connected devices and other devices in which input for device selection, a PIN code input or the like at the time of authentication are needed.

In the present embodiment, the AP1transmits and receives information via the browser of the WLAN STA device. However, the present invention is not limited thereto. Using a specific application or using a sound input from a speaker or a microphone is also possible.

As described above, according to the present embodiment, in the network configuration in which an AP connects to an external network via another device, when the AP connects to an external-network connection device that is not registered in the connection history, information required for the authentication of the connection of the AP and the external-network connection device is displayed in a browser of a WLAN STA. Therefore, a user can continue the connection process by operating the WLAN STA without the need of an AP operation.

When BT-device inquiry results are displayed when connecting to a BT device, filtering of these results using profile information in the AP can prevent a BT device, which does not have a function of connecting to an external network, from being displayed to a user.

INDUSTRIAL APPLICABILITY

As described above, the communication apparatus according to the present invention is useful for wireless communication, and it is particularly suitable for an apparatus capable of providing a connection to an external network.

REFERENCE SIGNS LIST