Hello.
I have recently been trying to mount a home automation station on a raspberry.
I need to communicate with the station via SMS. To do this, I order a 3G dongle (UMTS / GSM / 3G / 4G etc ...) operating on the country's network (verified frequencies). I connect to the network via wifi. But when connecting the 3G dongle, here I am blocked on access to Wifi.
My first question is therefore: is this normal?
And my second is: is it possible to make both work in parallel?
Thx all
It depends on the exact use case or requirement and type of device in hand.
In general, the device will choose/use the wireless connection with better connectivity strength as per its design/specification and also it depends on the support at device.
In case you have the option of WiFi Hotspot tethering enabled, it is possible that most of the devices nowadays allow you to use 3G for the internet communication and at the same time, it allows WiFi hotspot sharing with the help of WiFi from your device.
Also, few devices have support for file sharing between device to device whereby they provide support for wifi direct and wifi sharing while 3G connectivity with internet is still fine. Few devices from Samsung, support an application called "Download Booster" that allows your device to download files using WiFi connection and a mobile data connection simultaneously.
Few devices from Apple starting iOS 7 introduced Multipath TCP enables users to have their streaming music to never get interrupted while on high mobility or in trains and other vehicles with changing connectivity whereby no manual switch from between WiFi and Cellular is required in which case, the device shall stay connected over both cellular and WiFi simultaneously and whenever the WiFi connection fails, the cellular connection shall continue with streaming operation without any interruption.
There is also a app called 'Speedify' in android that uses channel bonding technology to combine multiple Internet connections together for increased throughput & redundancy and thereby it can merge WiFi and Cellular connection simultaneously. Here, a Speedify client software is used to establish a connection to a Speed Server in cloud that acts as a middleman between you and the rest of the internet. The Speedify client software then works together with Speed Server to distribute your internet traffic and deliver the combined speed of all available internet connections.
Related
So I my ISP assigns local private IP address to devices on the network, I found that by checking the IP address assigned to my phone's ccmni0 interface which I believe is the one used to connect to the network.
And so I tried sending a message to my other phone (which uses a SIM card from the same network provider as the other, so I assumed they are on the same network) using the local IP assigned to it. I was expecting to receive the message on the device but didn't, that's why I suspect the reason might be because they use different cellular technology (one 3G and the other 4G).
Please tell me if my suspicion is true or not. And guide me if I have done anything wrong.
With WiFi you can control which device can connect to your WiFi device by managing which devices know the SSID+wpa2 couple. Is it possible to do the same thing in bluetooth?
In other words, I want to be able to do with Bluetooth what I do in WiFi by connecting two devices with a default SSID+wpa2, once the connection is established, automatically generate new SSID+wpa2 and share this couple to control which others devices can connect.
I develop a app which discovers a network topology and draw it programmaticly with java and SNMP4j
I send CDP and LLDP requests to devices and analyze result of this. However there are devices which has not support CDP or LLDP(like Access Point) therefor I cannot discover it. I must show it as unkown device.
Thanks to CDP and LLDP I know which device is on which port. To understand unknown device is on which port,
I need a oid to learn up and down ports of the Switch with SNMP or another method.
I use SNMP4J
The table dot1dTpFdbTable (1.3.6.1.2.1.17.4.3) shows which MAC addresses can be reached on which ports.
Two things to watch out for: it is not supported by all devices and it does not only list the connected devices but also everything connected to those devices.
I read a lot about WiFi sensors being used to track smart phones in Retail environment. The location triangulation is done on basis that a smart phone has its WiFi turned ON, be it in connected or unconnected state.
Case 1 : WiFi turned ON but unconnected
Why should a smart phone which has its WiFi turned ON need to transmit the packets, unless the user 'scans' for nearby WiFi networks?
Case 2 : WiFi turned ON and connected
Why should a smart phone transmit any packets, unless the user is browsing the net?
In both the above cases, there is a high chance that most of the time the WiFi device does not send any packet, which means none of the WiFi sensors detect it. If that is true, then the whole idea behind WiFi sensor based triangulation in Retail goes for toss, clearly with so many companies working on this, I must be wrong. Please answer with more than a yes or no, as to which packets are generally sent in both the above scenarios.
If wifi is turned on it will periodically search for new networks. This happens even if you are already connected to one, as it allows the device to connect to a 'better' network, if available.
Scanning/network discovery can be done in two ways. First is passive when a device listens to surrounding access point's (AP) beacon frames. These are basically advertisements for their network. The second method is called active. This is the most likely explanation of how the technology you mentioned works. Active scanning is when the device sends out a probe frame asking for available APs. These are generally ones that you have associated with previously, e.g. Your home network. These probes can be listened to from nearby 802.11 (wifi) devices, therefore tracking you.
Active and passive scanning
801.11 frames
As mentioned in #AndrewLeeming answer, one of the causes for data transmission data is scanning.
It's not necessary but normally it will be performed to find a network to connect to (or a better network in case of already connected). Active scanning can be turned off for power saving reasons. Passive scanning doesn't involve transmissions, so it's irrelevant to this question.
However, the most important reason for WiFi devices to transmit packets while connected is to let the AP know that the client is still available. Otherwise the AP will drop the link after a certain period of time without activity. Additionally, the clients might be in power save mode and instruct the AP not to transmit data to them. From time to time the client will inquire the AP to see if there are any pending packets for it.
I set up an Access Point using the following command:
netsh wlan set hostednetwork mode=allow ssid=DotA key=pass keyUsage=persistent
I am eager to know what topology (star, mesh etc.) does it use, so I may use it optimally as per my needs.
P.S.: I did post my question on SuperUser.com but got no response.
Hoping to be lucky here. :)
Microsoft says that
The wireless Hosted Network is a new WLAN feature supported on Windows 7 and on Windows Server 2008 R2 with the Wireless LAN Service installed. This feature implements two major functions:
The virtualization of a physical wireless adapter into more than one virtual wireless adapter sometimes referred to as Virtual Wi-Fi.
software-based wireless access point (AP) sometimes referred to as a SoftAP that uses a designated virtual wireless adapter.
and
With this feature, a Windows computer can use a single physical wireless adapter to connect as a client to a hardware access point (AP), while at the same time acting as a software AP allowing other wireless-capable devices to connect to it.
As it is on the AP mode (or managed mode) when you want to connect other wireless device to be connected to your laptop as a client (phone, laptop, tablet, etc.) so that it would be a star topology.
But when it connects to an Access Point like a WiFi router, then it will act as a client (or station adapter), then it would be a start topology again.
Mesh topology are commonly used on ad-hoc wlan mode.