What "protocol" services like Sonos or Chromecast use to communicate between devices over the same WiFi? In particualr, how do those devices make themselves discoverable and how do they "fish" for incoming communication?
WiFi Communication – How Do Devices Communicate Over a WiFi Network?
ieee 802.11wireless
Related Solutions
How can my wifi board detect wireless networks that are in range?
Your client has a radio which listens to the wifi 802.11 frequencies for the country configured in the radio.
What protocol is used to communicate with the devices in the area to announce a wifi AP?
Wifi APs are configured with an SSID; those SSIDs are known via beacon frames; by default beacon frames are sent every 102.4 milliseconds.
The beacon frame format includes an SSID field, and the beacon interval.
The radio in your AP is configured for a specific channel. Those beacon frames are transmitted on the AP's channel.
Does every router transmit on its own frequency and my wifi board scans "every" frequency to detect one?
Every wireless AP can select from a pre-defined list of wireless channels, and it chooses one channel to announce the SSID. Your wifi client constantly walks (or scans through) all those channels to figure out which SSIDs are available.
On SonicWALLS, in version 5.x (and 6 too, I imagine) this is known as "Interface Trust". To adjust this setting, go to Network -> Zones and check the box to "Allow Interface Trust" to resolve this issue.
I will caution you however that if you are using the WLAN zone which has interface trust disabled by default, and you are using a SonicPoint with version 5.x you are doing it wrong. The wireless configuration of SonicPoints is extremely arduous and I cannot disrecommend this product enough. If you can return these, do. They are a major headache. I love their firewall, but hate their SonicPoints.
To properly configure them, the SonicPoints should be the only thing in the WLAN zone which should be on an untagged VLAN. You should then create another zone (with interface trust enabled). You then need to go to Network -> Interfaces and click "Add Interface" and create an interface with a VLAN tag other than 1 with a parent interface of whatever the SonicPoint is plugged into and you need to select your newly created zone.
Next, navigate to SonicPoint -> Virtual Access Point and create a Virtual Access Point Group (VAP group) and then create a Virtual Access point. The Virtual Access Point (VAP) needs to be set to the same VLAN tag you used earlier. Then you need to edit the VAP Group and add the VAP to it. Finally, you are ready to go to SonicPoint -> SonicPoints and edit the SonicPoint in the middle section. You then can assign the VAP group to the WAP.
You will also need to ensure that the WAP is either plugged directly into the SonicWALL or that you have a switch that supports VLAN tagging. If you go the switch route, you need to have the untagged VLAN assigned to the port you connect the WAP(s) to and tag or trunk each of the VLANs on the port on the switch using the same VLAN tag/number you used on the SonicWALL - otherwise you will run into issues. If you need to connect more than one WAP directly to the SonicWALL, you can use PortShield groups to have 2 ports on the same WLAN zone.
If you do not do this, you will find weird issues like being unable to talk to the other computers on the network, but getting internet access or getting spotty internet access which will work great for awhile and then drop out all of the sudden inexplicably.
Finally, you should note that you will need to configure firewall rules between the zone you created and the LAN zone in order to talk to your wired printer and other devices on the LAN. You should also note that you will be unable to discover that printer automagically using Windows because the WAP is not on the same zone as the printer (no matter what you do) and that Bonjour (if you use a mac) will not discover properly unless you configure multicasting and adjust some other specialized settings in an advanced configuration page and configure mDNS in IP Helper. You may also need to make some special adjustments for IPv6. You can however specify the IP address manually to print to the printer.
Best Answer
At layer-1 and layer-2, Wi-Fi is used instead of a wired protocol like ethernet.
Above that, the layer-3 protocol (IPv4, IPv6, etc.) will be the same, as will the layer-4 protocol (TCP, UDP, etc.).
Protocols above layer-4 are explicitly off-topic here but they will be the same as used on a wired network.
The whole idea behind the network stack is that each layer in the stack is independent of the other layers in the stack. For instance, IPv4 happily runs on many different layer-2 protocols (ethernet, Wi-Fi, PPP, frame relay, HDLC, etc.), and it doesn't know or care which layer-2 protocol carries it. Layer-2 protocols, such as ethernet and Wi-Fi, can carry any number of layer-3 protocols (IPv4, IPX, IPv6 AppleTalk, etc.), and they don't care which layer-3 protocol they are carrying.
As far as an application is concerned, nothing has changed, because the application is oblivious to the lower-level protocols being used.