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Devices connecting to the Wlan Box 2 with no IP adresses

pa.friederich
Level 2
1 of 6

Hi everyone,

 

Infrastructure:

I recently moved into a 3-stories house and I purchased 2 Wlan-Box 2 to extend the coverage of the WiFi from my Internet Box 2.

 

I installed some smart switches from Allerco Robotics, also known as Shelly.

 

Problem encountered:

When monitoring my network from the web portal of the Internet Box, I noticed some unusual connections. I have mostly 10 devices, outside of the smart switches, that are connected to the Internet with a WiFi connection, and it is easy to spot them.

 

This is not someone trying to hack my network as I have rule out the suspect or rather the suspects.

 

The unusual connections are all linked to these smart switches. The Shelly connects to the network only on the 2.4 Ghz band. It appears usually with a name that is PC-XXX with a defined MAC address. Then, I noticed that a lot of other clients start to connect to the same access point, with a MAC address starting with 5E:BB:00:... I checked wether it was something linked to a specific manufacturer, but it doesn't. Under the IP address field, there is "Device doesn't need an IP address". With one Shelly connected to the Wlan-Box 2, there are about 23 to 25 connected device at the same time. It varies continuously when the Shelly is connected, new devices connecting with a name PC-XXX + 1 and older ones disconnecting from it.

 

Network TopologyNetwork Topology

 

Device ListDevice List

 

Strangely enough, these devices don't appear on the Home App.

Moreover, when the Shellies are connected directly to the Internet Box, there is no such devices appearing.

 

What I tried so far:

  • I made some modifications to the Internet Box parameters without any luck. Static IP either on the router or the smart switch, WiFi 6 deactivation. I think I changed nearly all the settings without getting a different result.
  • I reset every Wlan Box and Internet Box and also flashed older firmware without getting a different result.
  • I tried to create a guest WiFi and move the Shellies on it and it seemed that there was no more ghost devices, but that is not really practicable, as I have to be one the same network to interact with them.
  • I read that sometimes WiFi repeater give mixed results with IoT devices, so I used a long cable to plug the Wlan-Box as an access point, but there was no noticeable difference.
  • I flashed an alternate firmware on the Shellies with native HomeKit support and in this case, there are no ghost devices. This is an open-source firmware and the capabilities, while promising, are still way behind the official firmware. This is definitely not an ideal solution for me.
  • I flashed older firmware versions of the official firmware, without getting a different behaviour.

It may be only a  display glitch in the Internet Box web portal, as it does not appear with the Home App.

Alternatively, this is maybe linked to the Wlan Box, because I cannot reproduce the problem with the Internet Box.

I also contacted the manufacturer's support to see if the problem is on their side.

 

Question:

 

Has any of you experienced similar devices without IP adresses on the network ? Did you find a solution to get rid of them ?

 

Any help would be appreciated

Edited
ACCEPTED SOLUTION 1

Accepted Solutions
pa.friederich
Level 2
6 of 6

I wanted to give a quick update. 

I upgraded the WLAN-Box 2 firmware with the current Beta (11-03-17) and the problem is gone. When the smart switches are connected to it, there are no more clients with no IP addresses appearing in the web portal.

 

This was most probably a bug in the firmware, that was fixed in the latest Beta. I will see if the problem is solved when the firmware is officially released.

5 Comments 5
Black Mamba
Super User
2 of 6

@pa.friederich thanks for the contribution

what is the question raised please?

pa.friederich
Level 2
3 of 6

Hi @Black Mamba ,

 

I edited my post to clarify my question. Is it clearer now ?

SkyBeam
Level 4
4 of 6

It is actually quite normal to have devices which do not have an IP. Each device will first connect to the network on Layer 2 (MAC). If it uses Layer 3 communication based on IP it will request an IP by sending a DHCP request usually.

But as said this is not mandatory. There are devices which use other protocols than IP to communicate. For example some home automation devices will entirely use Layer 2 (MAC) communication. Sending Broadcast messages in the network to discover each other.

 

Those devices are listed by the Internet Box with the remark that the device does not need an IP.

 

The way they are discovered is simple: Each device on the network will allow inbound packets either sent to the MAC address of the device or to a broadcast MAC (actually broadcasted in the whole LAN to every device). If the Internet Box is seeing a packet sent to a broadcast MAC it will process it and add the device to the device list if it's a new device. If the package it received is not containing any IP header then the device is listed as a non-IP device (device does not need an IP). If the device later on requests an IP via DHCP and sends IP packets to the router it will add this IP information. But if the device is using any other protocol (like IPX, SCCP) there is simply no IP address associated to the device. Of course this does not mean the device cannot communicate. It will just not use IP for communication.

 

For example many "smart-managed" switches also do not have an IP address and communicate with specific discovery protocols on the LAN without using IP addressing.

 

 

The only thing which is not completely clear to me is why the same MAC address (same device) appearing multiple times on your WiFi repeater. But potentially this is "just" a display glitch in the firmware so it does not overwrite/combine the MAC entry from a newly discovered device but actually adds a new entry each time it sees packets from this device. I don't think this should cause any issues though. It might however indidcate that the device might frequently re-connect to the WiFi network rather than staying connected. Depending on your WiFi setup the device might also change between access points and roam between the Wireless Box 2 and your Internet Box WLAN.

 

 

Now I am entering some guessing...

Your Wireless Box seems to be connected via 5GHz WiFi. Unfortunately this is not an ideal setup. Your clients (the smart home switches) might also be moved around the nodes in the mesh. Moreover as due to the way a mesh works the broadcast messages (MAC broadcast) will have to be forwarded across all nodes in the mesh. Broadcast is usually a very bad thing in WiFi mesh networks.

So it might be possible that your Wireless Boxes will see the MAC address from the broadcast discovery messages passed on within the network multiple times.

My recommendation as usual would be to connect the Wireless Boxes via Ethernet Cable to the Internet Box and use them as simple access points rather than in WiFi Mesh setup.

 

The issue you are seeing might be just "cosmetical" without  having negative impact on functionality but for sure your setup is inefficient in regards of mesh setup and therefore inefficient in wireless spectrum usage and sepcifically it is inefficient handling broadcast messages in particular (general mesh issue).

pa.friederich
Level 2
5 of 6

Hello @SkyBeam,

 

Thank you for our detailed explanation. This is indeed very interesting.

The smart switches are only working with WiFi, and only the 2.4 Ghz network. Even if there is a 5 Ghz network, they don't see it. 

To be sure, I connected the Wlan-Box with an ethernet cable and disabled the 5 Ghz network. There is no change at all. Even separating the networks to avoid WLAN steering has no effect on the displayed devices.

 

I made some more tests with Wireshark to see what was happening on my network.

Indeed the packet that are sent on the network when the smart switch is connected do not contain any IP address. The address is always changing but the destination address is always the same.

The protocol that is used is unknown. I don't know if it is just a filter that is not set correctly in the firmware of the internet box, to avoid registering them as clients.

 

It is indeed only "cosmetical", and has no impact on the performance of the equipment, and except for that, I have nothing to complain about my setup. I was aware that it was inefficient in terms of mesh network, but I cannot change the wiring of the house as I am only renting the place and it would be too costly to do it.

 

Wireshark - incriminating frameWireshark - incriminating frame

 

 

pa.friederich
Level 2
6 of 6

I wanted to give a quick update. 

I upgraded the WLAN-Box 2 firmware with the current Beta (11-03-17) and the problem is gone. When the smart switches are connected to it, there are no more clients with no IP addresses appearing in the web portal.

 

This was most probably a bug in the firmware, that was fixed in the latest Beta. I will see if the problem is solved when the firmware is officially released.

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