Handling multiple devices

[jamesonuk]

I setup two of these to test their use and also to test TREL.

I believe

esp-thread-br/examples/basic_thread_border_router/main/esp_ot_br.c

Line 98 in b8bffd2

ESP_ERROR_CHECK(mdns_hostname_set("esp-ot-br"));

gives them a static mdns name which has lead to some confusion and conflicts.

would this be better to use the MAC address or some other identifier in the name here or is there a better way to do this?

AI has suggested setting CONFIG_OPENTHREAD_BORDER_AGENT_MESHCOP_SERVICE_BASE_NAME to match the one set above.

It also mentioned that mdns_instance_name_set should be used to set a display name.

Any advice appreciated and is it worth including any of this in the example code?

[kepstin]

The example code is intended to be used as a base for commercial thread border router products to the best of my understanding, so it should provide a "best practices" example of how to set up the hostname for mdns.

I would recommend using (part of) the mac address in the hostname in order to make it unique. A fairly common practice that i've seen in commercial devices is to take the last two bytes of the mac address in hex and append them to the hostname. It's unlikely that someone will have two devices from the same vendor where the mac address matches in the last 2 bytes. Alternately, use the whole mac address in hex with a short (~3 letter) prefix.

The thread border router example code already uses the mac address to make the wifi AP name unique for performing setup over wifi.

[zwx1995esp]

Hi @jamesonuk and @kepstin

The TBR example is intended to demonstrate how to run a FreeRTOS-based Thread Border Router on an ESP chip, with the primary focus on Thread features. Regarding the host name, this is typically application-specific, and you are free to define your own TBR host name.

As for your comment that it “gives them a static mDNS name which has led to some confusion and conflicts,” I believe mDNS includes a mechanism to automatically resolve name conflicts. Please see: https://github.com/espressif/esp-protocols/blob/master/components/mdns/mdns_receive.c#L136C11-L136C77 So even if multiple TBRs are set with the same host name within the same local network, there should be no conflicts.

[jamesonuk]

I realise this is an example but I would have thought it is better to make it realistic.

The issue comes in that the host is set to esp-ot-br and if that is taken it will end up with esp-ot-br-1. If you then unplug the devices and connect them back in the reverse order then they swap so there is no way to identify which is which. I also had a few other bits of confusion around not being able to easily tell which device was which.

I have set this up for testing TREL and redundancy so I am testing that it does fail over and also that it uses the ethernet backbone to connect to devices that aren't accessible over Thread radio. As the hostname can change this has caused me some confusion. Including some or all of the MAC address would make it unique and avoid all these issues.