[lwip-users] Question regarding mdns responder

[Axel Lin]

Hi,

I have 2 devices running lwip with mdns responder enabled.
My mdns setup code:

mdns_resp_init();
mdns_resp_add_netif(my_netif, "BGW", 255);
// the name is "BGW [xx:xx:xx:xx:xx]" (xx:xx... is MAC address)
// my_get_txt just call mdns_resp_add_service_txtitem(service, ip_str,
strlen(ip_str)); to dislay my current ip (for verification)
mdns_resp_add_service(my_netif, name, "_http", DNSSD_PROTO_TCP, 80,
120, my_get_txt, NULL);

On my Linux laptop, execute avahi-discover to find the devices:

$ avahi-discover
Browsing domain 'local' on -1.-1 ...
Browsing for services of type '_http._tcp' in domain 'local' on 3.0 ...
Found service 'BGW [AC:83:F3:A0:41:C0]' of type '_http._tcp' in domain
'local' on 3.0.
Found service 'BGW [AC:83:F3:A0:42:20]' of type '_http._tcp' in domain
'local' on 3.0.
Service data for service 'BGW [AC:83:F3:A0:42:20]' of type
'_http._tcp' in domain 'local' on 3.0:
        Host BGW.local (192.168.0.102), port 80, TXT data: ['IP=192.168.0.100']
Service data for service 'BGW [AC:83:F3:A0:41:C0]' of type
'_http._tcp' in domain 'local' on 3.0:
        Host BGW.local (192.168.0.102), port 80, TXT data: ['IP=192.168.0.102']

$ avahi-browse -a --resolve
+ wlp3s0 IPv4 BGW [AC:83:F3:A0:42:20]                       Web Site
          local
= wlp3s0 IPv4 BGW [AC:83:F3:A0:42:20]                       Web Site
          local
   hostname = [BGW.local]
   address = [192.168.0.102]
   port = [80]
   txt = ["IP=192.168.0.100"]
+ wlp3s0 IPv4 BGW [AC:83:F3:A0:41:C0]                       Web Site
          local
= wlp3s0 IPv4 BGW [AC:83:F3:A0:41:C0]                       Web Site
          local
   hostname = [BGW.local]
   address = [192.168.0.102]
   port = [80]
   txt = ["IP=192.168.0.102"]

My question is:
Why both device display address : 192.168.0.102?
And sometimes both devices show "BGW.local (192.168.0.100)".
i.e. When I have multiple devices running on the local network, I
cannot find the ip address of each device.

Thanks,
Axel