Two Ethernet coexist discussion

[ruei_chang]

Hello everyone, 

     I have been researching how to make two ethernets coexist.  I know the standard Android only have one ethernet.

So I tried to modify fsl's ethernet app and frameworks. and finally, I can have eth0 and eth1 working at the same time.

   To ping different IPs in eth0 and eth1 is working. So I thought I had completed the two LAN on i.MX6. But unfortunately...there is a problem still there.

   I found no matter which one I enable first, the DNS of the first one will be disabled as long as I enable another ethernet.

   But meanwhile, it is no problem to ping the IP in these two ethernets.

   I don't know if I missed something. Does anyone of you know how to let the first DNS keep working even enable another ethernet?  Thanks in advance.

My platform is i.MX6 duallite with Android 6, kernel 4.1.15.  

[b36401]

You can have only one DNS service for the applications running in the OS.
If you need to "combine" name spaces of eth0 and eth1 uplink DNS servers you need to configure your oun DNS server that will be asking these external ones for the resolving.
However it is quite complicated task and it is recommended to use only one DNS server.
For examply you can check with network is available at the moment and set exact DNS server in the configuration in the real time.

Have a great day,
Victor

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[ruei_chang]

Thank you, Victor. 

Absolutely, let two DNSs coexist in Android is a complicated task. So this will be a challenge for me.

I had found there is a netd service which is network management to set up the network configurations even the DNS.

Maybe I need to check out this service for DNS configuration. 

Thank you, Victor. I'll take your advice and figure out the best way to fix up the problem.