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-   -   Ethernet & Wifi address conflict (Basic question) (http://www.linuxquestions.org/questions/showthread.php?t=4175458249)

RogueWarrior65 04-15-2013 09:39 PM

Ethernet & Wifi address conflict (Basic question)
 
I have an SBC with ethernet and wifi devices. If, for example, I assign the ethernet device to 192.168.15.200 and the wifi to 192.168.15.150 both with netmask 255.255.255.0, whichever device was brought up first works but the second one doesn't e.g. I can ping the first address/device from another computer on the network but not the second. If I ifconfig down the first device, I can then ping the second. What am I not configuring correctly?

phans 04-16-2013 08:30 PM

Please provide more info. Is one device a router and the other a wireless router (access point)? Or are both devices clients, such as a wired desktop computer and a wifi laptop or something?

RogueWarrior65 04-17-2013 07:59 AM

Okay, I have an Airport Time Machine as my router, a laptop, and a TS-7552 which has both ethernet and 802.11g on it. The laptop and the 7552 are clients.

polypagan 04-17-2013 09:55 AM

It's challenging to route packets to the same subnet via two adapters.
Is there something special about 292.168.15.x?
Try making one adapter 192.168.16.x and that should work.

Is there a reason you're not letting DHCP sort this?

Study the output of ../sbin/route command.

RogueWarrior65 04-18-2013 09:07 AM

Hmm...okay, I'll mess around with the addresses. Shouldn't I also have to change the netmask to 255.255.0.0 to get that different subnet to work?
As for not using DHCP, I do that on my laptop and the Airport has it running but the SBCs are faceless so I would have no clue what the address might be each time I boot it and no way of figuring it out without plugging in the serial console cable.

polypagan 04-19-2013 10:58 AM

netmask 255:255:255:0 is correct for class C IPv4 addresses (private addresses) like 192.168.x.x

Those first two bytes define the address class, the third defines the subnet within the class and the fourth byte defines the host (0..254), so all three bytes effectively define the subnet (the one's in the mask, 255=0xff).

Don't know about Airport. Some devices allow you to associate fixed IP's with physical (MAC) addresses (so-called "Static DHCP", an oxymoron). I believe all Airports will allow you to interrogate the DHCP table to learn what address has been assigned.

And, that might not work for you.

If I understand your topology correctly (not at all sure I do), what I'm suggesting may not be possible. If both interfaces need to connect to the Airport, they will need to be on the same subnet as its LAN... You may need more advanced routing on the SBC...


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