[ale] question about ganging routers together

[David Tomaschik]

On 08/01/2011 01:45 PM, Ron Frazier wrote:
> Hi guys.  My schedule only lets me get on the list intermittently.  It 
> takes a bit of time to keep up with all the postings.  I'm going to try 
> to catch up on the old posts, including any which may have been old 
> replies to my messages since I was last on a couple of weeks ago.  In 
> any case, I have a question about ganging routers together.  I hope I 
> can explain this in a way that makes sense.
>
> I have my main router 192.168.83.1 (LAN address) which connects to the 
> internet.  I wanted to test another wireless router 192.168.79.1 (LAN 
> address).  Both routers are set up to provide DHCP service.  I plugged 
> router 79 into a LAN port on router 83.  I meant to run the cable from 
> the WAN port on router 79 to the LAN port on router 83.  However, I 
> actually ran the cable from LAN to LAN port by mistake.  I have 
> subsequently fixed the mistake, but what they did really confused me, so 
> I hope some of you can shed some light on it.  While the cables were 
> wrong, I logged into 79 wirelessly, and proceeded to access the 
> internet, which worked just fine.  I had expected to get an IP address 
> from router 79 which would be something like 192.168.79.2, etc.  
> However, when I tried to access the control panel for 79, I could not.  
> I ultimately found out that my IP address was coming from 83, and was 
> something like 192.168.83.2, etc.  I thought, surely I'm not wirelessly 
> connected to 83.  I verified again that I was connected to 79.  It took 
> me quite a while to figure out what was wrong.  Once I fixed the cables, 
> everything was fine, and I got my IP from 79 as I should, and I was able 
> to access it's control panel.  I'm just wondering if anyone can tell me 
> what was happening, and why I wasn't getting an IP address from 79 even 
> though I was logged wirelessly into it.  For that matter, I'm not really 
> sure how my internet connection was working at all with it wired that 
> way.  Any ideas are appreciated.
>
> Sincerely,
>
> Ron
>
You'd effectively bridged the two routers into one network.  Both
wireless networks, both LAN networks, and the "LAN" side of the
controller chips of both routers were all on one physical LAN.  So when
your system requested an IP address (DHCP DISCOVER), most likely both
routers responded with a DHCP response.  If the computer got the
response from the '83' router first, that's the IP it took.  There's a
million reasons why one would get a response from the other router
first, including differences in firmware, chipset, etc.

David