[K12OSN] Router mystery

["Terrell Prudé, Jr."]

Les Mikesell wrote:

>On Sun, 2005-03-06 at 08:17, Ken Johnson wrote:
>  
>
>>I'm a newbie  trying to test k12LTSP on my home network that consists of:
>>
>>cable modem --->Netgear MR814 Router--->PCs
>>
>>When I connect the k12LTSP server  (eth1) to the router it doesn't see
>>the Internet.
>>
>>When I connect  the k12LTSP server  (eth1) directly to the cable modem
>>it DOES see the internet.  Why?
>>    
>>
>
>This should work if the k12ltsp box is getting settings via DHCP in
>both cases.  One possible problem would be if the router is
>set to NAT to 192.168.0.0/24 and the k12ltsp box is also using
>192.168.0.0/24 on eth0.  You can see this with:
>ifconfig -a
>after getting a dhcp address from the router.  The two interfaces
>much have different subnet numbers.  You can change either one
>but if you going to test k12ltsp and reinstall often you might
>want to leave the default there and change the one on the
>router.  The router should have a web interface for this and
>any other number in the 3rd position (192.168.x.1 for the router,
>192.168.x.0/24 - netmask 255.255.255.0 for the net) will work.
>
>  
>
True; I ran into this before, here at home.  My router NATs to 
192.168.0.0/24, which is why I started using 172.16.0.0/24 on the 
K12LTSP server.  You can also tell your router to start NATing to 
something other than 192.168.0.0/24 (say, 172.16.20.0/24, or 
192.168.199.0/24, for example).

The other thing you want to make sure of is that you reboot your cable 
modem after plugging something new into it.  Every cable modem that I've 
ever touched (it's been hundreds) seems to lock onto the first MAC 
address that it sees, e. g. your PC.  If you plug anything else into it 
afterward, the cable modem will say, "Oops, I'm 'married' to someone 
else, sorry" and will not bridge traffic.  The solution is to simply 
power-cycle the cable modem after you plug something different (say, a 
router) into it.  I've run Netgears, Linksys's, and Ciscos of various 
types off of cable modems, and all work great.

--TP
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