Setup: where to plug the router?

[Souli]

Hey,
I am moving away from my normal DSL internet to a 3G mobile modem and need help how to setup the routers.

My 3g modem is plugged into a TP-Link MR3220. On the TP-Link I wanna turn off all the features it is only there to provide the internet connection.
As my main router I use a Apple Airport Extreme Base Station and an Airport Express to extend my WLAN.

So now my question is do I plug the TP-Link into a LAN port on the AEBS or the WAN port? From my understanding it should be the WAN port since the AEBS provides the firewall and all the other important features and the TP-Link functions as a modem. Is that correct?

 

[overdrive31]

You may need to change the default subnet on either router, I think they both use 192.168.1.1(the Airport Extreme may use 10.0.1.1, 172.16.1.1, or 192.168.1.1), and yes plugging the TP-link into the WAN port of the Airport Extreme is correct. Looking over the MR3220 emulator, doesn't seem you can bridge the 3g modem to the Airport, you will have to either leave DHCP enabled or disable DHCP and use static, and you should put the Airport in the DMZ of the MR3220.

 

[Souli]

thanks for the reply.
Does it matter if I turn off the firewall and other features on the TP-link or is it useless if I use a DMZ to forward the traffic to the AEBS?

edit: I just finished setting everything up but the AEBS gives me a warning message "Double NAT". Is that a problem? If it is how do I fix it?

Setup is like that now:
TP-Link IP 192.168.2.1 (DMZ for 192.168.2.2) DHCP off
AEBS: WAN Port (static) 192.168.2.2
LAN IP 192.168.1.1 DHCP + NAT on

Internet seems to work since I wrote this post using that setup now.

 

[overdrive31]

Yeah, the TP-Link doesn't allow you to bridge the 3g modem to another device, so double NAT is unavoidable. But, it is mitigated mostly by the AEBS being in the TP-Link's DMZ and even if the firewall were enabled on the TP-Link, devices in the DMZ will bypass such.

 

[JohnPierce]

3G TP LINK 3420 to Time Capsule

Great discussion, I will be looking at this config now, does this solution work? do the IP address range needs to be the same in the TP Link Router and Time Capsule, supposed to use bridge mode, not very elegant Appreciate all help and guidance

 

[coxhaus]

Why not just connect the 3g modem directly to the Apple Airport Extreme Base Station direct using the WAN port? It sounds like if you go direct you will avoid using double NAT.

 

[JohnPierce]

The 3G modem is actually a Dongle on USB, that is where the TP Link MR3420 fits in.

Do you have any experience on port forwarding via a DMZ setup

Regards

John

 

[stevech]

I use my USB modem in my laptop and occasionally in my Cradlepoint router which has extensive cellular support.

 

[Dreamslacker]

Is there any reason to use the Airport as a router over the TP-Link?

If not, just connect the AEBS via it's WAN port to the TP-Link and set it to bridged mode. Ditto for the AE unit (or use extend network if using wifi link).

You just need to disable the wifi on the TP-Link if you don't need it.

 

[Samir]

The 3G modem is actually a Dongle on USB, that is where the TP Link MR3420 fits in.

Do you have any experience on port forwarding via a DMZ setup

Regards

John

This setup is actually quite simple. The hardest part is to make sure both routers do not have IP addresses in the same range. Ie, use 192.168.1.x for one and 10.168.2.x for the other.

Then, just connect your 3g modem to the TP Link. Check to make sure you have an internet connection by connecting a computer to the DMZ port. Go to a web site that does a port scan and see if it can fine open ports (it should). This means your dmz is working correctly. You may have to configure the dmz in the tp link config first.

Next, plug the second router WAN port into the TP Link DMZ port. Now the second router will have an IP address in the TP Link LAN range. It will not be your external IP address. Connect a computer behind the second router and make sure it has Internet access. And you're done.

You should test this setup with anything that needs direct port access like ftp, bit torrents, skype, etc. If everything works okay, you're done.