understanding gateway

[patrick sullivan]

My current setup works perfectly. I have a business charter (ISP) modem that has 3 Ethernet ports. I run all three to separate routers (details below as to why). But, I am wanting to loose the business modem and save some $$. The residential modem only has one Ethernet port. What can I do?

networks:

-Asus 68u with Merlin for VPN
-Linksys router for xbox live on 3 boxes throughout the house
-Sophos UTM for main home network.

I realize that I could condense to one router IF I knew what I was doing. But, my current setup works perfect. My VPN is fully configured. My xbox life network is very fast with zero lag, and my main network is heavily protected and I enjoy playing with the UTM.

suggestions??

 

[coxhaus]

Why can't you add a small switch between the residential modem and your other networks. This is assuming you are running double NAT.

Default gateway is a layer 2 forwarding process for switches.

Default route is a layer 3 forwarding for routers.

Default gateway and default route are not the same.

 

[patrick sullivan]

Remember coxhaus, I don't "know what I'm doing". My current setup is not double NAT. Each router comes off the modem.

I have a cheap, unmanaged switch....I doubt that would work though.....I was going to try that, but from what I have read, ISP's only allow one router to function behind a modem (even with a switch)

 

[coxhaus]

My answer was to use double NAT. You need a router at the modem or the modem in router mode to hand out IP addresses to your other 3 routers.

If you were using static IP addresses from a block of 5 then I doubt you can run all 3 routers at the same time without some changes.

PS
I don't like double NAT but people use it.

 

[patrick sullivan]

Well, to my surprise, this worked. I was able to connect my UTM behind the modem as before, which provides DHCP (192.168.1.1)to the network. That is connected to a managed switch, which I plugged my Asus 68-u into. It worked! I thought for sure there would have been some IP conflict having two "routers" connected. The Asus is set to DHCP as well, but on a different gateway (192.168.2.1). Not sure if that is why it worked? My Asus is still running the VPN successfully without changing any settings.

In contrast, the Linksys router (xbox live network) did NOT successfully connect after plugging it into the same switch. I can live with that- eliminate that setup all together. Interesting that the Asus had no problem though....