Connecting 2 Routers with a Switch?

[Geekasaurus2]

Hello,
I just got a Xfinity Home Security system. I did not know beforehand that the setup entailed installing a wireless router that is separate from my regular router. It is set up to run BEFORE my regular router. In other words, it goes modem - Xfinity router - my router. The problem is that the cheapo Netgear router they use does not have gigabit ports on it. My modem now indicates it is not gigabit either. I paid a fair amount of money upgrading so I have a gigabit modem/router and network port on my computer.
I called Comcast and they told me to use a switch to separate them. My question is does this mean I hook up the switch right after the modem, and then plug the two routers into the switch, one into a separate port?
From what I am trying to learn about switches, you can't plug them in directly to the modem and then routers, it has to be a router and then a switch..Basically I am confused! I am just having a hard time figuring it out and not happy that there has to be more equipment under my desk. I know there are wireless gateways, but I am quite happy with the router and modem I currently have.

 

[bill001g]

So does comcast let you 2 IP addresses behind the modem. If yes then just put a switch after the modem and let each router talk directly. The answer used to always be no but some ISP actually allow this.

If not then the next question would be does it really matter. As long a the Xfininity router can go faster than your ISP it is good enough. A GIG port will not make it run any faster. The only place it matters is if you were to stream data INSIDE your house which can go faster than 100m. As long as you make sure it is connected to your gig router the xfinity router will only be used for internet.

The larger concern would be have 2 router in general. The dual NAT and port mapping issues could cause you a problem for certain application (ie games).

Don't know a lot about the xfinity device but I bet if you worked at it you could place it behind YOUR router rather than in front.