Simple question on CM1200

[donawalt]

This is a simple question for many I am sure, but I could not find the answer in the CM1200 modem...

That modem has 4 RJ45 ports on it - #1 goes to my router; #2 is preferred for link aggregation. I could not find any documentation how to use #3 and #4. What I tried was this --

I currently have my system set up with the CM1200 connected to my WiFi router through port #1, and from my router there is an RJ45 cable to my Ethernet switch - which goes to three places.

What I thought might be more efficient was to have RJ45 cables go direct to the router (through port #1) and the switch (through port #3), but I could not get that to work. I tried restarting the modem, the switch, but no internet access was available to the ports connected through the switch.

What am I doing wrong, or is this not how ports #3 and #4 on the CM1200 are to be used? Thanks!

[plemans · Accepted solution]

Who's your ISP? 

The majority of the big ISP's only support 1 device connected to a modem. 

this happens because they only assign 1 public IP address to each modem. Not multiple public IP addresses. 

So for most users, the extra ports on the CM1200 are useless. 

Sadly Netgear and ISP's do a poor job of explaining modems with mutiple ports. 

there are a few ISP's the support multiple public IP address but they're rare and tend to be smaller ISP's. 

The larger ISP's will support the ports if you pay for a business class line that supports the extra IP addresses but it costs more and isn't worth it. Reason why is you can just a switch to the router if you're needing more ports. The cost isn't worth it for consumers versus business want it for data seperation. 

[plemans · Accepted solution]

Who's your ISP? 

The majority of the big ISP's only support 1 device connected to a modem. 

this happens because they only assign 1 public IP address to each modem. Not multiple public IP addresses. 

So for most users, the extra ports on the CM1200 are useless. 

Sadly Netgear and ISP's do a poor job of explaining modems with mutiple ports. 

there are a few ISP's the support multiple public IP address but they're rare and tend to be smaller ISP's. 

The larger ISP's will support the ports if you pay for a business class line that supports the extra IP addresses but it costs more and isn't worth it. Reason why is you can just a switch to the router if you're needing more ports. The cost isn't worth it for consumers versus business want it for data seperation. 

[donawalt]

Thank you for your reply, that makes total sense! Everything works fine with the switch going thru the router, I just wondered why those ports were there. BTW my ISP is Comcast.

[plemans]

yeah, comcast doesn't support the mutliple public IP's unless you pay for them. I have comcast and they'll do whatever they can for extra $.