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Setup:

ISP
 +
 +  ---------------------    -----------------------------------------
 +  | Internet Modem    |    | Router 1                              |
 +  |                   |    |                                       |
 +  | CABLE     ETHERNET|    |  WAN    LAN1    LAN2     LAN3    LAN4 |
 +  |-- + -------- + ---|    |-- + ------------------------------ + --
 ++++++++          +++++++++++++++                                +
                                                                  +
                                 ++++++++++++++++++++++++++++++++++
                                 +                                
                             |-- + -----------------------------------
                             |  WAN    LAN1    LAN2     LAN3    LAN4 |
                             |                                       |
                             |                                       |
                             | Router 2                              |
                             -----------------------------------------
Router 1 = LinksysEA2700
Router 2 = unknown for now (don't have access to it yet)

Router 1 IP = 192.168.1.1 DHCP enabled
Router 2 IP = 192.168.2.1 DHCP enabled

I have a few questions:

  1. Will clients connected to network Router 1 and Router 2 have access to Internet? (there won't be any firewall or other restrictions)
  2. Will clients connected to Router 1 be able to see data from clients on Router 2?
  3. Will clients connected to Router 2 be able to see data from clients on Router 1?

Basicly what I need is 2 separate (isolated) networks.

Thank you!

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migrated from serverfault.com Mar 14 '13 at 3:13

This question came from our site for professional system and network administrators.

    
You mean Linksys EA2700? –  devicenull Mar 14 '13 at 2:52
    
@devicenull: you're right it's Linksys. –  Simon Arsenault Mar 14 '13 at 2:56
    
Are we trying to avoid double NAT? –  Matthew Mar 15 '13 at 16:05

4 Answers 4

I'm assuming your using basic SOHO or home equipment here. Based on what you've provided, clients behind both routers will have Internet access. Clients attached to RT1 will only be able to talk to the Internet and their connected peers, and clients attached to RT2 will be able to talk to everything.

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Yes, I'll be using home equipment. I'd like to prevent clients on Router 2 to talk to clients on Router 1 and vice-versa. –  Simon Arsenault Mar 14 '13 at 3:02
    
@SpacemanSpiff it seems that would be the easiest, but i guess the QA wants 2 subnets which are isolated from one another. your point would be rather easy, making a subnet on router 2 having router 1 only as wan would solve things your way, as long as there were no port forwards. –  Lorenzo Von Matterhorn Mar 14 '13 at 3:21
    
I don't need port forwarding on Router 2. Not sure about Router 1. –  Simon Arsenault Mar 14 '13 at 3:34
    
you only need port forwarding if there is a specific need for it by any application. –  Lorenzo Von Matterhorn Mar 14 '13 at 3:36
    
you could easily accomplish this with THREE SOHO routers... –  SpacemanSpiff Mar 14 '13 at 4:44

All 3 questions depend on how the routers are configured. But assuming they are not doing any filtering then I would assume the following is likely

  1. Yes
  2. No NAT (with routes configured) - Yes.
    NAT - No.
  3. Yes

If the cable modem has more than one ethernet port then connect Router2 WAN to the other ethernet port on the internet modem. If it doesn't you could connect it to a 5 port switch and then connect each router to that switch. Then turn on NAT for both router 1 & 2 and you'll have two independent LAN's that can't talk to each other.

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The easiest and cost-effective way would be as follows enter image description here

cable modem connected to Router 1 wan; Router 1 connected to Router 2 using Lan port -> Wan port;

Answering your specific 3 questions: Creating a subnet on Router2 having router 1 as Wan - Router 1 has access to Router 2, the opposite is not done.

EDIT

If the cable modem has more than 1 port, connect both routers there and turn on NAT for both. Future connections across routers would not be possible.

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What I would do is get a simple 5-port switch, and run that off of the modem directly. Then off the switch, add the two routers, each plugged into the WAN port. This will make them completely independent of each other, and both access the Internet. The two routers will only let computers attached to each one connect to each other, but not through the other router.

When doing it this way, you need to make sure your ISP will give you 2 IP addresses. In Canada, I know that Telus and Shaw give two IP addresses for their accounts, even to home users

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Why do I need 2 IPs? –  Simon Arsenault Mar 15 '13 at 22:24
    
Because the switch doesn't get an IP address; each router thinks it's hooked directly to the modem, so each of them needs an IP address for the Internet –  Canadian Luke Mar 15 '13 at 22:27
1  
If the OP is going to purchase hardware, I would purchase an inexpensive wired router. You will only need one IP from the ISP and the other two routers will get an IP address from the third router making them completely independent networks. –  wbeard52 Feb 17 at 16:58

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