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I just bought a 16 port switch for home networking. Should the flow go:
Modem > switch > wireless router and other devices?
Or should it go:
Modem > wireless router > switch > other devices?
The switch is a NETGEAR ProSAFE GS116NA 16-Port Gigabit Ethernet Switch (GS116NA) and will be used in the attic in an attempt to run Ethernet ports throughout the house.

  • I'm going to guess that your wireless router would be the biggest bottleneck in your setup so isolating it might be the best solution. This does require however that the modem is able to hand out IP addresses/DHCP. – GiantTree May 3 '17 at 16:01
  • What kind of router (SOHO or a real router)? This is important because any given SOHO router isn't capable of handling multiple IPs with the default software. Is the modem routed or bridged? This is important because it tells you where your demarcation point is for the IP layer and will better tell you where you want your switch. Are you getting a routed block? or just a few IPs? – MaQleod May 3 '17 at 16:51
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Based on everything you have provided, I strongly recommend Modem -> Router -> Switch

You cable Modem (if Modem it be; not one of the new modem/routers some ISPs use), then you only firewall is the Wifi Router, so you want your hosts to be behind it. Otherwise they are directly accessible from the ISP network (and likely the world at large).

Additionally, your ISP may not permit you to put the switch in line first, as hosts on the switch would pull their IP address from the ISP, not from your router, so your plan would need to allow sufficient ISP IPs for your hosts. Most ISPs grant only one of their IPs to a customer.

Finally, if you put the switch first, and attached hosts to it, they would be isolated from the hosts on Wifi or connected to the routers LAN switch, and the two realms would not be able to communicate without firewall modifications which may be difficult or impossible to restrict to only your hosts. Note that ISP IPs can change abruptly, without your knowledge or consent.

  • Ok, all that made sense. So the modem doesn't have a firewall thus putting all the devices on the switch behind the router's firewall is recommended. Then, switch first tries to pull multiple IP's from my ISP whereas if the router took the single ISP IP it would then make a subnetwork of IP's for the switch/devices correct? And lastly, I believe I ran into the exact scenario of point 3 awhile back. But it may have been devices connected to the router (it has 4 ports) couldn't talk to a hub that was connected to one of the ports. – toadfromgrove May 3 '17 at 16:31
  • One final followup question is: isn't the selling point of the switch that it's smart enough to route properly. So for a case in point #3, shouldn't traffic come to the modem, where it passes the traffic to the switch and the switch says is this a directly connected device of mine? no? then I need to push this to this IP that has the same IP up to this subnet number and let that device find where that IP is – toadfromgrove May 3 '17 at 16:34
  • No, switches are not routers, though there are enterprise devices called "Layer 3 switches" or "Brouters" that encompass the basic functionality of both a router and a switch or bridge. Unless you are using high end equipment, Switches cannot route. For point #3, I was more pointing out that devices connected to the switch are outside the routers LAN, so you cannot connect from a device on the switch to a device on the router, unless you open up the firewall for that traffic, and you are likely opening it for more than just your hosts. – Frank Thomas May 3 '17 at 16:59
  • The point of a switch, is that it is layer2 aware, so unlike a hub, it will only send traffic out the port that is connected to the system that is indicated as the recipient of the frame. A hub broadcasts every packet it receives on any port out all ports, so its a dumb megaphone. A switch however is smart and only sends traffic where needed. Additionally for a hub, the total speed for the hub is shared across all ports, whereas a switch has dedicated bandwidth per port. – Frank Thomas May 3 '17 at 17:02
  • That cleared the 'smart' aspect of a switch that I was wondering about. Thank you Frank! – toadfromgrove May 4 '17 at 15:58

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