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I want to setup a wired network where I have the modem plugged into a switch. Is it required that the router be the first connection to the Modem as long as all the network traffic is routed through the router? Would something like this work?

Modem -> Switch <- Network Printer, PC & Router connected to the switch Router set as default gateway on all PC's

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Do you have a specific reason to do this? I think it might actually work, but I am not sure. However, it does not seem to make sense. – Jan Schejbal Feb 6 '13 at 2:17
I want the router to be accessible. The switch would allow me to save a significant amount of trouble in my cable run by allowing to drop the wall jacks without having to wire to the router and then waste wire and having to retrace my cable run. – Usta Feb 6 '13 at 2:25
Normally the modem sits between the router and the internet, whereas the switch would be your internal network. Can you provide models numbers to understand the layout better? – Paul Feb 6 '13 at 2:29
up vote 0 down vote accepted

Assuming the modem is a PPPoE device, it would probably actually work. The switch switches around Ethernet (Layer 2) frames, and the router uses PPPoE to communicate with the modem. PPPoE works via Ethernet (as the name suggests), and seems to use its own discovery protocol to find the MAC address of the modem. It should be able to coexist with IP in one network. So, in theory, if you connected the router's "modem" ethernet port to the switch, and connected the router's "network" ethernet port to the switch using a second cable, it should work. Note that you will have to connect both the "network" ethernet port and the "modem" ethernet port to the switch. Test before installing, obviously. Note that you may have to fiddle around with crossover/non-crossover cables.

It doesn't make much sense, however, and can lead to various problems and security issues (do you want any PC in the network to be able to establish PPPoE sessions?). Instead of running the "modem" cable from the router to the switch and from the switch to the modem, just run it directly from the router to the modem. If you are working with wall jacks, you can connect two of them directly with a cable instead of using one cable to connect jack A to a switch and a second one connect the switch to jack B.

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Thanks! I eventually decided on an alternative wiring plan, but I think this looks like it would also have worked. – Usta Feb 13 '13 at 2:11

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