Multiple Routers on smart switch

[Emanon12]

I have a TP-Link TL-SG108E smart switch with single NIC OpenWRT x86 router that is functionally normal.  I would like to be able to add a second router to the switch that so that the two routers/networks cannot see each other.  I have tried various configurations with the switch but cannot get a second router connected to Port 8 to connect to the internet.  I would really appreciate some help on accomplishing this.  I've set ports 1, 7, 8 back to default to start fresh.  My VLAN config and PVID settings are attached.  Thank you.

[deanwebb]

https://www.tp-link.com/us/support/faq/788/ looks like it has the answer, example 1. Looks like they need to be untagged ports and that VLAN 1 needs to include all the ports involved for Internet traffic to work with those VLANs.

[Emanon12]

My setup is a little different than Example 1 and to simplify troubleshooting I'm using 2 "regular" routers and not the x86 OpenWrt.  Configuring VLAN as the FAQ recommends, the two routers do not get a gateway address.  If I replace the cable modem with another router, Router0 and Router1 will get a gateway address. What do I need to do to get Router0 and Router1 to communicate with the cable modem?

[deanwebb]

Routers 0 and 1 would both need an IP on the same range as the Cable Modem OR the switch itself is set up with another VLAN that both routers can communicate with.

[Emanon12]

Routers 0 and 1 would both need an IP on the same range as the Cable Modem

How would I do that?  Isn't the cable modem getting the IP address dynamically from ISP that the routers pick up as the gateway?

[icecream-guy]

usually the cable _modem_ is a layer 1 device, a modem.

[Emanon12]

usually the cable _modem_ is a layer 1 device, a modem.

?

[icecream-guy]

usually the cable _modem_ is a layer 1 device, a modem.

?

modem, (from "modulator/demodulator"), any of a class of electronic devices that convert digital data signals into modulated analog signals suitable for transmission over analog telecommunications circuits. A modem also receives modulated signals and demodulates them, recovering the digital signal for use by the data equipment. Modems thus make it possible for established telecommunications media to support a wide variety of data communication, such as e-mail between personal computers, facsimile transmission between fax machines, or the downloading of audio-video files from a World Wide Web server to a home computer.

[Emanon12]

Sorry, I don't understand how that helps solve my connection issue through the switch.

[icecream-guy]

Sorry, I don't understand how that helps solve my connection issue through the switch.

cable modem, the layer 1 device, cannot route packets.
you cannot replace the cable modem with a router.
I digress.

[Emanon12]

I was just using the router as "fake internet" to see if the Vlans were set up somewhat correctly.  I'm not trying have the modem route, but I think I'm trying to split the WAN through the smart switch,  What I am trying to accomplish is having two networks that can't see each other on the switch so that I can have the home network on a temporary router while experiment on the OpenWRT router to get it set up without repeatedly affecting everything else in the home.  I want to have the temp router and OpenWRT both on 192.168.1.1 so I can move everything to the OpenWRT once it is completely set up and not have to change static IP's on servers...  Maybe this is not possible.

[Emanon12]

I did a lot of reading and it looks like I currently have Modem -> Layer 2 Switch -> Routers and I need Modem -> Layer 3 Switch -> Routers.  I have a Dell PowerConnect 28xx switch and will dive down that rabbit hole and see what kind of mess I can make.

[deanwebb]

Yes, that would be the right conclusion. It's layer 3 that allows for the interconnection of VLANs.

[config t]

I'm curious if he sorted it out. Bit of a science project there.

[Emanon12]

Unfortunately, it did not work with the PowerConnect 2808.  I think the problem now is that this switch does not have NAT.  One router would pick up IP address from modem and not the switch's DHCP server (I don't understand why that happens).  The other router would not get an IP address, subnet, gateway...