Raspberry Pi 3 as Router with VLAN?


#1

Hi community,

I recently switched to wifi access poins that can broadcast multiple ssids and now I want to have multiple VLANs in my home network. Since my current router (FritzBox 7590) cannot handle VLANs I want to use a raspberry pi 3 with OpenWrt to route all my different VLANs and provide DHCP. My current router will be used as modem and DECT base.
heimetz-hardware

Is this possible what I'm thinking of?
And if so, how do I configure it?

Thanks in advance!
Manu


#2

Conceptually, yes. Practically, there are some significant challenges with the Raspberry Pi hardware, in specific.

Raspberry Pi, by their choice of architecture, can't handle more than a few hundred mbps over Ethernet, as it is limited by USB 2.0 connectivity to the SoC.

The Raspberry Pi wireless chips are generally Broadcom, which have very poor support with open-source drivers. (I believe that you license the proprietary Broadcom drivers when you install an "official" Raspberry Pi distro.)

Configuration is straightforward; create the VLANs on the Pi's single Ethernet interface, assign (static) IP addresses to each pseudo-interface, set up any static routes needed, set up your firewall as you see fit, and enable DHCP on each of the subnets.


#3

A ~30 USD Xiaomi mir3g would do a much better job at routing than any RPi to date, if you have the budget, a decent ipq40xx device for roughly twice that money would be an even better choice.


#4

Thank you! Since I'm new to OpenWrt, VLANs and so on, I decided to give it a try with a PineA64+ I had laying around.
I know it's not ideal, but I want to get to know everything first and figure out my needs before buying something in the €60 range.

Now my question is regarding the setup in OpenWrt.
My setup looks like the following;
network-current
But all the devices that are connected trough VLAN10 don't have internet access. DHCP works fine, but I cannot get the traffic to go like this:
Device → OpenWrt → Modem → www
218.201.10.100 → 218.201.10.1 → 192.168.1.1 → ISP

Ethernet-Port on the Pine is tagged (trunked)

Can you point me to the right direction?

Thanks in advance!


#5

In the OpenWrt firewall, do you have forwarding from the VLAN10 network to LAN? Also the LAN zone must be set for masq / mtu_fix.


#6

I have set up OpenWrt to act as DHCP for VLAN10 (218.201.10.0/24) and set the IPv4 Gateway to my modem (192.168.1.1).
When I connect a device to VLAN1o I get assigned an IP and I can ping both VLAN10 devices and also also my modem. But my devices still cannot connect to the internet.

I checked masquerading, but I couln't find anything regarding mtu-fix.

This is my firewall setup.
Bildschirmfoto%20vom%202018-12-06%2022-12-58

Any ideas?


#7

I have a setup similar to what you are trying to achieve. I'd recommend you start over with your Pi and switch and even your modem.

A quick side note: Why are you using 218.201.10.0/24 -- this is not an RFC1918 range. While possible to use, it may cause headaches in the future. Stick with RFC1918 address ranges (192.168.xxx.xxx, 10.xxx.xxx.xxx, 172.16.xxx.xxx)

First thing: can you modem be set to a true bridge mode such that a device connected to it gets a public IP (instead of being behind the router functions that will make the connection NAT'd and firewalled? If this is an option, you'll want to use it. If not, you'll be double-NAT'd, which is not usually a big deal, but can be less than ideal and can sometimes cause issues.

Next, define your VLANs. For the moment, I'm going to use LAN = 10, Guest = 20, and WAN = 100. And define your physical switchports for the connections (I'll assume Fritzbox = port 1, Pi = port 2)

On the managed switch, set the physical switchport (1) for the Fritzbox to have a PVID (default untagged) VLAN ID = 100. Similarly on the switchport that will connect to your Pi's ethernet port (2), set that to be a member of VLAN 100 (preference will dictate if this is tagged or untagged). Make sure that VLAN 100 is not assigned to any other switchports.

Also on the managed switch, set port 2 (pi) to use VLAN 10 and VLAN 20 (you've now got VLAN 10, 20, and 100 on that physical port -- at least 2 of those must be tagged, you can select which, if any, is untagged on that port.

Set all other ports on your switch to use VLAN10 and/or VLAN20 (often it is easiest to simply make them untagged on those ports, unless you are using a trunk port or will be connecting VLAN aware devices to those ports).

Now, on the Pi, set the VLANs on your ethernet port to be the same as those on the switch port 2. For example, if you tagged all 3 networks, then eth0.100 is your WAN interface (and should be associated with the WAN firewall zone) most likely with DHCP or PPPoE as the protocol. Your LAN will be eth0.10 (lan firewall zone), and eth0.20 is your guest (guest firewall zone -- you will still need to setup that zone). If you have chosen to have one of those networks untagged on port 2 of your switch, then it would be associated with eth0 directly (notice not eth0.xxx).

At this point, the switch will simply pass through the WAN/internet connection from port 1 to port 2 (and to no other ports participate on this), and then the other ports will get their LAN and/or Guest networks from the OpenWRT pi.

EDIT: don't forget that all networks need to exist on separate subnets as well as different VLAN IDs. So if your WAN comes through as a public IP, awesome. If not, make sure your LAN and Guest networks are not the same subnet as the fritzbox. Your fritzbox seems to be 192.168.1.1 and controlling a network 192.168.1.0/24. So you might want your LAN to be 10.0.10.0/24 and your Guest to be 10.0.20.0/24. Or really anything you want other than 192.168.1.0/24.

The port numbers, VLAN IDs, and IP subnets are just examples -- feel free to modify, but pay attention to the details around different subnets and the use of the VLANs and such.