VLAN tagged interface on the Raspberry

When you have only one cable available on your Raspberry Pi and you want to test something out with multiple networks this can be done with adding a tagged interface to your Raspberry on-board interface.

We can also call this a Raspberry on a stick configuration (this will only makes sense to people who knows what a router on a stick is)

My sources where this and this.

Lab Setup

Drawing

pub?w=976&h=585&.png

Switch config

!
vlan 4
 name RPI1-TAGGED
!
interface Vlan4
 ip address 10.10.10.1 255.255.255.0
 no shut
!
ip dhcp excluded-address 10.10.10.1 10.10.10.50
!
ip dhcp pool RPI1-TAGGED
 network 10.10.10.0 255.255.255.0
 default-router 10.10.10.1
!
vlan 20
 name RPI1-UNTAGGED
!
interface Vlan20
 ip address 20.20.20.1 255.255.255.0
 no shut
!
ip dhcp excluded-address 20.20.20.1 20.20.20.50
!
ip dhcp pool RPI1-UNTAGGED
 network 20.20.20.0 255.255.255.0
 default-router 20.20.20.1
!
interface GigabitEthernet0/1
 description CON-TO-RPI1-TAGGED
 switchport trunk encapsulation dot1q
 switchport mode trunk
 no shut
!
interface GigabitEthernet0/2
 description CON-TO-RPI1-UNTAGGED
 switchport access vlan 20
 switchport mode access
 no shut
!

RPi1–XX instructions

THIS EXAMPLE USES VLAN4, BUT WHEN TESTING IN THE NETWORK THE VLAN# NEEDS To BE CHANGED WITH THE ONE TRUNKED

Make sure you make ALL network interface related changes on the console

Unordered List Item
Turn on the RPi1-XX
Make sure there a TV / Monitor, the power, a keyboard and the network is connected to the RPi1-XX
verify the current network settings

[pidora@RPi1-XX ~]$ ip a
[pidora@RPi1-XX ~]$ more /etc/sysconfig/network-scripts/ifcfg-eth0

move the current network settings

[pidora@RPi1-XX ~]$ sudo mkdir /home/pidora/backup
[pidora@RPi1-XX ~]$ sudo mv /etc/sysconfig/network-scripts/ifcfg-eth0 /home/pidora/backup/

copy the current network settings to the VLAN tagged interface

[pidora@RPi1-XX ~]$ sudo cp /home/pidora/backup/ifcfg-eth0 /etc/sysconfig/network-scripts/ifcfg-eth0.4

make sure the content of the "ifcfg-eth0.4" file looks like this with vi:

[pidora@RPi1-XX ~]$ sudo vi /etc/sysconfig/network-scripts/ifcfg-eth0.4

DEVICE=eth0.4
BOOTPROTO=dhcp
ONBOOT=yes
VLAN=yes
NM_CONTROLLED=no

make sure the 8021q module is loaded

[pidora@RPi1-XX ~]$ sudo lsmod | grep 8021q

if its not loaded then load it

[pidora@RPi1-XX ~]$ sudo modprobe 8021q

when the RPI1-XX is rebooted the module is not loaded automatically.
to make this happen we need to do the following

[pidora@RPi1-XX ~]$ sudo  sh -c 'grep -q 8021q /etc/modules || echo 8021q >> /etc/modules'

restart the network settings

[pidora@RPi1-XX ~]$ sudo systemctl restart network.service

verify if an IP address in the correct range is given

[pidora@RPi1-XX ~]$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default 
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
    link/ether b8:27:eb:fc:7a:fa brd ff:ff:ff:ff:ff:ff
    inet6 fe80::ba27:ebff:fefc:7afa/64 scope link 
       valid_lft forever preferred_lft forever
3: eth0.4@eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default 
    link/ether b8:27:eb:fc:7a:fa brd ff:ff:ff:ff:ff:ff
    inet 10.10.10.51/24 brd 10.10.10.255 scope global dynamic eth0.10
       valid_lft 85236sec preferred_lft 85236sec
    inet6 fe80::ba27:ebff:fefc:7afa/64 scope link 
       valid_lft forever preferred_lft forever