Nicholas Morrison - Networking Specialist

flokinet-004 - VLANs

Connecting to the lab server

  • Open your favourite Terminal Emulator
  • SSH to the netlab server:
  • $ ssh-keygen -R   <- delete the cached fingerprint
                                            (lab server rebuilt frequently)
    $ ssh
    Password: (generated fresh each week)
  • List the running containerlab devices:
  • $ sudo containerlab inspect --all
  • Connect to an Arista device:
  • $ sudo docker exec -it clab-device–name Cli
  • .. or connect to a Linux device:
  • $ sudo docker exec -it clab-pcXX-name bash


Topology 02


  • all devices in the same VLANs can ping each other.

What you are responsible for configuring

  • the two PCs connected to your switch
  • your switch (switch-XX)
  • your uplink port on core-01

Creating VLANs

vlan 10
   name web
vlan 20
   name mail
! etc etc

Configuring access (untagged) ports

interface ethernet 2
   description -- link to web-b --
   switchport mode access
   switchport access vlan 10

Configuring trunk (tagged) ports

interface ethernet 1
   description -- link to switch-01 --
   switchport mode trunk
   switchport trunk allowed vlan 10,20

Looking at the dot1q tags

Look at packets without VLAN tags:

bash# tcpdump -i eth2 icmp

web-a# ping

Look at packets with VLAN tags:

bash# tcpdump -i eth1 icmp
web-a# ping

Inspecting the core switch

show mac address-table
show ip arp
show ip route
ping 192.168.x.x


  • Can the switch ping the PCs?
  • Can the PCs ping the switch?
  • Is “core-01” routing packets?