Running netlab on a Linux Server

This page describes generic installation steps you have to follow to create a virtual lab environment on any Linux server. If you plan to run your labs on a Ubuntu server, follow these instructions.

Prerequisite Software Installation

netlab is a Python package that uses KVM to run virtual machines and Docker to run containers. Virtual machines in KVM environment and the associated Linux bridges are created with Vagrant using libvirt API. Ansible is used to configure the network devices.

netlab on Linux

To build a Linux environment needed to run network devices as virtual machines or containers:

  • Install Python 3.7 or later

  • Install KVM and libvirt

  • Install Vagrant 2.2.14 or later

  • Install vagrant-libvirt plugin with vagrant plugin install libvirt --plugin-version=0.4.1

  • Install Ansible 2.9.1 or later and any Ansible networking dependencies (example: paramiko)

  • Optional: install Docker and containerlab

netlab Installation

Install Python package with sudo python3 -m pip install networklab or your preferred Python package installation procedure.

Create vagrant-libvirt Virtual Network

Vagrant libvirt provider connects management interfaces of managed VMs to vagrant-libvirt virtual network. Vagrant can figure out the device IP address based on dynamic DHCP mappings; netlab can’t. To make the Ansible inventory created by netlab create tool work, your virtual network MUST include static DHCP bindings that map management MAC addresses defined in netlab data model into expected IP addresses.

The static DHCP bindings must map MAC addresses 08:4F:A9:00:00:xx into IP addresses 192.168.121.1xx. The easiest way to create the virtual network and static DHCP mappings is to use the netsim/templates/provider/libvirt/vagrant-libvirt.xml file supplied with netlab:

  • If needed, delete the existing vagrant-libvirt network with virsh net-destroy vagrant-libvirt and virsh net-undefine vagrant-libvirt

  • Create the management network with virsh net-create _path_/vagrant-libvirt.xml. The management network is also created (if needed) every time you execute netlab up.

You could also use virsh net-edit vagrant-libvirt to edit the XML definition of your existing vagrant-libvirt network – replace the exiting ip element with this XML snippet:

<ip address='192.168.121.1' netmask='255.255.255.0'>
  <dhcp>
      <range start='192.168.121.2' end='192.168.121.99'/>
      <host mac='08:4F:A9:00:00:01' ip='192.168.121.101'/>
      <host mac='08:4F:A9:00:00:02' ip='192.168.121.102'/>
      <host mac='08:4F:A9:00:00:03' ip='192.168.121.103'/>
      <host mac='08:4F:A9:00:00:04' ip='192.168.121.104'/>
      <host mac='08:4F:A9:00:00:05' ip='192.168.121.105'/>
      <host mac='08:4F:A9:00:00:06' ip='192.168.121.106'/>
      <host mac='08:4F:A9:00:00:07' ip='192.168.121.107'/>
      <host mac='08:4F:A9:00:00:08' ip='192.168.121.108'/>
      <host mac='08:4F:A9:00:00:09' ip='192.168.121.109'/>
      <host mac='08:4F:A9:00:00:0A' ip='192.168.121.110'/>
      <host mac='08:4F:A9:00:00:0B' ip='192.168.121.111'/>
      <host mac='08:4F:A9:00:00:0C' ip='192.168.121.112'/>
      <host mac='08:4F:A9:00:00:0D' ip='192.168.121.113'/>
      <host mac='08:4F:A9:00:00:0E' ip='192.168.121.114'/>
      <host mac='08:4F:A9:00:00:0F' ip='192.168.121.115'/>
      <host mac='08:4F:A9:00:00:10' ip='192.168.121.116'/>
      <host mac='08:4F:A9:00:00:11' ip='192.168.121.117'/>
      <host mac='08:4F:A9:00:00:12' ip='192.168.121.118'/>
      <host mac='08:4F:A9:00:00:13' ip='192.168.121.119'/>
      <host mac='08:4F:A9:00:00:14' ip='192.168.121.120'/>
      <host mac='08:4F:A9:00:00:15' ip='192.168.121.121'/>
      <host mac='08:4F:A9:00:00:16' ip='192.168.121.122'/>
      <host mac='08:4F:A9:00:00:17' ip='192.168.121.123'/>
      <host mac='08:4F:A9:00:00:18' ip='192.168.121.124'/>
      <host mac='08:4F:A9:00:00:01' ip='192.168.121.101'/>
	</dhcp>
</ip>

For more details, see Using Libvirt Provider with Vagrant by Brad Searle.

Testing the Installation

The easiest way to test your installation is to use netlab test command. If you prefer to do step-by-step tests, you might find this recipe useful:

  • Create an empty directory and topology.yml file with the following contents within that directory:

---
defaults:
  device: cumulus

nodes: [ s1, s2, s3 ]
links: [ s1-s2, s2-s3, s1-s2-s3 ]

  • Create Vagrantfile with netlab create command

  • Execute vagrant up to spin up three Cumulus VX virtual machines

  • Connect to the Cumulus VX devices with vagrant ssh

  • Destroy the lab with vagrant destroy -f

Next Steps