Skip to content

Juniper vMX#

Juniper vMX virtualized router is identified with juniper_vmx kind in the topology file. It is built using vrnetlab project and essentially is a Qemu VM packaged in a docker container format.

Juniper vMX nodes launched with containerlab come up pre-provisioned with SSH, SNMP, NETCONF and gNMI services enabled.

Managing Juniper vMX nodes#


Containers with vMX inside will take ~7min to fully boot.
You can monitor the progress with docker logs -f <container-name>.

Juniper vMX node launched with containerlab can be managed via the following interfaces:

to connect to a bash shell of a running Juniper vMX container:

docker exec -it <container-name/id> bash

to connect to the vMX CLI

ssh admin@<container-name/id>

NETCONF server is running over port 830

ssh admin@<container-name> -p 830 -s netconf

using the best in class gnmic gNMI client as an example:

gnmic -a <container-name/node-mgmt-address> --insecure \
-u admin -p admin@123 \


Default user credentials: admin:admin@123

Interfaces mapping#

Juniper vMX container can have up to 90 interfaces and uses the following mapping rules:

  • eth0 - management interface connected to the containerlab management network
  • eth1 - first data interface, mapped to a first data port of vMX line card
  • eth2+ - second and subsequent data interface

When containerlab launches Juniper vMX node, it will assign IPv4/6 address to the eth0 interface. These addresses can be used to reach the management plane of the router.

Data interfaces eth1+ need to be configured with IP addressing manually using CLI/management protocols.

Features and options#

Node configuration#

Juniper vMX nodes come up with a basic configuration where only the control plane and line cards are provisioned, as well as the admin users and management interfaces such as NETCONF, SNMP, gNMI.

Starting with hellt/vrnetlab v0.8.2 VMX will make use of the management VRF1.

Startup configuration#

It is possible to make vMX nodes boot up with a user-defined startup-config instead of a built-in one. With a startup-config property of the node/kind user sets the path to the config file that will be mounted to a container and used as a startup-config:

      kind: juniper_vmx
      startup-config: myconfig.txt

With this knob containerlab is instructed to take a file myconfig.txt from the directory that hosts the topology file, and copy it to the lab directory for that specific node under the /config/startup-config.cfg name. Then the directory that hosts the startup-config dir is mounted to the container. This will result in this config being applied at startup by the node.

Configuration is applied after the node is started, thus it can contain partial configuration snippets that you desire to add on top of the default config that a node boots up with.

Lab examples#

The following labs feature Juniper vMX node:

Known issues and limitations#

  • when listing docker containers, Juniper vMX containers will always report unhealthy status. Do not rely on this status.
  • vMX requires Linux kernel 4.17+
  • To check the boot log, use docker logs -f <node-name>.