docs/Networking/Docker/Creating a MACVLAN Sub-Interface.md

Purpose: You may find that you only have one network adapter on a server / VM and need to have multiple virtual networks associated with it. For example, Home Assistant exists on the 192.168.3.0/24 network but it needs to also access devices on the 192.168.4.0/24 surveillance network. To facilitate this, we will make a MACVLAN Sub-Interface. This will make a virtual interface that is parented to the actual physical interface.

!!! info "Assumptions" It is assumed that you are running Rocky Linux (or CentOS / RedHat).

Create the Temporary Interface

You will begin with making a new interface, it will have the name macvlan0.

ip link add macvlan0 link eno1 type macvlan mode bridge
ip addr add 192.168.4.100/24 dev macvlan0
ip link set macvlan0 up

Bind a Docker Network to the Sub-Interface

Now you need to run the following command to allow docker to use this interface for the surveillance_network

docker network create -d macvlan --subnet=192.168.4.0/24 --gateway=192.168.4.1 -o parent=macvlan0 surveillance_network

!!! warning "Not Reboot-Persistent Yet" Unfortunately due to a lack of documentation yet, I do not have a permanent configuration change to make this persistent, as such, you will need to re-run the commands above (at least the "Temporary Interface" section) in order to get it operational again after a system reboot.