I will consider migrating port mirroring related configuration and code from `vyatta-cfg-qos` to the configuration template of all interfaces in `vyos-1x`, and support mirroring two-way traffic on the interface
https://github.com/vyos/vyatta-cfg-qos/blob/current/scripts/vyatta-qos.pl#L322-L346
https://github.com/vyos/vyatta-cfg-qos/blob/current/templates/interfaces/ethernet/node.tag/mirror/node.def
https://adamkuj.net/blog/2016/05/18/pro-tip-port-mirroring-in-linux/