SPAN port mirroring can copy the inbound/outbound traffic of the interface to the 
specified interface, usually the interface can be connected to some special equipment,
such as behavior control system, intrusion detection system and traffic collector, 
and can copy all related traffic from this port

VyOS uses the `mirror` option to configure port mirroring. The configuration is divided
into 2 different directions. Destination ports should be configured for different traffic directions.

.. cfgcmd:: set interfaces {{ var0 }} <interface> mirror ingress <monitor-interface>

   Configure port mirroring for `interface` inbound traffic and copy the traffic to `monitor-interface`

.. cfgcmd:: set interfaces {{ var0 }} <interface> mirror egress <monitor-interface>

   Configure port mirroring for `interface` outbound traffic and copy the traffic to `monitor-interface`