Sending Untagged Traffic Without VLAN ID to Remote End
Send traffic without the native VLAN ID (native-vlan-id) to the remote end of the network if untagged traffic is received.
This feature works only on MX series routers with MPCs/MICs. Configuring this option with DPC results in no behavior change. But, if this option is configured with Aggregated Ethernet (AE) in which the sub interfaces reside across MPCs/MICs and DPC, MPCs/MICs and DPC will show a different behavior.
In the egress direction, this feature is disrupted by VLAN normalization. Because of normalization, the egress interface cannot distinguish between untagged traffic and tagged traffic. And untagged traffic is sent out with native-vlan-id. Consider this while configuring both VLAN normalization and new native-vlan-id option.
There will be a problem with ingress firewall filter if filter term includes native-vlan-id. With no-native-vlan-insert option configured, native-vlan-id will not be inserted to untagged traffic. So, firewall filter term will not match with untagged traffic. But if incoming traffic have VLAN ID which is equal to native-vlan-id, then firewall filter term will match and firewall will work.
When this feature is used with AE, all sub-interfaces of AE should be in same type of FPC.