VLAN 802.1q support

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.. _vlan_802.1q:

VLAN 802.1q support

Cilium enables firewalling on native devices in use and will filter all unknown traffic. VLAN 802.1q packets will always be passed through their main device with associated tag (e.g. VLAN device is eth0.4000 and its main interface is eth0). By default, Cilium will allow all tags from the native devices (i.e. if eth0.4000 is controlled by Cilium and has an eBPF program attached, then VLAN tag 4000 will be allowed on device eth0). Additional VLAN tags may be allowed with the cilium-agent flag --vlan-bpf-bypass=4001,4002 (or Helm variable --set bpf.vlanBypass="[4001,4002]").

The list of allowed VLAN tags cannot be too big in order to keep eBPF program of predictable size. Currently this list should contain no more than 5 entries. If you need more, then there is only one way for now: you need to allow all tags with cilium-agent flag --vlan-bpf-bypass=0.

.. note::

Currently, the cilium-agent will scan for available VLAN devices and tags only on startup.