[RFC PATCHv3 net-next 06/10] docs: bridge: add VLAN doc

[Hangbin Liu <liuhangbin@gmail.com>]

Add VLAN part for bridge document.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 Documentation/networking/bridge.rst | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/Documentation/networking/bridge.rst b/Documentation/networking/bridge.rst
index e168f86ddd82..88dfc6eb0919 100644
--- a/Documentation/networking/bridge.rst
+++ b/Documentation/networking/bridge.rst
@@ -135,6 +135,35 @@ Proper configuration of STP parameters, such as the bridge priority, can
 influence which bridge becomes the Root Bridge. Careful configuration can
 optimize network performance and path selection.
 
+VLAN
+====
+
+A LAN (Local Area Network) is a network that covers a small geographic area,
+typically within a single building or a campus. LANs are used to connect
+computers, servers, printers, and other networked devices within a localized
+area. LANs can be wired (using Ethernet cables) or wireless (using Wi-Fi).
+
+A VLAN (Virtual Local Area Network) is a logical segmentation of a physical
+network into multiple isolated broadcast domains. VLANs are used to divide
+a single physical LAN into multiple virtual LANs, allowing different groups of
+devices to communicate as if they were on separate physical networks.
+
+Typically there are two VLAN implementations, IEEE 802.1Q and IEEE 802.1ad
+(also known as QinQ). IEEE 802.1Q is a standard for VLAN tagging in Ethernet
+networks. It allows network administrators to create logical VLANs on a
+physical network and tag Ethernet frames with VLAN information, which is
+called *VLAN-tagged frames*. IEEE 802.1ad, commonly known as QinQ or Double
+VLAN, is an extension of the IEEE 802.1Q standard. QinQ allows for the
+stacking of multiple VLAN tags within a single Ethernet frame. The Linux
+bridge supports both the IEEE 802.1Q and `802.1AD
+<https://lore.kernel.org/netdev/1402401565-15423-1-git-send-email-makita.toshiaki@lab.ntt.co.jp/>`_
+protocol for VLAN tagging.
+
+The `VLAN filtering <https://lore.kernel.org/netdev/1360792820-14116-1-git-send-email-vyasevic@redhat.com/>`_
+on bridge is disabled by default. After enabling VLAN
+filter on bridge, the bridge can handle VLAN-tagged frames and forward them
+to the appropriate destinations.
+
 FAQ
 ===
 
-- 
2.41.0