Documentation/networking/bridge.rst

1 .. SPDX-License-Identifier: GPL-2.0
10 The IEEE 802.1Q-2022 (Bridges and Bridged Networks) standard defines the
23 .. kernel-doc:: net/bridge/br_private.h
33 -------------------------
35 .. kernel-doc:: include/uapi/linux/if_link.h
39 ------------------------------
41 .. kernel-doc:: include/uapi/linux/if_link.h
45 ------------
62 <https://lore.kernel.org/netdev/20220316150857.2442916-1-tobias@waldekranz.com/>`_.
64 The 802.1D-2004 removed the original Spanning Tree Protocol, instead
70 Bridge Ports and STP States
71 ---------------------------
73 In the context of STP, bridge ports can be in one of the following states:
74   * Blocking: The port is disabled for data traffic and only listens for
83   * Disabled: The port is administratively disabled and does not participate
84     in the STP process. The data frames forwarding are also disabled.
87 ---------------------------
91 for the spanning tree algorithm to create a loop-free topology.
113      shortest path to the root bridge and, in doing so, create a loop-free
115   6. Forwarding Ports: After the root bridge is selected and the spanning tree
116      topology is established, each bridge determines which of its ports should
118      the blocking state (used to prevent loops). The root bridge's ports are
119      all in the forwarding state. while other bridges have some ports in the
121   7. Root Ports: After the root bridge is selected and the spanning tree
122      topology is established, each non-root bridge processes incoming
123      BPDUs and determines which of its ports provides the shortest path to the
127   8. Designated ports: A designated port is the port through which the non-root
128      bridge will forward traffic towards the designated segment. Designated ports
129      are placed in the Forwarding state. All other ports on the non-root
142 ---------------------
144 The user space STP helper *bridge-stp* is a program to control whether to use
145 user mode spanning tree. The ``/sbin/bridge-stp <bridge> <start|stop>`` is
146 called by the kernel when STP is enabled/disabled on a bridge
157 area. LANs can be wired (using Ethernet cables) or wireless (using Wi-Fi).
168 called *VLAN-tagged frames*. IEEE 802.1ad, commonly known as QinQ or Double
172 <https://lore.kernel.org/netdev/1402401565-15423-1-git-send-email-makita.toshiaki@lab.ntt.co.jp/>`_
175 `VLAN filtering <https://lore.kernel.org/netdev/1360792820-14116-1-git-send-email-vyasevic@redhat.c…
176 on a bridge is disabled by default. After enabling VLAN filtering on a bridge,
189 ------------------
195 between multicast group addresses and the ports where hosts have joined these
199 broadcasting the multicast traffic to all ports, it sends the multicast
200 traffic based on the destination MAC address only to ports which have
208 ------------------------
212 <https://lore.kernel.org/netdev/20210120145203.1109140-1-razor@blackwall.org/>`_
228 ------------------------
230 The Linux bridge also supports `per-VLAN multicast snooping
231 <https://lore.kernel.org/netdev/20210719170637.435541-1-razor@blackwall.org/>`_,
232 which is disabled by default but can be enabled. And `Multicast Router Discovery
233 <https://lore.kernel.org/netdev/20190121062628.2710-1-linus.luessing@c0d3.blue/>`_,
261 The older ebtables tool is more feature-limited compared to nftables, but
282 netfilter hooks from the bridge so users had access to the more feature-rich
296 <https://lore.kernel.org/netdev/20200426132208.3232-1-horatiu.vultur@microchip.com/>`_,
298 <https://lore.kernel.org/r/20201124082525.273820-1-horatiu.vultur@microchip.com>`_,
300 <https://lore.kernel.org/netdev/20220218155148.2329797-1-schultz.hans+netdev@gmail.com/>`_,
302 <https://lore.kernel.org/netdev/20221101193922.2125323-2-idosch@nvidia.com/>`_.
308 ----------------------
315 ------------------------------
326 are discussed on the linux-netdev mailing list netdev@vger.kernel.org and
329 The list is open to anyone interested: http://vger.kernel.org/vger-lists.html#netdev