Because LLC wasn't complicated/annoying enough, there's 2 more
"ethertypes" being used for it:

- 0x8870 is pretty "normal", it got standardized in
  802.1AC-2016/Cor1-2018 for transporting LLC frames > 1500 bytes.
  It simply replaces the length value (which is no longer encoded, and
  must now be derived from the packet.)  The actual value dates back to
  2001; https://datatracker.ietf.org/doc/html/draft-ietf-isis-ext-eth-01
  (it was used without "proper" standardization for a long time)

- 0x00fe is a doozy - actually "invalid" depending on how you look at
  it; it's used in GRE (and possibly GENEVE) tunnels to transport the
  IS-IS routing protocol.  https://seclists.org/tcpdump/2002/q4/61 is
  the best/oldest source I could find.  It's inspired by the 0xfe SAP
  value, a GRE packet with protocol 0x00fe is followed by a payload "as
  if" it was Ethernet with "<length> 0xfe 0xfe 0x03".  (Again the length
  isn't encoded explicitly anymore.)

The 0x00fe value is quite close to other values the kernel is using
internally for various things (after all they "won't clash for 1500
types").  Except this one does clash, and if someone unknowingly starts
using it for something internal... we end up in a world of pain in
getting IS-IS running on GRE tunnels.  Hence the "WARNING".

Signed-off-by: David 'equinox' Lamparter <equinox@diac24.net>
Cc: Andrew Lunn <andrew+netdev@lunn.ch>
Link: https://patch.msgid.link/20260605164144.81184-1-equinox@diac24.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The NXP NETC switch tag is a proprietary header added to frames after the
source MAC address. The switch tag has 3 types, and each type has 1 ~ 4
subtypes, the details are as follows.

Forward NXP switch tag (Type=0): Represents forwarded frames.
  - SubType = 0 - Normal frame processing.

To_Port NXP switch tag (Type=1): Represents frames that are to be sent
to a specific switch port.
  - SubType = 0. No request to perform timestamping.
  - SubType = 1. Request to perform one-step timestamping.
  - SubType = 2. Request to perform two-step timestamping.
  - SubType = 3. Request to perform both one-step timestamping and
    two-step timestamping.

To_Host NXP switch tag (Type=2): Represents frames redirected or copied
to the switch management port.
  - SubType = 0. Received frames redirected or copied to the switch
    management port.
  - SubType = 1. Received frames redirected or copied to the switch
    management port with captured timestamp at the switch port where
    the frame was received.
  - SubType = 2. Transmit timestamp response (two-step timestamping).

In addition, the length of different type switch tag is different, the
minimum length is 6 bytes, the maximum length is 14 bytes. Currently,
Forward tag, SubType 0 of To_Port tag and Subtype 0 of To_Host tag are
supported. More tags will be supported in the future.

Signed-off-by: Wei Fang <wei.fang@nxp.com>
Link: https://patch.msgid.link/20260518082506.1318236-10-wei.fang@nxp.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

This 0x88C3 is registered to Infineon Technologies Corporate Research ST
and are used by MaxLinear.
Infineon made a spin off called Lantiq.
Lantiq was acquired by Intel
MaxLinear acquired Intels Connected Home division.

The product FAQ from MaxLinear describes it's history from the F24S.
The driver for the gsw1xx is based on Lantiq showing it's similarities.

Ref https://standards-oui.ieee.org/ethertype/eth.txt

Signed-off-by: Peter Enderborg <Peter.Enderborg@axis.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support for a new DSA tagging protocol driver for the MaxLinear
GSW1xx switch family. The GSW1xx switches use a proprietary 8-byte
special tag inserted between the source MAC address and the EtherType
field to indicate the source and destination ports for frames
traversing the CPU port.

Implement the tag handling logic to insert the special tag on transmit
and parse it on receive.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Tested-by: Alexander Sverdlin <alexander.sverdlin@siemens.com>
Link: https://patch.msgid.link/0e973ebfd9433c30c96f50670da9e9449a0d98f2.1762170107.git.daniel@makrotopia.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add support for Motorcomm YT921x tags, which includes a proper
configurable ethertype field (default to 0x9988).

Signed-off-by: David Yang <mmyangfl@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20251017060859.326450-3-mmyangfl@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

- add new ETH_P_CANXL ethernet protocol type
- update skb checks for CAN XL
- add alloc_canxl_skb() which now needs a data length parameter
- introduce init_can_skb_reserve() to reduce code duplication

Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20220912170725.120748-6-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

The switch that is present on the Renesas RZ/N1 SoC uses a specific
VLAN value followed by 6 bytes which contains forwarding configuration.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Add the Ethertype for EtherCAT protocol.

Signed-off-by: Daniel Braunwarth <daniel@braunwarth.dev>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Add the Ethertype for PROFINET protocol.

Signed-off-by: Daniel Braunwarth <daniel@braunwarth.dev>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The description of ETH_P_802_3_MIN is misleading.
The value of EthernetType in Ethernet II frame is more than 0x0600,
the value of Length in 802.3 frame is less than 0x0600.

Signed-off-by: Xiayu Zhang <Xiayu.Zhang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>