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Linus Lüssing 64ad16993d realtek: fix flooding of unsnoopable multicast addresses
RFC4541, section 2.1.2 says:

  Packets with a destination IP (DIP) address in the 224.0.0.X range
  which are not IGMP must be forwarded on all ports.

And section 3 says:

  In IPv6, the data forwarding rules are more straight forward because
  MLD is mandated for addresses with scope 2 (link-scope) or greater.
  The only exception is the address FF02::1 which is the all hosts
  link-scope address for which MLD messages are never sent.  Packets
  with the all hosts link-scope address should be forwarded on all
  ports.

However, currently when a listener on FF12::1 or FF12:🔢0:1 for
example joins then not only packets to these addresses but also for
FF02::1 won't be flooded to all ports anymore, too. Which violates
RFC4541.

This happens because A): They all map to the same ethernet multicast
address, that is 33:33:00:00:00:01. And B) the VLAN profile L2
unknown MC flood setting will only apply flooding of 33:33:00:00:00:01
if there is no specific listener registered for it.

So to fix this, avoid registering an MDB entry in the switch for
33:33:00:00:00:01 at all.

The downside of this is that FF12::1, FF12:🔢0:1 etc.
will always be flooded, too. However fixing the handling of 224.0.0.X
and FF02::1 and adhering to RFC4541 must have priority to avoid
undesired packetloss, to avoid breaking IPv4/IPv6.

Tested-on: ZyXEL GS1900-24HP v1

Fixes: cde31976e3 ("realtek: Add support for Layer 2 Multicast")
Signed-off-by: Linus Lüssing <linus.luessing@c0d3.blue>
Link: https://github.com/openwrt/openwrt/pull/18769
Signed-off-by: Robert Marko <robimarko@gmail.com>
2025-05-15 19:01:22 +02:00
.devcontainer/ci-env devcontainer: Add development environment for gihub codespace 2023-10-30 23:34:26 +01:00
.github CI: labeler: Add qualcommbe target 2025-02-09 21:04:19 +01:00
.vscode meta: VS Code: add "Git: Always Sign Off" setting 2024-10-03 17:18:51 +02:00
config kernel: add KERNEL_ARM64_CONTPTE 2025-05-10 07:58:12 +02:00
include cmake: use RelWithDebInfo, not Debug, with CONFIG_DEBUG 2025-05-10 12:41:26 +02:00
LICENSES LICENSES: include all used licenses in LICENSES directory 2021-02-14 19:21:38 +01:00
package kernel: package intel_vpu driver 2025-05-15 10:09:40 +02:00
scripts imagebuilder: exclude metadata for profiles that have no kernel 2025-05-09 11:06:57 +02:00
target realtek: fix flooding of unsnoopable multicast addresses 2025-05-15 19:01:22 +02:00
toolchain toolchain: gcc: backport patch to fix ICE with PowerPC targets 2025-05-14 11:23:34 +02:00
tools tools/llvm-bpf: fix compilation with GCC15 2025-05-10 12:39:31 +02:00
.gitattributes .gitattributes: ignore some whitespace "violations" in .patch files 2024-12-12 11:01:56 +01:00
.gitignore gitignore: ignore local APK keys 2024-05-17 22:03:06 +03:00
BSDmakefile build: use SPDX license tags 2021-02-05 14:54:47 +01:00
Config.in build: scripts/config - update to kconfig-v5.14 2022-02-19 13:10:01 +01:00
COPYING COPYING: add COPYING file to specify project licenses 2021-02-14 19:21:38 +01:00
feeds.conf.default feeds.conf.default: enable video feed by default 2024-12-05 01:34:01 +00:00
Makefile build: include tests/Makefile if available 2024-06-17 17:51:31 +02:00
README.md README: replace "MacOSX" with "macOS" 2024-04-01 18:46:30 +02:00
rules.mk tools: add options to optimize host binaries 2025-05-04 18:25:03 +02:00

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