edgerouter-x DSA switch does not forward bridge-in-bridge packets correctly

Fabian Bläse fabian at blaese.de
Sun Aug 29 13:59:46 PDT 2021

On 29.08.21 22:44, Michael Richardson wrote:
> Fabian Bläse <fabian at blaese.de> wrote:
> > Frames between untagged ports (e.g. eth0 and eth1) are forwarded
> > correctly and frames between tagged ports (eg. eth3 and eth4) are
> > forwarded correctly.
> It sounds like the hardware bridge expects the host to do the bridging
> between tagged and untagged ports.  That's my guess.
That should not be the case. The hardware is capable of forwarding frames between tagged and untagged ports.
Judging by the forwarding speed, this works correctly with regular single-bridge configurations.

> > Also, tagged frames are incorrectly forwarded on untagged ports, so it
> > is possible to reach a device connected to eth3 (tagged) on eth2
> > (tagged).
> This is rather concerning.
> It sounds like the hardware bridge is completely unaware of the tagging.
Sounds a bit like it. However, not all ports did forward frames equally iirc.
But that is exactly what I would expect, if I understand the upstream patch correctly, which supposedly fixes the problem (see my other replies to this thread and my pull request [1]).

> > This issue does not appear, if the 'bridge1.4' interface is configured
> > without an additional bridge, so the second bridge seems to be
> > interfering with the hardware offloading.
> Why do you configure this with two layers of bridge?
> I think that bridge1 is hardware offloaded, right?
For convenience. Otherwise it would be necessary to configure bridge-vlans for the wireless interfaces.

Also, it simplifies our downstream configuration.
The configuration with multiple bridges allows it to treat DSA devices more-or-less like swconfig devices.

Best regards,

[1] https://github.com/openwrt/openwrt/pull/4493

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