Re: [PATCH RFC net-next 0/3] Multi-CPU DSA support

Will DSA assume that all CPU ports are equal in terms of tagging
protocol abilities? There are switches where one of the CPU ports can
do tagging and the other can't.

Hi Vladimir

Given the current definition of what a CPU port is, we have to assume
the port is using tags. Frames have to be directed out a specific
egress port, otherwise things like BPDU, PTP will break. You cannot
rely on MAC address learning.

Is the static assignment between slave and CPU ports going to be the
only use case? What about link aggregation? Flow steering perhaps?
And like Andrew pointed out, how do you handle the receive case? What
happens to flooded frames, will the switch send them to both CPU
interfaces, and get received twice in Linux? How do you prevent that?

I expect bad things will happen if frames are flooded to multiple CPU
ports. For this to work, the whole switch design needs to support
multiple CPU ports. I doubt this will work on any old switch.

Having a host interface connected to a user port of the switch is a
completely different uses case, and not what this patchset is about.

	   Andrew