Re: Requesting DLT_* values for Ethernet switches proprietary tagging protocol

[Guy Harris <gharris () sonic net>]

On Jan 17, 2019, at 6:01 PM, Florian Fainelli <f.fainelli () gmail com> wrote:

> Correct. The other ports are exposed as regular Ethernet network devices.

OK, I've updated a comment in the pull request for that.

So, in any pre-4.19 kernels, does the directory /sys/class/net/{device}/dsa exist even if there's no tagging file in 
that directory?

Or is there some other way, in pre-4.19 kernels, to determine if a NIC is a DSA management-port NIC?

If so, then, even though you can't determine the tag type from userland, you could offer all the DLT_s for the various 
tag types in the DLT list and let the user choose which one to use; they might be able to do so if they know what type 
of device they're capturing on.  (If the tagging file *does* exist, you can just offer them the one DLT_ that's correct 
for the device.)
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