Vladimir Oltean

Yeah. I mean, they look horrible in tcpdump, but it gets the job done. ``` root@debian:~# tcpdump -i end0 -e -n -XX tcpdump: verbose output suppressed, use -v[v]... for full...

They are absolutely Ethernet frames with an extra header (generically called "tag" because depending on switch vendor, it may not actually be "header" but also "trailer") that contains switch-specific information....

No, it's not one of the 4 protocols for which libpcap assigns a specific link type, but rather one of the remaining 25 for which it doesn't. https://elixir.bootlin.com/linux/v6.13.2/source/include/net/dsa.h#L58 Mostly nobody...

I mean, they _are_ Ethernet packets, and comply to all Ethernet packet rules. The host port (which is most of the time a regular, DSA-unaware network card, and which any...

So when I said that the host port is "most of the time a regular, DSA-unaware network card", I really selected my words carefully by saying "most of the time",...

> And if, in fact, that's the case, then we don't need LINKTYPE_DSA_TAG_xxx types for anything other than prepend or trailer types, as tcpdump, Wireshark, etc. can just use the...

> However, if a DSA tag type is ever used for on-the-wire Ethernet traffic, a LINKTYPE_ value is needed. I think there might be places where it is, but maybe...

> Currently: > we have LINKTYPE_/DLT_ values for "brcm", "brcm-prepend", "dsa", and "edsa", which is as it should be, as they're either type 1 or type 2 without a usable...

Ok, but confusingly you refer to type 2 tags with no usable EtherType as if there was any tag at all whose EtherType is in the IANA 802 numbers table....

Here's what I've been able to extract from the kernel sources. | proto | type | length (bytes) | xmit format | rcv format | | ------------ | ---------------- |...