> Could you elaborate what protocols and products are in need of this > functionality? The ones I'm aware of are: (a) Google's servers (b) Android on at least some chipsets (Qualcomm at the bare minimum, but I think it's pretty standard a solution) where there's a complex port sharing scheme between the Linux kernel on the Application Processor and the Firmware running on the modem (for ipv4 we only get one ip address from the cellular carrier). It's basically required for things like wifi calling to work. > Why can't the NIC just get its own IP like it usually does with NCSI? Because often these nics are deployed as in place upgrades in environments where there's a limited number of IPs. Say a rack with a /27 ipv4 subnet (2**5 = 32 -> 29 usable ips, since network/broadcast/gateway are burned) and 15+ pre-existing machines. This means there's not enough IPs to assign separate ones for the nics. Renumbering the rack, would imply renumbering the datacenter, etc... And ipv4 - even RFC1918 - has long run out - so even in new deployments there's not enough IPv4 ips to give to nics, and IPv6 isn't yet deployed *everywhere*.
