Re: ifconfig(8) - a tale of two states

[Jason Thorpe <thorpej%me.com@localhost>]

> On Oct 7, 2020, at 8:20 AM, Greg Troxel <gdt%lexort.com@localhost> wrote:
> 
> It may be that with 10base2, "UP" means "cable is terminated properly".
> Or perhaps it's NA.

Plenty of old school Ethernet controllers were capable of reporting if carrier was present on 10base2 / 10base5.  Carrier present == UP, carrier not present == DOWN, controller can't tell either way == NA or UNKNOWN (although you still want to be able to use the interface, so UNKNOWN doesn't really seem right).

-- thorpej