When i create a dummy network interface and then bring it up it show up being in UNKNOWN state:
root@5b8dd2855a9c:# ip l a boom type dummy
root@5b8dd2855a9c:# ip l show boom
58: boom: <BROADCAST,NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT
link/ether 1e:f6:4b:60:ff:1a brd ff:ff:ff:ff:ff:ff
root@5b8dd2855a9c:# ip l set boom up
root@5b8dd2855a9c:# ip l show boom
58: boom: <BROADCAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc noqueue state **UNKNOWN** mode DEFAULT
link/ether 1e:f6:4b:60:ff:1a brd ff:ff:ff:ff:ff:ff
root@5b8dd2855a9c:#
Anyone knows why ? I tried assigning an IP address to it, but that did not resolve the issue.
I tested this on the following machine:
root@5b8dd2855a9c:# uname -a
Linux 5b8dd2855a9c 3.16.1-tinycore64 #1 SMP Fri Aug 22 05:53:09 UTC 2014 x86_64 GNU/Linux
root@5b8dd2855a9c:#
Update:
So it seems that this does not make the interface inoperable. After some slavish Googling I came across this info