The netgraph node paths cannot contain '.' and ':' characters, so the ng_ether module sanitizes interface names containing them (like the new format for vlans, eg. fxp0.1) by replacing illegal characters with underscores. This patch keeps interface name and netgraph path separated in the pppoe layer so that mpd can be used successfully on vlan interfaces.
iface = fxp0.1
path = fxp0_1:
Moreover I've added basic support to display PADM messages, introduced by the following patch: https://reviews.freebsd.org/D9270