header types
-----------------
type 1			00	One byte header, one 10 byte address field
type 2			01	One byte header, two 10 byte address fields
type 3			10	Reserved
type 4			11	Reserved for extended header format


propagation types
-----------------
broadcast		00
transport		01
relay			10
tunnel			11


destination types
-----------------
single			00
group			01
plain			10
link			11


packet types
-----------------
resource		00
announce		01
link request	10
proof			11