TRILL (TRansparent Interconnection of Lots of Links) Data frames can
be encoded so as to make more efficient use of communications links
under certain circumstances. This document specifies two such
optional optimizations. One, called Compact Format, improves the
compactness of encoding where a TRILL link is a point-to-point
Ethernet link. The other, called Specific Addressing, optionally
decreases the burden on multi-access TRILL links for multi-
destination TRILL Data frames. This document updates RFC 6325.