7 6 5 4 3 2 1 0
+-+-+-+-+-+-+-+-+
|SHT|       |RED|
+-+-+-+-+-+-+-+-+
RED = "Multihoming Redundancy Mode" field (see Table 2)

SHT bit 7 6
-----------
        0 0  --> Default SHT 
                 Backwards compatible with [RFC8365] and [RFC7432]
        0 1  --> Local Bias
        1 0  --> ESI Label-based filtering
        1 1  --> Unassigned