The value of the Device Identifier variable in the Vendor
Identifier field (see Table 57-9) of the most recently
sent Information OAMPDU.
This value is updated on reception of a valid frame, with
(1) destinationField equal to the reserved multicast
address for Slow_Protocols specified in CROSS REF Table
43B-1, (2) lengthOrType field value equal to the reserved
Type for Slow_Protocols as specified in CROSS REF Table
43B-2, (3) a Slow_Protocols subtype value equal to the
subtype reserved for OAM as specified in Table 43B-3, (4)
a OAMPDU code equal to the Information code as specified
in Table 57-4.