An entry in this table is created for every MVRF for which
a default MDT group is configured. A MVRF which does not
have a default MDT group configured will not appear in
this table.
Creation of a row in this table is the equivalent of
configuring default MDT address for the given MVRF.
Deletion of a row in this table is the equivalent of
deconfiguring default MDT address for the given MVRF.