An entry in the atDHCPportRuleTable. Each entry in this table
identifies exactly one port that is part of the VLAN
definition. Hence all the entries of this table with the same
GroupId and VLANId collectively define one VLAN which is based
on a Port Rule.
A specific port can be included in definition of more than one
vlan as long as those two vlans are part of the same VLAN group.
That is to say, a port can belong to more than one vlan but can
be part of atmost one VLAN group.