Subnet-based vlan port table.
Add all subnet on vlan whose vlan id is h3cSubnetVlanPortInfoVlanId
into port at a draught.
All of the subnet information in this port is from the h3cSubnetVlanTable
above, with the value of h3cSubnetVlanPortInfoVlanId as an index,
which is h3cSubnetVlanVlanId in h3cSubnetVlanTable.