This object indicates the VLAN types that this
bridge will support. Open mode means that each VLAN
within this bridge will be of the Open type; all VLANs
within this bridge will share the same address table.
Closed mode means that each VLAN within this bridge
will be of the Closed type; each VLAN within this
bridge will have its own address table. Mixed mode
means that each VLAN within this bridge with be of
either the Open or Closed type; all Open VLANs will
share the same address table and each Closed VLAN
will have its own address table.