This object specifies the list of VLANs extended
on this Overlay interface.
It is a string of octets containing one bit per VLAN
with VlanIndex values of 2048 through 4095.
If the bit corresponding to a VLAN is set to 1,
it indicates that VLAN is being extended on this
Overlay interface.
If the bit corresponding to a VLAN is set to 0,
it indicates that VLAN is not being extended on
this Overlay interface.