A string of octets containing one bit per VLAN for VLANS
with VlanIndex values of 1024 through 2047 in the management
domain on this trunk port. The first octet corresponds to
VLANs with VlanIndex values of 1024 through 1031; the second
octet to VLANs 1032 through 1039; etc. The most significant
bit of each octet corresponds to the lowest value VlanIndex
in that octet.
If the bit corresponding to a VLAN is set to '1', then the
local switch is currently sending joins for this VLAN on
this trunk port, i.e., it is asking to receive frames for
this VLAN; if the bit is set to '0', then the local switch
is not currently sending joins for this VLAN on this trunk
port.