An instance of this object only exists when the
local VCL end-point is also the VCC end-point,
and AAL is in use.
The type of AAL used on this VCC.
The AAL type includes AAL1, AAL2, AAL3/4,
and AAL5. The other(4) may be user-defined
AAL type. The unknown type indicates that
the AAL type cannot be determined.