Description: The mapping protocols (internally considered as
the 'link type') applied on this circuit.
The value ranges from 0 to 2047.
For point-to-point DLCI, the value stays zero.
Otherwise, the value is a sum. It initially takes
the value zero, then, for each type of Protocol,
2 raised to a power is added to the sum.
The following table presents respective power and
equivalent value for each applicable type:

        Protocol        Power    Value
        --------        -----    -----
        IP              0        1
        IPX             1        2
        Appletalk       2        4
        XNS             3        8
        VINES           4        16
        DECnet          5        32
        CLNS            6        64
        Bridging        7        128
        RSRB            8        256
        STUN            9        512
        LLC2            10       1024

For example, value 3 means the circuit's mapping
protocols include IP and IPX. (3 = 2**1 + 2**0,
where 0 corresponds to IP and 1 to IPX.) Value 0
means there is currently no mapping protocol for
the circuit.
See cfrMapTable for more mapping information.