vRtrIfEncapValue

The value of the label used to identify the entity using the
specified encapsulation value on a specific port.
          
The format of this object depends on the encapsulation type
defined on this port.
          
When the encapsulation is nullEncap the value of this object
must be zero.
          
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 00000000 00000000|
+--------+--------+--------+--------+
          
When the encapsulation is dot1qEncap the value of this object
is equal to the 12-bit IEEE 802.1Q VLAN ID.
          
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is mplsEncap the value of this object
is equal to the 20-bit LSP ID.
          
31                                   0
+--------+--------+--------+--------+
|00000000 0000XXXX XXXXXXXX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is frEncap, the value of this object is
equal to the 10-bit Frame Relay DLCI.
          
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 000000XX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is qinqEncap, the value of the outer
802.1Q VLAN ID is encoded in the least significant 16 bits,
and the value of the inner VLAN ID is encoded in the most
significant 16 bits.
          
31                                   0
+--------+--------+--------+--------+
|0000YYYY YYYYYYYY 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+
          
When the encapsulation is atmEncap, the value
of the ATM VCI is encoded in the least significant 
16 bits, and the value of the ATM VPI is encoded 
in the next 12 bits.
          
For ATM VCs, the top 2 bits are 00.  The value of
the ATM VCI is encoded in the least significant 16 
bits, and the value of the ATM VPI is encoded in the next
12 bits.
                        
31                                   0
+--------+--------+--------+--------+
|0000YYYY YYYYYYYY XXXXXXXX XXXXXXXX|
+--------+--------+--------+--------+   
          
For ATM VPs, the top 2 bits are 01.  The value of
the ATM VPI is encoded in the least significant 12 bits.
          
31                                   0
+--------+--------+--------+--------+
|01000000 00000000 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+          
          
For ATM VP ranges, the top 2 bits are 10.  The value of
the start of the ATM VPI range is encoded in the least significant 
12 bits, and the value of the end of the ATM VP range is encoded
in the next 12 bits.
          
31                                   0
+--------+--------+--------+--------+
|10000000 YYYYYYYY YYYYXXXX XXXXXXXX|
+--------+--------+--------+--------+         
          
For ATM ports, the top 2 bits are 11, and the rest of the bits 
must be zero.  
          
31                                   0
+--------+--------+--------+--------+
|11000000 00000000 00000000 00000000|
+--------+--------+--------+--------+         
          
When the encapsulation is wanMirrorEncap the value of this 
object is equal to the 12-bit value.
                        
31                                   0
+--------+--------+--------+--------+
|00000000 00000000 0000XXXX XXXXXXXX|
+--------+--------+--------+--------+      
          
Some ports have a restrictions to the encapsulation types that
they can support and hence impose restrictions on the respective
formats defined above.