Description: If the value of this object is 'bidirectional(0)', then the LSR supports the use of a given DLCI as a label for both directions independently. If the value of this object is 'unidirectional(1)', then the LSR uses the given DLCI as a label in only one direction.

This is the EXACT value for the Frame Relay Session Parameter, field D (for VC Directionality). The Frame Relay Session Parameter is an optional parameter in the Initialization Message.

The description from rfc3036.txt is:

'D, VC Directionality A value of 0 specifies bidirectional VC capability, meaning the LSR can support the use of a given DLCI as a label for both link directions independently. A value of 1 specifies unidirectional VC capability, meaning a given DLCI may appear in a label mapping for one direction on the link only. When either or both of the peers specifies unidirectional VC capability, both LSRs use unidirectional VC label assignment for the link as follows. The LSRs compare their LDP Identifiers as unsigned integers. The LSR with the larger LDP Identifier may assign only odd-numbered DLCIs in the range as labels. The system with the smaller LDP Identifier may assign only even-numbered DLCIs in the range as labels.'

Please refer to the following reference for a complete description of this feature.