The value of tmnxMcRingNodeRncvEncapValue specifies the encapsulation
value of the SAP used for the Ring-Node Connectivity Verification
of this ring node.
It is only meaningful if the value of tmnxMcRingNodeRncvSvcId is not
zero.
The value zero means that the SAP used for the Ring-Node Connectivity
Verification of this ring node uses NULL encapsulation.