erpsInstanceMajorRingIndex — Multiple manufacturers; see the original MIB MIB copies (LibreNMS/Observium Community), Edgecore official enterprise switch MIBs, Edgecore MIB copies (Observium Community)
An index that uniquely identifies an entry in the erpsInstanceTable. A value of 0 means this instance has no major ring. Notes: This objest can not be configured if erpsRingEastPort of associted physical ring of this instance has a vaule other than 0.