CFM-Connectivity Fault managment
MEP-Maintenenace End point
DOWNMEP-In an interface , if CFM Frames passes without processing through the bridge relay entity.Then the interfaces end point should be configured Down MEP.
UP MEP:In an interface , if CFM Frames are processed by the bridge relay entity .The the interfaces end points should be configured as UP MEP.
From the image it can be seen that,
Downmep is the endpoint to the wireside where no processing of the cfm frames is involved.(Green Inverted triangle).
Upmep is the endpoint and it forwards cfm frames through the bridge relay entity.(Blue upright triangle).