Digital Lightwave Inc. VCAT_LO_N For Nxx module - Virtual Concatenation (VCAT) test option for Low Order MappingsVC-11-Xv, VC-12-Xv, VC-2-Xv (SDH), VT-1.5-Xv, VT-2-Xv, VT-6-Xv (SONET), as per ITU G.7042; for all NGMR Interface rates from 155M to 10G