Get the current received quality of port. The meanings of the values are: prs(1) - PRS traceable (ITU-T G.811); prc(2) - Primary reference clock; stu(3) - Synchronized Ƀ Traceability unknown; ssua(4) - Type I or V slave clock defined in ITU-T G.812; tnc(5) - Traceable to transit node clock (ITU-T G.812, type V); st2(6) - Traceable to stratum 2 (ITU-T G.812, type II); ssub(7) - Type VI slave clock defined in ITU-T G.812; eec2(8) - EEC2 clock or st3 clock; eec1(9) - EEC1 clock or SEC clock; smc(10) - Traceable to SONET clock self timed; st3e(11) - Traceable to stratum 3E (ITU-T G.812, type III); prov(12) - Provisionable by the network operator; dnu(13) - Do not use this quality; dus(14) - Do not use for synchronization; na(15) - N/A(not receive)