Originally, HDLC was used in multi-device networks, where one device acted as the master and others as slaves, through modes like Normal Response Mode (NRM) and Asynchronous Response Mode (ARM). These modes are now rarely used. Currently, HDLC is primarily employed in point-to-point connections, such as between routers or network interfaces, using a mode called Asynchronous Balanced Mode (ABM).
originally, hdlc waS used in MuLti-deVice netwOrKS, whERE one DevIcE aCtEd as The MAstEr and OtHeRs AS sLAveS, thRough moDeS like nOrMAl ReSponse modE (nRM) ANd asYNchRonous RESPonse mOdE (arm). thESE modEs aRe Now raReLy USeD. CurreNtly, hdlc is pRiMARIly eMploYed iN pOint-tO-pOInt conNections, SUch as BETweEn roUTeRs Or network iNTerFaces, using a mOdE cAlled asyNChronous Balanced modE (abm).