Networkscanbeinterconnectedbydifferentdevicesinthephysicallayernetworkscanbeconnectedby(请作答此空)_orhubs.whichjustmovethebitsfromonenetworktoanidenticalnetwork.Onelayerupwefindbridgesandswitcheswhichoperateatdatalinklayer.Theycanaccept()examinetheMACaddressandforwardtheframestoadifferentnetworkwhiledoingminorprotocoltranslationintheprocessinmenetworklayer,wehaveroutersthatcanconnecttwonetworks,Iftwonetworkshave()networklayer,theroutermaybeabletotranslatebetweenthepackerformats.Inthetransportlayerwefindtransportgateway,whichcaninterfacebetweentwotransportconnectionsFinally,intheapplicationlayer,applicationgatewaystranslatemessage().Asanexample,gatewaysbetweenInternete-mailandX.400e-mailmust()thee-mailmessageandchangevariousheaderfields.
A.reapers B.relays C.packages D.modems正确答案A
