OneofthemostwidelyusedroutingprotocolsinIPnetworksistheRoutingInformationProtocol(RIP)。RIPisthecanonicalexampleofaroutingprotocolbuiltonthe()algorithm.Routingprotocolsininternetworksdifferslightlyfromtheidealizedgraphmodel.Inaninternetwork,thegoaloftherouterstoforwardpacketstovarious(). RoutersrunningRIPsendtheiradvertisementaboutcostevery()seconds.Arouteralsosendsanupdatemessagewheneveranupdatefromanotherroutercausesittochangeitsroutingtable. Itispossibletousearangeofdifferentmetricsorcostsforthelinksinaroutingprotocol.RIPtakesthesimplestapproach,withalllinkcostsbeingequal(请作答此空)。Thusitalwaystriestofindtheminimumhoproute.Validdistancesare1through()ThisalsolimitsRIPtorunningonfairlysmallnetworks.
A.1 B.15 C.16 D.length of the link正确答案A
