Subnet directed broadcasts A principal limitation of standard broadcast Wake-on-LAN is that broadcast packets are generally not routed. This prevents the technique being used in larger networks or over the Internet. Subnet-directed broadcasts (SDBs) may be used to overcome this limitation. SDB may require changes to the intermediate router configuration. SDBs are treated like unicast network packets until processed by the final (local) router. This router then broadcasts the packet using a layer-2 broadcast. This technique allows a broadcast to be initiated on a remote network but requires all intervening routers to forward the SDB. When preparing a network to forward SDB packets, care must be taken to filter packets so that only desired (e.g. WoL) SDB packets are permittedotherwise the network may become a participant in DDoS attacks such as the Smurf attack.
subnEt dIReCtED bRoadCasts a PriNcipal LimitaTIOn of stanDard brOaDcAst wake-ON-laN is that BrOAdCAst Packets aRe gEneraLly not ROuTED. ThiS prevEnts the teChniqUe beiNg used In LaRGer NetWorks or over tHE IntErnet. sUbnet-diRectEd BroADcaSts (sdbS) may be used to overcoME tHis limitation. sdb MAY reqUIrE changeS TO The IntErmEdiATe rOUTer cOnFiguRatiOn. sDbs arE tREATed liKe uNiCAst neTWorK packets untIl procESsEd by thE final (lOcal) router. thIS rOuTEr then broAdcAstS the pAcket using a layeR-2 bRoadCAst. this technIqUe AlLowS a BroAdcAst TO BE iniTIatEd On A reMote netwOrk but RequIrEs all InterVeniNg roUtErs tO forwaRD the sDb. when PreParInG a netwOrK to FoRWArd sDb paCKETs, care muSt BE taKen to filter pAckETS So ThAt ONLY deSIrEd (E.g. wol) sdb paCkeTS aRe perMiTteDOtHerwiSE the nEtwORK MAY beCome a paRtiCiPant In Ddos attAcks Such as the smurF aTtacK.