ABSTRACT
Nowadays, almost any industrial network uses applications based on IP networks [1]. ¥is means that peoplecontrollingthesenetworksneedtoknowatleastthebasicsofqualityofservice(QoS)forIPnetworks.EverydeviceusedinanindustrialnetworkisgoingtosendandreceiveIPpacketsbut,depending onthenatureoftheindustrialapplicationweuseinthedevice,thewaytoprocesstheIPpacketscanbe decisivetotheobjectiveswewanttogetthroughthedevice.¥eIPnetworkisthefundamentalinfrastructureforeveryindustrialnetworkso,althoughwecannotchangethedetailsoftheIPimplementationintheoperatingsystemsofthedevices,weneedtoknowhowtogetthemaximumperformance andreliabilityofournetworkforeveryindustrialapplicationwedecidetouse.Itisalsoimportantto notethatthedeviceswecanusetomanageandimplementtheseQoScharacteristicsarenotthesame devicesweusetoimplementourindustrialapplicationsbuttheusualcommunicationdevicesinevery IPnetwork-switchesandrouters.ItissopossibletosaythattheQoSrequirementsinindustrialnetworksdependontheindustrialapplicationswewanttouseand,asaconsequence,ofthecomplexity ofthenetwork.Ifthenetworkusesrouters,wecanapplyspecialfeaturesintherouterstoimproveour QoS; but if the network only needs switches, we can only use a restricted set of QoS features.
