Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Principles for QOS Guarantees Consider a phone application at 1Mbps and an FTP application sharing a 1.5 Mbps link. bursts of FTP can congest the router and cause audio packets to be dropped. want to give priority to audio over FTP PRINCIPLE 1:Marking of packets is needed for router to distinguish between different classes;and new router policy to treat packets accordingly 1 Mbps H1 R1 1.5 Mbps R2 H2 H4 2616009:Network Traffic Engineering 7:IntServ and DiffServ Page.42616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 7: IntServ and DiffServ Page.4 Principles for QOS Guarantees • Consider a phone application at 1Mbps and an FTP application sharing a 1.5 Mbps link. - bursts of FTP can congest the router and cause audio packets to be dropped. - want to give priority to audio over FTP • PRINCIPLE 1: Marking of packets is needed for router to distinguish between different classes; and new router policy to treat packets accordingly