QoS Models

o   Define how we deal with Contention in network

o   Two Types

§  Integrated Services

§  Differentiated Services

o   Both are defined by different RFCs

o   Integrated Services( IntServ)

§  Every application flow has an explicit reservation end-to-end network

§  It is connection oriented type-2 ios model

·         Application has awareness about QoS of end-to-end network

§   Does not scale well

·         Network must maintain too much state

·         Generally routers want to maintain in less state

§    It is a legacy IOS QoS model

§  Still used in real world applications

·         Mainly in MPLS traffic engineering(129^th video, 7^th minute)

o   Differentiated Services (DiffServ)

§  They are well known PHBs (Per Hop Basis)