Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 ATM Forum BE subclasses Available Bit Rate (ABR) users get whatever is available zero loss if network signals (in RM cells)are obeyed no guarantee on delay or bandwidth 。 Unspecified Bit Rate (UBR) like ABR.but no feedback no guarantee on loss presumably cheaper 2616009:Network Traffic Engineering 8:Traffic Management and Modeling Page.26
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 8: Traffic Management and Modeling Page.26 ATM Forum BE subclasses • Available Bit Rate (ABR) - users get whatever is available - zero loss if network signals (in RM cells) are obeyed - no guarantee on delay or bandwidth • Unspecified Bit Rate (UBR) - like ABR, but no feedback - no guarantee on loss - presumably cheaper
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 IETF GS subclasses ·Tolerant GS nominal mean delay,but can tolerate occasional?variation not specified what this means exactly uses controlled-load service s book uses older terminology (predictive) - even at high loads?admission control assures a source that its service does not suffer it really is this imprecise! ·Intolerant GS need a worst case delay bound - equivalent to CBR+VBR in ATM Forum model 2616009:Network Traffic Engineering 8:Traffic Management and Modeling Page.27
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 8: Traffic Management and Modeling Page.27 IETF GS subclasses • Tolerant GS - nominal mean delay, but can tolerate occasional?variation - not specified what this means exactly - uses controlled-load service § book uses older terminology (predictive) - even at high loads? admission control assures a source that its service does not suffer - it really is this imprecise! • Intolerant GS - need a worst case delay bound - equivalent to CBR+VBR in ATM Forum model
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 IETF BE subclasses ·Interactive burst bounded asynchronous service,where bound is qualitative,but pretty tight s e.g.paging,messaging,email Interactive bulk bulk,but a human is waiting for the result e.g.FTP ·Asynchronous bulk junk traffic -e.g netnews 2616009:Network Traffic Engineering 8:Traffic Management and Modeling Page.28
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 8: Traffic Management and Modeling Page.28 IETF BE subclasses • Interactive burst - bounded asynchronous service, where bound is qualitative, but pretty tight § e.g. paging, messaging, email • Interactive bulk - bulk, but a human is waiting for the result - e.g. FTP • Asynchronous bulk - junk traffic - e.g netnews
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Some points to ponder The only thing out there is CBR and asynchronous bulk! These are application requirements.There are also organizational requirements(link sharing) Users needs QoS for other things too! billing privacy reliability and availability 2616009:Network Traffic Engineering 8:Traffic Management and Modeling Page.29
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 8: Traffic Management and Modeling Page.29 Some points to ponder • The only thing out there is CBR and asynchronous bulk! • These are application requirements. There are also organizational requirements (link sharing) • Users needs QoS for other things too! - billing - privacy - reliability and availability
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Examples of traffic source behaviour Constant bit rate (e.g.voice) A periodic stream of packets whose period is the quotient of the effective line rate divided by the source rate,e.g. 53 bytes long 口 口 口 note:effective line rate =(48/53)"line rate effective line rate/source rate Note:strict periodicity can be altered as packet stream proceeds across network due to random queueing delays introducing jitter. important parameters: mean packet rate=peak packet rate 2616009:Network Traffic Engineering 8:Traffic Management and Modeling Page.30
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 8: Traffic Management and Modeling Page.30 Examples of traffic source behaviour • Constant bit rate (e.g. voice) - A periodic stream of packets whose period is the quotient of the effective line rate divided by the source rate, e.g. Note: strict periodicity can be altered as packet stream proceeds across network due to random queueing delays introducing jitter. • important parameters: - mean packet rate=peak packet rate effective line rate/source rate 53 bytes long note: effective line rate =(48/53)*line rate