Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Unit 5 Buffer Management 2616009:Network Traffic Engineering 5:Buffer Management Page.1
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.1 Unit 5 Buffer Management
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Outline Why packet drop 。 Classification of drop strategies 。】 IP Active Queue Management(AQM) RED FRED BLUE -RIO Case study:Performance of Selective Discard 2616009:Network Traffic Engineering 5:Buffer Management Page.2
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.2 Outline • Why packet drop • Classification of drop strategies • IP Active Queue Management(AQM) - RED - FRED - BLUE - RIO • Case study: Performance of Selective Discard
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Packet dropping 。 Packets that cannot be served immediately are buffered Full buffers =packet drop strategy Packet losses happen almost always from best-effort connections (why?) Shouldn't drop packets unless imperative packet drop wastes resources(why?) 2616009:Network Traffic Engineering 5:Buffer Management Page.3
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.3 Packet dropping • Packets that cannot be served immediately are buffered • Full buffers => packet drop strategy • Packet losses happen almost always from best-effort connections (why?) • Shouldn’t drop packets unless imperative – packet drop wastes resources (why?)
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Classification of drop strategies Degree of aggregation Drop priorities Early or late Drop position 2616009:Network Traffic Engineering 5:Buffer Management Page.4
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.4 Classification of drop strategies • Degree of aggregation • Drop priorities • Early or late • Drop position
Feng Gang National Laboratory of Communication,UESTC Aug 2017 Ver 1.4 Degree of aggregation Degree of discrimination in selecting a packet to drop E.g.in vanilla FIFO,all packets are in the same class Instead,can classify packets and drop packets selectively The finer the classification the better the protection Max-min fair allocation of buffers to classes drop packet from class with the longest queue(why?) 2616009:Network Traffic Engineering 5:Buffer Management Page.5
2616009: Network Traffic Engineering Feng Gang National Laboratory of Communication, UESTC Aug 2017 Ver 1.4 5: Buffer Management Page.5 Degree of aggregation • Degree of discrimination in selecting a packet to drop • E.g. in vanilla FIFO, all packets are in the same class • Instead, can classify packets and drop packets selectively • The finer the classification the better the protection • Max-min fair allocation of buffers to classes - drop packet from class with the longest queue (why?)