Bandwidth for High Speed Networks

In comparison fred performs signi cantly worse though

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Unformatted text preview: y well, although not quite as well as DRR. In the second experiment we replace UDP-0 with a TCP ow. Similarly, Figure 6b plots the normalized TCP throughput against the number of congested links. Again, DRR and CSFQ prove to be e ective. In comparison, FRED performs signi cantly worse though still much better than RED and FIFO. The reason is that while DRR and CSFQ try to allocate bandwidth fairly among competing ows during congestion, FRED tries to allocate bu ers fairly. Flows with different end-to-end congestion control algorithms will achieve di erent throughputs even if routers try to fairly allocate bu er. DRR CSFQ FRED RED FIFO 1.4 1.2 Allocated Bwdth. / Ideal Bwdth. 1.2 Allocated Bwdth. / Ideal Bwdth. DRR CSFQ FRED RED FIFO 1.4 1 0.8 0.6 1 0.8 0.6 0.4 0.4 0.2 0.2 0 0 1 1.5 2 2.5 3 3.5 Number of Congested Links 4 4.5 5 a 1 1.5 2 2.5 3 3.5 Number of Congested Links 4 4.5 5 b Figure 6: a The normalized throughput of UDP-0 as a function of the number of congested links. b The same plot when UDP-0 is replaced by a TCP ow. Algorithm delivered dropped DRR 601 6157 CSFQ 1680 5078 FRED 1714 5044 RED 5322 1436 FIFO 5452 1306 Algorithm mean std. dev DRR 6080 64 CSFQ 5761 220 FRED 4974 190 RED 628 80 FIFO 378 69 Table 1: Statistics for an ON-OFF ow with 19 competing TCPs ows all numbers are in packets. Table 3: The mean throughputs in packets and standard deviations for 19 TCPs in the presence of a UDP ow along a link with propagation delay of 100 ms. The UDP sends at the link capacity of 10 Mbps. Algorithm mean time std. dev DRR 25 99 CSFQ 62 142 FRED 40 174 RED 592 1274 FIFO 840 1695 Table 2: The mean transfer times in ms and the corresponding standard deviations for 60 short TCPs in the presence of a UDP ow that sends at the link capacity, i.e., 10 Mbps. 3.3 Coexistence of Di erent Adaptation Schemes In this experiment we investigate the extent to which CSFQ can deal with ows that employ di erent adaptation schemes. Receiver-driven Layered Multicast RLM 15 is an adaptive scheme in which the source sends the inform...
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This document was uploaded on 03/04/2014 for the course ENG 531 at Rice.

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