Traffic Management for the Available Bit Rate (ABR) Service in ...
Traffic Management for the Available Bit Rate (ABR) Service in ... Traffic Management for the Available Bit Rate (ABR) Service in ...
Rates Rates 2five-sources.r/option=8485/optionb1=359/icr=1.0/time_int=200.0/sw_int=30/share=0.999/dist=1000/cif=4096/xdf=0.5/tof=2.0/rttq=1.0/tcr=10.0/trm=100000.0 tdf1=0.0/headroom=1.0/t_threshold=200000.0/maxsrcrate=10.0/HA=1.0/mib=20000/mib=20000/vbrrate=124.41/t0v=120/a=1.15/b=1.05/qlt=0.8 / Date:11/20/95 ICR: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 / XRM: 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 / Graph: 2 180 160 140 120 100 80 60 40 20 Five Sources ACR for S1 Source Rate for S1 ACR for S2 ACR for S3 ACR for S4 ACR for S5 0 0 50 100 150 200 250 Time in milliseconds 300 350 400 (a) No UILI Rates Rates 2five-sources.r/option=8485/optionb=79/icr=1.0/time_int=200.0/sw_int=30/share=0.999/dist=1000/cif=4096/xdf=0.5/tof=2.0/rttq=1.0/tcr=10.0/trm=100000.0 tdff=0.125/headroom=1.0/t_threshold=200000.0/maxsrcrate=10.0/HA=1.0/mib=20000/mib=20000/vbrrate=124.41/t0v=120/a=1.15/b=1.05/qlt=0.8 / Date:11/20/95 ICR: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 / XRM: 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 / Graph: 1 180 160 140 120 100 ICR: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 / XRM: 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 / Graph: 2 80 60 40 20 Five Sources ACR for S1 Source Rate for S1 ACR for S2 ACR for S3 ACR for S4 ACR for S5 0 0 50 100 150 200 250 Time in milliseconds 300 350 400 (b) Aug 1995 UILI 2five-sources.r/option=8485/optionb=71/icr=1.0/time_int=200.0/sw_int=30/share=0.999/dist=1000/cif=4096/xdf=0.5/tof=2.0/rttq=1.0/tcr=10.0/trm=100000.0 tdf=0.125/headroom=1.0/t_threshold=200000.0/maxsrcrate=10.0/HA=1.0/mib=20000/mib=20000/vbrrate=124.41/t0v=120/a=1.15/b=1.05/qlt=0.8 / Date:11/20/95 180 160 140 120 100 ICR: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 / XRM: 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 128.00 / Graph: 6 80 60 40 20 Five Sources ACR for S1 Source Rate for S1 ACR for S2 ACR for S3 ACR for S4 ACR for S5 0 0 50 100 150 200 250 300 350 400 Time in milliseconds (c) Baseline UILI 2five-sources.r/option=8485/optionb=327/icr=1.0/time_int=200.0/sw_int=30/share=0.999/dist=1000/cif=4096/xdf=0.5/tof=2.0/rttq=1.0/tcr=10.0/trm=100000.0 tdf=0.125/headroom=1.0/t_threshold=200000.0/maxsrcrate=10.0/HA=1.0/mib=20000/mib=20000/vbrrate=124.41/t0v=120/a=1.15/b=1.05/qlt=0.8 / Date:11/20/95 180 160 140 120 100 80 60 40 20 Five Sources ACR for S1 Source Rate for S1 ACR for S2 ACR for S3 ACR for S4 ACR for S5 0 0 50 100 150 200 250 300 350 400 Time in milliseconds (d) Count-Based UILI Rates 2five-sources.r/option=1/optionb=199/icr=1.0/time_int=200.0/sw_int=30/share=0.999/dist=1000/cif=512/xdf=0.0/tof=2.0/rttq=1.0/tcr=10.0/trm=100000.0 tdf=0.125/headroom=1.0/t_threshold=200000.0/maxsrcrate=10.0/HA=1.0/mib=20000/mib=20000/vbrrate=124.41/t0v=120/a=1.15/b=1.05/qlt=0.8 / Date:12/01/95 180 160 140 120 100 80 60 40 20 ICR: 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 / XRM: 16.00 16.00 16.00 16.00 16.00 16.00 16.00 16.00 16.00 16.00 / Graph: 1 Five Sources ACR for S1 Source Rate for S1 ACR for S2 ACR for S3 ACR for S4 ACR for S5 0 0 50 100 150 200 250 300 350 400 Time in milliseconds (e) Time-Based UILI Figure 7.6: Five Source Con guration: Rates, Low ICR = 1.0 Mbps, Headroom = 1 Mbps, MaxSrcRate = 10 Mbps for 200 ms 243
after reaching the goal. The time-based UILI converges very slowly to the goal. Had the sources started using their ACR allocations earlier (than 200ms), it would have resulted in network overload. Bursty Sources Recall that bursty sources have active periods when they send data at the allocated rate and idle periods when they do not have data to send. From the point ofviewof the bursty application, the following two measures are of interest ( gure 7.7): Burst response time is the time taken to transmit the burst. E ective throughput is the average transmission rate of the burst. Figure 7.7: Burst Response Time vs E ective Throughput Figure 7.7 shows the arrival and departure of a burst at an end system. The top part of the gure shows a burst which takes a long time to be transmitted, and the 244
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after reach<strong>in</strong>g <strong>the</strong> goal. The time-based UILI converges very slowly to <strong>the</strong> goal. Had<br />
<strong>the</strong> sources started us<strong>in</strong>g <strong>the</strong>ir ACR allocations earlier (than 200ms), it would have<br />
resulted <strong>in</strong> network overload.<br />
Bursty Sources<br />
Recall that bursty sources have active periods when <strong>the</strong>y send data at <strong>the</strong> allocated<br />
rate and idle periods when <strong>the</strong>y do not have data to send. From <strong>the</strong> po<strong>in</strong>t ofviewof<br />
<strong>the</strong> bursty application, <strong>the</strong> follow<strong>in</strong>g two measures are of <strong>in</strong>terest ( gure 7.7):<br />
Burst response time is <strong>the</strong> time taken to transmit <strong>the</strong> burst.<br />
E ective throughput is <strong>the</strong> average transmission rate of <strong>the</strong> burst.<br />
Figure 7.7: Burst Response Time vs E ective Throughput<br />
Figure 7.7 shows <strong>the</strong> arrival and departure of a burst at an end system. The top<br />
part of <strong>the</strong> gure shows a burst which takes a long time to be transmitted, and <strong>the</strong><br />
244
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