Bulk Throughput Measurements - ORNL
Bulk Throughput Measurements | Bulk Throughput Simulation | Windows vs. streams | Effect of load on RTT and loss | Bulk file transfer measurements
Measurements made on September 26 '01, from pharlap to sunbirdj (Gbps interface) are shown to the right. They indicate that the throughput maxima are around 90Mbps (the top 10% throughputs measured are above 87 Mbits/s. It is apparent that with a single stream at best one gets less than 50% of the maxima. The RTT from SLAC to ORNL was min/avg/max (std)=87.5/88.5/98.8 (3.21) msec. This corresponds to a window size of about 1100KBytes for a bottleneck of 100Mbits/s. Similar measurements from pharlap to sunbird (the 100Mbits/s interface) show that 10% of the results were over 82.9 Mbits/s and the maximum throughput measured was 85.5 Mbits/s. Thus the Gbit/s interface does not help much (e.g. maxima increased by < 10%). Tom Dunigan of ORNL writes: I think the last hop to sunbirdj is screwed up somehow. TCP slow-start from sunbirdj outbound is often very "extended". (We usually do our throughput testing to the AIX box stingray for that reason).
Pharlap gained access to ESnet at OC12 speeds (622Mbps) on November 6, '01. We therefore remeasured the throughput. The results are shown below. It can be seen that the maxima increased by about a factor of 2 to over 205Mbits/s.