SLAC to UFL
The measurements were made between pharlap.slac.stanford.edu and
iperf1.nslabs.ufl.edu at the University of Florida in Gainesville, Florida.
Pharlap is a Sun E4500 with
6*336MHz cpus and maximum buffer size of 8Mbytes running
Solaris 5.8. Iperf1 is an 800MHz P3 running Linux 2.4, with
4 MByte buffers and
a GE interface to the campus network. On 9/19/01 the campus link to
Internet 2 was at OC3.
The pipechar from SLAC to the University of Florida
indicates that, as expected, the route is via Internet 2 with some OC3 links.
Measurements made on September 19 '01, are shown to the right. They indicate that
the throughput maxima are around 100 Mbits/s.
It is apparent that with a single stream one can get 80% of the
optimum throughput with windows of 512KBytes. The RTT from SLAC to UFL
is min/avg/max (std)=65.1/66/220 (3.9) msec. This corresponds to
a window size of about 650KBytes.
Bbcp throughput from SLAC to UFL
We used the
progress reporting feature to report the incremental and
cumulative throughputs from SLAC to UFL with a window size of 512KBytes and 8 streams.
To save having to create and save large files the data source was /dev/zero and
the data was written to /dev/null.
It is seen to the right that the cumulative throughput (the magenta line)
creeps up to just under
80KBytes/s in about 100 seconds(~ 60Mbits/s), and then again increases
to about 87KBytes/s. If one accumulates the throughput in the intervals 16-
109 seconds (light blue line) and beyond 119 seconds (green line)
separately then two distinct cumulative throughputs of about 80 KBytes/s
(16-109s) and 100KBytes/s (> 119s) are observed. This may be caused by
external (to the current transfer) activities, such as changes in the
loading on the
computers at either end or changes in the cross-traffic on the bottleneck link between
SLAC and UFL. It also appears that the incremental throughput (aside from possible
external activity effects) reaches a maximum after about 15 seconds.
Bbcp throughput from UFL to SLAC
We installed the bbcp executable on iperf1 (unfortunately iperf1 did not have AFS to
access the bbcp program from the slac.stanford.edu cell). We also set up ssh keys so
we could run bbcp automatically without requiring a password for the remote bbcp peer each
time it executed.
We made measurements transferring a 500MByte file with different window
sizes and numbers of streams.
Measurement durations varied from 63 to 2119 seconds. The measurements shown below
indicate that the maxima (i.e. the top 10% throughputs) of the bbcp
throughputs are about 67Mbits/s compared to about 95Mbits/s for iperf. It is also apparent
that the optimum window size is 256KBytes or greater.
Sample Bulk Throughput Measurements
Cal Tech |
Colorado | IN2P3 |
INFN |Daresbury |
Stanford to Daresbury |
ANL |BNL |
LBL |SLAC To Stanford's Campus|
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Summary of Bulk Throughput Measurements
Created September 19, 2001, last update September 19, 2001.
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