I work for an Edu with multi-gigabit Internet connectivity and I get
questions from users saying "Why am I only getting 14Mb when I run this
speed test?" I have got to believe that the various Internet speed tests
(Speakeasy or dslreports) are rate limited to prevent someone from shutting
them down. I am able to get 300-400Mb running from a PC inside my network
to NDT servers located on Internet2, so that tells me my border and internal
network is healthy. Can someone on this list shed some light regarding
reliability and accuracy of these various speed tests especially for an Edu
with lots'o bandwidth? Thanks.
University of Texas Health Science Center - Houston
Adjust your TCP window size.
All the new OS's (IE Windows7) automatically adjust TCP window size.
Personally I've never found those website speed test to be that accurate
Agreed. Most of the sites are not accurate for large bandwidth locations. Speedtest.net is flash based, however I find that slightly more accurate up to about 50-100mbit range.
1: http://speakeasy.net/speedtest/issues.php (See the section on
inaccurate results over 20Mbps and that the test is meant for "residential
2: Speakeasy is a commerical ISP for both residential and business users.
That means it is in their best interest to encourage you to purchase their
services. I have no issues with Speakeasy and have used them personally
with great success in the past (great support but prices are a little high
for most residential users), but why would you test one provider's service
with a sales tool from another (competing) provider and expect accuracy?
Best analogy I ever saw to teach Phd's why the net was slow:
Take a vacuum cleaner with extensions. Make a set of end connectors
from smaller and smaller tubes (garden hose, and straw I think they
were duct taped to vacuum cleaner ends). Have the complainer try to
clean up a mess with each of the ends. Ask them why it took much
longer with the straw versus the regular end. For the dimwitted (eg
2-3 Phd's and various honors) elaborate that the vacuum cleaner is
like your computer.. for things local and on Internet2 you get a
regular hose. On going to DSlreports etc you are going at some point
through a straw. [Actually i think the tube had a straw duct taped at
the middle... and had things painted on it saying "What we control.
What we don't control. What they control. What they don't control" ]
At this point most people realized networking wasnt' the people to
1) The capacity that a campus has into I2 or NLR is different than the BW the campus purchases from their commercial provider(s).
2) The commercial BW test sites are not optimized for speed. They do not have unlimited capacity network connections. And, they have not tuned their network stack for HS operation: notably, their OS will impose memory limits on the socket / transmit-buffer pool; so even if a receiver advertises a big window, frequently the transmitter (speed test server) will never queue enough data to fill the pipe
3) Peering capacity is not what it should be into the networks used by some of the BW test sites.
A "series of tubes" anyone?
I'd also show them the rrd/MRTG graph at the perimeter. Be clear to them
about the units.
Never miss the chance to ask for more budget though. Tell them the ACL
filters clog and need changing regularly, just be inventive
Your observation is disturbingly bleak... do you have a recommendation?
...perhaps a site with good bandwidth and a cluster of iperf(1) boxes
There are better tools than a simple iperf server:
There are many perfsonar sites to choose from in I2/NLR land. Most gigapops and I2 networks run at least one.
The problem is the Faculty^Wusers are smart, but not experienced in networking, so they buy into the marketing and eye candy of the speed dials on the Speakeasy and assorted speed testing tool sites. They see low numbers and then are difficult to convince that the devil is in the details. (which is odd, because that's what they do as scientists.)
They also typically don't see the $$$$ spent on i2/nlr connections vs the $ spent on commodity internet connections.
The problem is the Faculty^Wusers are smart, but not experienced in networking, so they buy into the marketing and eye candy of the speed dials on the Speakeasy and assorted speed testing tool sites.
Not just them, we are constantly dealing with our new HS users who go to those sites then call us to complain that they are not getting the speed they are suppose to get...ugh! It's like clock work, a new circuit goes in and a few hours later we're getting the old "I went to Speakeasy...blah blah blah"!
There is also http://netalyzr.icsi.berkeley.edu/ which is an excellent
connectivity check, although your mileage may vary with higher-speed
bandwidth testing from it.