[PLUG] testing internet link speeds, playing with ping

[Keith Lofstrom]

Providers are accused of throttling - which could be on
the customer or the backbone side of the head end switch.
What are good tools for measuring that?

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I ran (as root) the command:

root# ping -f -q -l 100 -s 1250 -c 100000 

That sends out 100,000 10 kilobit packets (1 gigabyte)
and times the two-way conversation.   On my internal
gigabit network, times range from 1.7 seconds ( 590 mbps )
to 17.6 seconds ( 57 mbps ), correlating with the speed
of the transmitting machine.  

On my 15/5 mbps Frontier FIOS link, I can find the subnet
I am on, and look for the switch.  "route -n" on my
firewall tells me I am on the 50.53.88.00 subnet, so I
ping 50.53.88.01 .  From the firewall and the internal
machines, I get gigabit times ranging from 206 to 247
seconds, 4.9 to 4.1 mbps, about as expected since it
ping bandwidth is limited by the 5 mbps uplink speed.

Testing the download link speed of my connection from
Frontier's head end?  Not sure how to do that.  I can
ping from my Fremont, California offsite server.  At
430 pm Wednesday afternoon, I got 91 seconds / gbit to
the 50.53.88.01 head end and 193 seconds / gbit to my
50.53.92.xx firewall (still 5 mbps).  Both are slower
than I would expect, but the head end response rate
seems far slower than I would expect - that head end
is feeding hundreds of customers.

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BTW, deconstructing that ping command:
  -q : means quiet, no terminal output until ping is done
  -f : means flood ping - send them out as fast as 
       possible until ...
  -l 100 : ping stops sending packets if more than 100
           packets haven't returned yet
  -s 1250 : 1250 byte, 10 kilobit packets.  The returning
          acknowledgement packets are much smaller.
  -c 100000 : do this 100 thousand times - 1 gigabit total.

I can't use more than -l 150 on my machines (buffer size
limits), and for long distance links, many packets can be
on the fiber before the first returns.

Keith

-- 
Keith Lofstrom          keithl at keithl.com
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