Re: [67ATTENDEES] Anyone get the 'broadband' connection in the IETF hotel

[Fred Baker <[e-mail]>]

So you may find this interesting. Last night, at 6:30, I started a  
ping study from my room to a computer back at "the ranch". You may  
look at the pictures at
	ftp://ftpeng.cisco.com/fred/sheraton/ping-study-11-7-rtt.htm

There are two charts, one of the ping RTT distribution, and one of  
the per-minute minimum, average, maximum, standard deviation, and  
percentage of loss. You flip between them (yes, this was done using  
Excel) by clicking on "chart1" and "chart2". The second is displayed  
on a log-linear chart, because the upper bound value is a 35 second  
RTT on a ping that happened a bit after 11:00 last nightand it would  
be really nice to be able to see the normal samples, which are in the  
60-500ms range. The delay distribution chart is interesting in this  
way: the 90% confidence delay is shown in the chart; the last 10% has  
samples, as I said, all the way from 750 ms to 35 seconds. But  
instead of the typical Poisson distribution in which 90% of cases are  
within zero and twice the mean, there is a big bump around the mean  
and a really long and pronounced tail in which there is a very high  
probability that delay on a packet is many times the mean RTT. I  
would guess that your average TCP is probably unnecessarily  
retransmitting a significant percentage of its transmissions simply  
because of wildly varying delay.

Basically, last night, there was a significant delay bump from 10:00  
PM to 1:30 AM and another one from about 6:00 AM to 8:00 AM.  
Surprise. 10:00 is about when we got back from the social, dinner, or  
whatever else we did last night, and 6:00-8:00 is when we are all in  
our rooms and haven't yet materialized downstairs for coffee.

Something about having 1000 internet geeks walk into a hotel that is  
designed for executive travelers and wonder what's happening back  
home :-)

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