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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Sprint Service Problems
On Wed, 20 Dec 1995 01:11:30 -0700 (MST) you said:
>Time for me to jump on the bandwagon.
>
>We're a Sprint Customer. Right now we have a 256K fractional T1 line to
>the net. We're tied to Stockton-7. "Our End" of the line is in Helena
>Montana.
>
>For months now, I've been asking them why our ping times look like:
>Sending 100, 32-byte ICMP Echos to 144.228.47.21, timeout is 1
>seconds:
>!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
>Success rate is 100 percent (100/100), round-trip min/avg/max =
>100/104/204 ms
>
>Note the 100 ms. I have NEVER seen it below 100 ms EVER. No matter what
>the traffic, time of day, etc. Well, maybe I've seen it at 98 or 99 once
>or twice.
>
>In theory, a round trip time should be two times the single direction
>distance, which should be composed of the following two items:
>
>1) 256K maximum bitrate (amount of time to clock the bits out) -
> 32 bytes * 8 bit bytes = 256 bit times
> 256 bit times * (1/256,000) (one bit time) ~= 1 ms
>2) Speed of Light Limit (The Rest)
> In vacuum, light can travel 186 miles per millisecond.
> Not sure how much it differs in fibre, but I figure that
> even if you assume that its 150 miles per millisecond,
> you can travel roughly 7000 miles in the remaining time (59ish ms).
>
>So, that puts my link 7000 miles away. Now I'm curious as to how they
>have my line routed over 7000 miles. So I call up their INSC and ask who
>I can talk to about this. I end up opening a trouble ticket, and
>eventually the engineer I talk to say's that it is in the acceptable
>limits for the distance of circuit, which they tell me goes from Helena
>to Seattle and then to Stockton California in more or less of a straight
>line between the points. According to my calculation there's about 1200
>miles of fiber there. Still 5800 miles short.
>
>I backed off after reading some papers on ping times versus maxumum
>flow. That is until I had an outage last week caused by a Fiber Cut in
>Texas. Now I'm mad. I supposedly have a line from Helena to Seattle
>to California which somehow goes through Texas. After finally yelling loud
>enough about either this cut not being my problem or my line isn't routed
>where I was told it was, I finally got a manager or VP who was kind
>enough to tell me that my line is routed through Arizona, and Texas, and
>a couple of other places in what I call the "mideast", and then to the
>Dakotas, through montana to the spokane (eastern washington) area, and
>then back to Montana. Adding up the miles, I get about 4-5,000 miles.
>I can believe that, with some switch latency.
Here are some tests I have done at 256kb:
Line From-to Medium 8000 octet 1000 octet 32 octet
speed ping ping ping
in seconds in seconds in seconds
----- ------------- ---------- ---------- ---------- ----------
256kb Israel-Israel fiber .524 .068 .008
256kb Israel-Israel FR, CIR=0 .628 .144 .016
256kb Israel-USA satellite 1.096 .640 .572
256kb Israel-Europe fiber .576 .116 .052
For 32 octets and 100ms - that is twice the rate we get with
a fiber link from Tel-Aviv to Geneva - a few thousand miles.
Hank
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