Sprint Service Problems

Hank Nussbacher HANK at taunivm.tau.ac.il
Thu Dec 21 10:34:05 UTC 1995

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
>For months now, I've been asking them why our ping times look like:
>Sending 100, 32-byte ICMP Echos to, timeout is 1
>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.


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