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20051101: IDD latencies (cont.)



>From: "Patrick L. Francis" <address@hidden>
>Organization: BGSU
>Keywords: 200510312116.j9VLGv7s008531 IDD

Patrick,

re: I recommend you contact your campus computing/networking group to
report the degraded service.

>already have..

Very good.

>all of my servers are wide open and not capped...
>
>traceroute from me to idd = good
>address@hidden /usr/sbin/traceroute idd.unidata.ucar.edu
>traceroute to idd.unidata.ucar.edu (128.117.140.3), 30 hops max, 38 byte packe
> ts
> 1  router-112 (129.1.112.254)  0.375 ms  0.275 ms  0.240 ms
> 2  10.9.2.1 (10.9.2.1)  0.306 ms  0.340 ms  0.242 ms
> 3  10.9.10.12 (10.9.10.12)  0.377 ms  0.305 ms  0.268 ms
> 4  129.1.8.190 (129.1.8.190)  0.423 ms  0.418 ms  0.406 ms
> 5  gw-bgsu (129.1.8.253)  2.007 ms  2.791 ms  1.785 ms
> 6  toldb-r0-ge7-2s462.core.oar.net (199.18.159.17)  4.912 ms  5.221 ms  5.502 
> ms
> 7  clmbn-r1-po0-0.core.oar.net (199.18.145.17)  6.575 ms  7.098 ms  5.340 ms
> 8  clmbn-r0-po3-0.core.oar.net (199.18.145.1)  5.456 ms  5.861 ms  4.949 ms
> 9  clmbq-r2-po1-0.bb.oar.net (199.18.145.38)  5.277 ms  4.992 ms  5.376 ms
>10  abilene-IPLSng.ohio-gigapop.oar.net (192.88.192.134)  10.117 ms  9.849 ms  
>9.849 ms
>11  kscyng-iplsng.abilene.ucaid.edu (198.32.8.81)  28.877 ms  21.487 ms  19.03 
>4 ms
>12  dnvrng-kscyng.abilene.ucaid.edu (198.32.8.13)  29.700 ms  38.200 ms  29.82 
>0 ms
>13  192.43.217.129 (192.43.217.129)  30.180 ms  29.717 ms  30.094 ms
>14  gin.ucar.edu (128.116.254.240)  31.557 ms  31.274 ms  31.071 ms
>15  flrb.ucar.edu (128.117.243.83)  31.910 ms  30.957 ms  32.137 ms
>16  idd.unidata.ucar.edu (128.117.140.3)  30.817 ms  31.574 ms  30.828 ms
>address@hidden

'traceroute' listings are not a good measure of throughput you will get
using LDM/IDD/FTP/SCP/etc.  'traceroute' sends small packets and times
their round trip; realworld applications send large volumes of data
through the network.  Packet shaping software run by many university IT
departments is typically configured to limit the overall volume of a
stream, so if implemented so that it is controlling data flow on port
388 (LDM), you will see latencies climb.  A lot of times when there are
router problems, the effects are seen to be a direct function of
traffic volume.

>but both times after i mention it to address@hidden the peak drops without
>any changes on my end...

I imagine that the problem is not on your departmental machines, but,
rather, in the university network or in its connection to the Internet.

>http://www.unidata.ucar.edu/cgi-bin/rtstats/iddstats_nc?NIMAGE+unidata3.bgsu.e
> du

Yes, but compare this to other machines receiving the same data
from some of the same servers:

http://www.unidata.ucar.edu/cgi-bin/rtstats/rtstats_feedtree?NIMAGE

>perhaps the gremlins from Halloween are just a little overzealous this year.

:-)

Cheers,

Tom
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