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Data latencies: could much of this be avoided? (fwd)


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Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
address@hidden             WWW: http://www.unidata.ucar.edu/
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---------- Forwarded message ----------
Date: Fri, 10 Dec 1999 12:45:13 -0600 (CST)
From: Gilbert Sebenste <address@hidden>
To: address@hidden
Subject: Data latencies: could much of this be avoided?

Hello all,

One of the things that was a hot topic in the UNIDATA Newsletter this fall
was the worry of the data feed latencies via the LDM.

While I know they are going to go a different route in the future sometime
to handle faster feeds, I'm wondering if there isn't something we can do
right now to stop a lot of the problem we're seeing.

Pete Pokrandt reminded me during the NOAAPORT circuit board fry to split
the NP feed into two when you request it from a site, channeling the data
into two pipelines instead of one. He does it, and he doesn't get
latencies (he's inside the same building, granted). That is, when you
request NOAAPORT data from a site, do this:

request IDS|DDPLUS noaaport.serverwhatever.atmos.edu
request HDS 10.30.28.22

I forgot all about this...and since I started doing it today, there have
been no problems. Granted, traffic is a tad lower today on our partial T3,
but not by very much. And, for the first time, we're not getting
latencies. We were only getting them in the afternoon, and not fatal;
usually around 30-45 minutes. But now, they've disappeared. That even with
a scrambled full NIDS feed coming through the pipeline on the SDUS5*
headers (downstream sites, I'll get rid of those shortly...sorry about
that). That means I know I'll be able to handle the data feed on October
1...and I want ALL the NIDS data from ALL the sites. So I'll be sucking in
anything with SDUS5* on it. 

Just a suggestion for those who are having trouble. Maybe the latencies
are mainly LDM created, as opposed to net-congestion.

And maybe I'm full of it. But I wonder how many of us are doing it, and
if everyone did it, would it help stop the latencies?

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Gilbert Sebenste                                                     ********
Internet: address@hidden    (My opinions only!)                     ******
Staff Meteorologist, Northern Illinois University                      ****
E-mail: address@hidden                                 ***
web: http://weather.admin.niu.edu                                      **
Work phone: 815-753-5492                                                *
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