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20030825: request for help from SJSU



Mike and IDD Users:

IDD data reception at SJSU recently and abruptly transitioned from
excellent to unacceptable.  The time series traces of IDS|DDPLUS
and HDS latencies on the SJSU IDD node, rossby.met.sjsu.edu, can
be seen in the following links:

IDS|DDPLUS:
http://www.unidata.ucar.edu/cgi-bin/rtstats/iddstats_nc?IDS|DDPLUS+rossby.met.sjsu.edu

HDS:
http://www.unidata.ucar.edu/cgi-bin/rtstats/iddstats_nc?HDS+rossby.met.sjsu.edu

For reference, Mike split his original WMO feed request into separate
IDS|DDPLUS and HDS requests sometime between 16Z and 17Z this morning.
The traces listed in the links above show that virtually all of the
latency that Mike is seeing is being cause by HDS product ingestion.
His IDS|DDPLUS latencies has fallen to near zero, while those for HDS
continued to be very high, climbing to over 8000 seconds even after the
split.

We believe that the latency time series listed above depict a "classic"
volume limitation on data flow.   We (Unidata Support) have seen this
kind of volume-limiting at several universities that implemented "packet
shaping" to control data volumes.

If the cause for Mike's poor HDS data ingestion turns out to be the same
as for others, the only thing that can be done is to contact the campus
networking folks to see if they are willing to allow port 388 traffic
to flow unimpeded.

>I'm trying to convince my campus network folks that we have a serious network 
>bandwidth/congestion problem. This problem does not seem to be related to
>total campus traffic. I have supplied them with several pieces of evidence,
>but I'm looking for more and that's where you can help.
>
>I occasionally download data from motherlode.ucar.edu as a backup to lost IDD 
>data.  Currently, when I download I'm getting speeds of around 35 Kbps, which
>is just horrible. However when I retrieve the file on my local network I get
>7500 Kbps. The difference is poor network performance going through all the 
>switches and firewalls between my network and UCAR. Could some of you (who
>have access) download some data from motherlode via ftp or http and tell me
>what kind of transfer speeds you get? This would be interesting info in is
>own right, but might also provide me with some more ammunition for my case
>with my network folks.
>
>Thanks for your help,
>-Mike
>--------------------------
>Mike Voss                                
>Department of Meteorology               
>San Jose State University                        
>One Washington Square                      
>San Jose, CA 95192-0104   
>             
>408.924.5204 voice
>408.924.5191 fax   

Tom
- --
+-----------------------------------------------------------------------------+
* Tom Yoksas                                             UCAR Unidata Program *
* (303) 497-8642 (last resort)                                  P.O. Box 3000 *
* address@hidden                                   Boulder, CO 80307 *
* Unidata WWW Service                             http://www.unidata.ucar.edu/*
+-----------------------------------------------------------------------------+

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