Packetshaper and LDM/IDD data flows

Hello LDM Users and IDD Participants,

Recently a few of our sites experienced data reception that was severely
throttled or stopped for no apparent reason. Symptoms were inconsistent
and somewhat sporadic and included: 

     extremely low throughput 
     latency problems 
     RPC time outs 
     "can't contact portmapper" messages 
     "no route to host" messages 
     ldmping failure, usually due to RPC time out 

In some cases a subset of products got through, but in other cases
nothing got through. 

It was finally determined that these sites had installed Packetshaper, a
product developed by Packeteer to analyze and "shape" traffic. It is
often used to limit traffic from low priority applications. Packetshaper
is a box that generally sits between a router and switch. Thus, there's
no way to tell whether it's running except to ask your network
administrator. 
This note is let our community be aware of the possibility that
Packetshaper may be affecting the flow of data into or out of their
sites.  

Also, we've been in contact with technical support at Packeteer in order
to help sites configure Packetshaper to allow IDD traffic to flow as
freely as possible.  For more information please see
http://www.unidata.ucar.edu/packages/ldm/packetshaper/packetshaper.html.

Anne
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Anne Wilson                     UCAR Unidata Program            
anne@xxxxxxxxxxxxxxxx                  P.O. Box 3000
                                  Boulder, CO  80307
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Unidata WWW server       http://www.unidata.ucar.edu/
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