[TIGGE #BGR-338705]: A problem when perform LDM tests

Hi Yangxin,

re:
> We have contacted CSTNET people, they suggested us to test LDM using port 388 
> on
> two servers. First, test both servers in the same network; second, test with 
> a firewall
> between two servers. If there is no problem, we might move one of my test 
> server to
> CSTNET to perform some additional tests.

This is an excellent set of tests to run.

> In order to move the test evenironment easily, I use a laptop computer with 
> VMware
> Virtual Machine running a Redhat Linux on top of my Windows System, the other 
> server
> is a real machine, but I met a problem when testing. Both the LDM Server in 
> the real
> machine and the one in my virtual machine can successfully "ldmping" with 
> each other
> (in the same sub-network), but the downstream never receive data from the 
> upstream.
> So what is the most probable cause for this problem?

A likely cause of the problem is the clock being off on one or both of the test 
machines.
For instance, if the clock on the machine requesting data is in the future with 
respect to
the machine that will send the data, the request that will go from the 
requesting machine
will ask for data that is also in the future.  Please check the clocks on both 
machines
and set them if they are off.  For these simple tests it is not necessary to 
run 'ntpd'
continuously.  A simple invocation of 'ntpdate' specifying the same timeserver 
from both
machines will insure that their clocks are close enough to run the tests.

Note:

- 'ntpdate' and 'ntpd' can not run at the same time
- both 'ntpdate' and 'ntpd' need to be run as 'root'


> By the way, if some time later, we would test LDM using port 388 somewhere 
> out of CMA
> in the CSTNET with Unidata LDM Server, is there any LDM Server to which I can 
> perform
> the LDM test?

Yes.  We can setup one of our machines to allow your machine(s) for testing.  
Please
provide us with the fully qualified hostname of whatever machine you will use 
for
testing so we can setup the appropriate 'allow' line(s) on:

yakov.unidata.ucar.edu

> I mean, current LDM Server that exchange data with CMA is 
> "ultrazone.ucar.edu", but port
> 8080 is being used, can I test port 388 with this server?

Port 8080 is being used by virtue of 'balance' running.  The LDM on ultrazone 
is setup in
the standard fashion to use port 388.  I would recommend, however, that you use 
a different
machine for testing than ultrazone since it is more-or-less operational.


Cheers,

Tom
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Ticket Details
===================
Ticket ID: BGR-338705
Department: Support IDD TIGGE
Priority: Normal
Status: Closed