Re: Topology Questions

On Wed, 15 Nov 2000, Jim Koermer wrote:

> During these episodes, my upstream site(s) is usually quite good with
> FOS latencies < 1 minute.

This would seem to point to either bad network connection to your upstream
host (or more likely since I believe you said this occurs with both your
primary and failover feed), limited bandwith at your site.

> I am thinking that the HDS feed is the culprit. Does anyone know if I
> turn my HDS request off whether this will affect my downstream feed's
> ability to get HDS? I think the answer is "yes".  

Yes, it would.  They wouldn't be getting any HDS.  Since you aren't
requesting it, you won't get it, and then there won't be any HDS in your
queue to feed them with.

But there are a couple of things you could try:

If you are requesting ".*" (i.e., everything) for HDS in the request line
of your HDS request in 'ldmd.conf'., you could employ a filter similar to
the one Unidata supplied when we transitioned from FOS to NOAAPORT back in
12/98.  The reason for this is that there is much more data on the
NOAAPORT HDS feed than there was on the old FOS.  This is the filter:

request HDS "(^[A-OQ-X])|(^[YZ].[^AHIJRU])" <upstream site>

But I would check with Unidata to see if this filter needs to be updated.

The other thing you could try would be to split your request lines,
isolating HDS from IDS|DDPLUS.  For example requesting IDS|DDPLUS|MCIDAS 
from your primary site and HDS from your failover.  That way, high
latencies on HDS would not necessarily result in high latencies on
IDS|DDPLUS (unless, of course, network congestion at your site is the real
problem, in which case you might see high latencies on both streams.


> Perhaps, I need to try splitting the IDD ingestion on two machines--one
> for HDS and the other for DDPLUS.

This is more complicated and could be a headache to maintain, so I would
try the other things first.  Also, if network congestion at your site was
the culprit, this won't improve matters much, if any.

One other thing you might want to try:  I can add an ALLOW line for
Plymouth to my ldmd.conf, so you can try feeding from Brockport on some of
these feeds and see if latencies are any better.

Tom
------------------------------------------------------------------------------
Tom McDermott                           Email: tmcderm@xxxxxxxxxxxxxxxxxxxxx
System Administrator                    Phone: (716) 395-5718
Earth Sciences Dept.                    Fax: (716) 395-2416
SUNY College at Brockport



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