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20011030: IDD setup at INM

>From: Pepo Juega <address@hidden>
>Organization: INSTITUTO NACIONAL DE METEOROLOGIA
>Keywords: 200110301335.f9UDZO126839 LDM topology

Pepo,

Hi Pepo.  Sorry you couldn't make it to the MUG meeting in Madison.

>I have a quasi-transcendental doubt about LDM topology.
>
>Let's suppose that my topology only contemplates two types of nodes.
>Feeder nodes just do that. They feed requester nodes. They should
>not feed each other though. Feedtype is unique (MCIDAS)
>(I just got two of these, meteosat & grid)

OK, this is the simplest type of setup.

>Requester nodes get info from feeders, but do not feed anybody else.

We call such nodes "leaf nodes", like leaves are the last thing at
the end of a branch of a tree.

>(I got plenty of these, lets use just two for the sample, alfa & beta)
>
>Now, to avoid having undesirable traffic across, I want to ensure
>that requester nodes do not bounce back any data to any other node.
>My topology should remain simple. Star-shaped, having only two sources
>feeding all requesters, but not feeding each other.
>
>           meteosat            grid
>             / \                / \
>            /   \              /   \
>          alfa  beta         alfa  beta 
>
>Now, meteosat should not get any data from grid, and viceversa.
>The fact is that grid is getting data from meteosat, and I suspect
>that the data arriving to grid is really coming from beta.

In order for any LDM machine to get data from any other LDM machine,
it has to request that data.  If no data is to be sent to your
feed nodes, then they should not have any 'request' lines in their
~ldm/etc/ldmd.conf files.

>How exactly should ldmd.conf be configured to meet my needs?

o configure 'meteosat' and 'grid' to "allow" requests from 'alpha' and
  'beta' 

o configure 'alpha' and 'beta' to make "request"s from
  'meteosat' and 'grid'.

>Does topology only depend on ldmd.conf?

Yes, the topology is solely dependent on configuration "request" and "allow"
lines in ldmd.conf.

>How about netcheck.conf?

No, this does not alter topology.

>When I run ldmadmin watch on a requester node (alfa) How do I
>distinguish which feeder node is sending me which product?

Good question.  I am not sure that you can tell exactly which machine
a particular product is coming from exactly.  I will have to check with
others here in the office to make sure that I am not missing something.

What you could do is run simultaneous notifyme commands on a specific
machine, one for the local machine and one for the machine suspected of
being a feeder (notifyme shows when a machine receives a product).  The
products that are listed in each notifyme invocation will have feed
type and time stamp information on them.  The feed pattern should then
indicate whether or not a particular product received on the local
machine was likely to have come from the remote machine.

>Once this is clear, we can move on to failover policies.

So, in your setup the only configuration lines in the ldmd.conf files
on data injection (feeder) machines will be "allow" lines, and the
only configuration lines in the leaf node machines will be "request"s.

Tom