[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[LDM #BWL-598225]: Question on LDM server behavior

This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Subject: [LDM #BWL-598225]: Question on LDM server behavior
  • Date: Fri, 02 Jun 2017 15:26:43 -0600
Jim,

> When an LDM server launches, does it initiate contact with upstream server to 
> establish connection
> For data flow over the established network connection?

Yes. For each REQUEST entry in the LDM configuration-file, a new, downstream
LDM process is created that initiates a TCP connection to (typically) port
388 at the upstream site.

> Are all future data feeds subscribed to delivered over that established 
> connection?

Yes. For each incoming TCP connection on port 388, the LDM server at the
upstream site creates a new, upstream LDM process that sends subscribed-to
data to the downstream LDM using the same TCP connection that the downstream
LDM initiated.

> Or are data feeds pushed from the upstream ldm server?

Not sure what you're asking. See the previous paragraph.

> I need to understand the data flows so I can determine if I need to put my 
> ldm server in a DMZ for
> External connectivity or if it can reside inside my campus network because it 
> initiates all of the connections
> For data feeds?

A downstream LDM must be able to create a TCP connection to port 388 at the
upstream site. You could run an LDM on your DMZ system and then have
LDM-s that are behind your corporate firewall request data from it.
Alternatively, if your corporate firewall allows internal systems to initiate
TCP connections to port 388 outside the firewall, then your LDM-s can all be
behind the firewall.

Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: BWL-598225
Department: Support LDM
Priority: Normal
Status: Closed
===================
NOTE: All email exchanges with Unidata User Support are recorded in the Unidata 
inquiry tracking system and then made publicly available through the web.  If 
you do not want to have your interactions made available in this way, you must 
let us know in each email you send to us.