Re: [opennms-discuss] Is Opennms IP only?

[Jeff G. <je...@op...>]

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On Mar 14, 2008, at 4:33 PM, Matt Stevens wrote:
> We have a unique identifier that identifies a node - it's just not  
> an IP
> address. We happen to use DNS to map this to a host, so for instance
> afd1ef23-be4c-38c7ff.vpn.acme.com maps to an IP address. The IP  
> address
> happens to change occasionally, but the host ID never does - nor do  
> any
> of it's interfaces or services (other than the VPN connection).

This describes exactly the sort of situation for which we built the  
model importer.  In fact, if you replaced the terms "DNS" with "a  
provisioning system" and "VPN connection" with "site", you'd be  
extremely close to the very customer requirement that was the impetus  
for developing the model importer.  The customer for whom we built it  
had a different reason for needing it (they set up entire site  
networks with a very short lifespan as part of their business), but  
the base problem ("nodes move around") is the same.

> If there is a way to monitor a device based on some identifier other
> than IP, I could use that mechanism.

There's not a way today to have OpenNMS monitor a device using some  
token that is not an IP address, but the importer allows a node's IP  
address(es) to be changed without OpenNMS really knowing or caring  
that it happened.

> I definitely didn't mean to get anyone's hackles up, I was just
> surprised that this was a "harder than it looks problem" - given how
> flexible and configurable OpenNMS seems to generally be.

A very large part of the reason why it's so flexible and configurable  
is that OpenNMS strives to avoid ambiguity, especially at the lowest  
layers.  If you want to build a house that is enormously adaptable and  
reconfigurable, you do that by making the foundation go down to the  
bedrock and using pillars instead of load-bearing walls to bear the  
weight of the roof.  Then you can move around all the walls to suit  
your needs, because they're all non-structural partitions.  To have  
support for DNS names in place of IP addresses would be akin to making  
the foundation shallow and reconfigurable and every wall load-bearing  
- -- it can be done, but the foundation will not be as solid, and you  
might not be able to build a house with this design at all in a  
location that has sandy soil.  OpenNMS has a deep foundation and a few  
thick pillars holding up the roof.  The price you pay for the ability  
to move the walls around is that you'll sometimes have a pillar in an  
inconvenient location.  Hang some fine art on the pillar if its  
presence bothers you ;)

- -jeff
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