What Dependencies are Implicit?

[philip.mayo]

We just got SolarWinds NPM for our network.  Our network is full of WAN dependencies, so I am setting them up, but I need some clarification.  Before I create a bunch of unnecessary dependencies, I need to know what are already implicit?  What Nodes and Interfaces will automatically become Unreachable without an explicitly defined dependency?  It is a live network, so I do not have the freedom to experiment to derive my own answers.

If a node is set to Unreachable as the member of a Child group whose dependency has been triggered:

1. Do the interfaces of that same node also become Unreachable?
2. Do the dependencies for which that node is a Parent also trigger?
3. Do the dependencies for which any interfaces of that node happen to be Parents also trigger?

Thanks,

Phil.

[superfly]

The only implicit dependency is the interfaces. So when a node goes down, the interfaces are marked as unreachable and you'll only get a notification for the node going down. This is automatic. The rest of the dependencies you need to create.

If a node is a parent for other nodes and it goes down, the other nodes will be marked as unreachable (inc the interfaces) and you'll only get a notification for the parent.

I hope that answers your questions.

[philip.mayo]

superfly99 wrote:

If a node is a parent for other nodes and it goes down, the other nodes will be marked as unreachable (inc the interfaces) and you'll only get a notification for the parent.

You answered my first breakdown.  I need deeper clarification on the dependency hierarchy.

My dependency parents are not nodes, but normally groups of interfaces, or a single interface, the children of which are nodes.  I am asking if the child nodes' interfaces are included (which you answered I think), and any dependency for those interfaces from that secondary node also included.

Here is an example of one set of dependencies:

Parent A - group of interfaces (GRE tunnels) - all must go down (worst) for isolation

Child A - group of nodes dependent on those tunnels

Parent B - interface on a node from Child A group

Child B - another node not already included in Child A group

If all the interfaces in Parent A group go down, triggering the first dependency--I have your answer that the interfaces for Child A nodes would also become unreachable--does the node of Child B (and, I assume, its interfaces) also become unreachable?  Should I include the Child B node in the Child A group, or do the dependencies cascade correctly?

Would this cascade to a further dependency?

Thanks,

Phil.

[superfly · Accepted solution]

If Parent A goes down, then Child A would become unreachable. And Child B will also become unreachable as Parent B has become unreachable due to Parent A going down.

If Parent A goes down, then all the interfaces on Child A and Child B will also become unreachable. This dependency is automatic.

Hope that helps.