Ring topology parent/child relation Nagios

[Hugo van der Kooij]

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Mihai Tanasescu wrote:
| Mihai Tanasescu wrote:
|> | I have some problems defining the parent/child relationships to reflect
|> | changes and monitoring on the map.
|> |
|> | My topology is something like this:
|> |
|> | Nagios machine --- Router A ---- Router B
|> |
|> | Router B --- Router C --- Router D --- Router E ---Router F ---
Router B
|> | (ring closing itself)
|> |
|> | but on the Router B ring I can't define parent relationships in a
|> | circular way because nagios refuses to start when it detects this.
|>
|> The whole concept of a ring setup is that a single disaster can not
|> cause a network failure. For this setup I would only follow the ring
|> halfway.
|>
|> So you get 2 chains:
|>
|> Nagios --> A --> B --> C --> D
|> Nagios --> A --> B --> F --> E
|>
|> Make sure you monitor each neighbor on each ring router to make sure the
|> ring is working as expected.
|>
|> If you use dynamic routing you might want to monitor route changes
|> relevant for the proper operation of your ring setup.

| Thanks for the tip but I have one more question which refers to my
| current problem in fact. (I configured sms sending for down events).
|
| In case for example router B loses both its links to C and F (2
| fibercuts on the network), then I will be getting SMSes stating that
| C,D,F,E are down.
| B in fact will not be down as a system but will be unable to reach the
| others.
|
| How could I solve this and avoid sending misleading sms messages
| regarding down events?

This problem should not exist.

Because if you cut the ring in 1 place all nodes can still be reached.
So no router will go down. If you cut it in 2 places you loose part of
the ring and only get alerts for the nodes directly on the other side of
the cuts from your perspective.

If you alert on unreachable as well then you get all the alerts you
tried to get rid of by introducing the parent relation in the first
place. So don't use them.

You need an additional means of detecting your first cut in the ring as
all routers can still be reached at that time and you will never know
you had a problem unless you alert on the actual link conditions.

Now getting the link condition to Nagios is something you need to work
out. Due to the lack of details it will be hard to help you there at the
moment. But considere the links to be the vital services for the host.

Hugo.

- --
hvdkooij at vanderkooij.org               http://hugo.vanderkooij.org/
PGP/GPG? Use: http://hugo.vanderkooij.org/0x58F19981.asc

	A: Yes.
	>Q: Are you sure?
	>>A: Because it reverses the logical flow of conversation.
	>>>Q: Why is top posting frowned upon?

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