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Why NNMi shows a layer 2 connections connected to a VLAN

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Hello,

 

We are running NNMi 9.1x and we noticed that some layer 2 interfaces are connected to a VLAN.  That is incorrect according to the information we have.  We are trying to find out why NNMi shows that information. 

 

Any idea on why NNMi iis showing this?

 

Regards

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I disabled small network discovery for now and rely on CDP.  Seems to work for us.

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Go to your inventory workspace and open up your layer2 connections table, find the node and look at the source. I suspect you'll see its small subnets thats' the source.

Have a nice day 🙂

Andy Kemp
I've lasted longer in the technology industry than most certifications.
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Hello Andy,

You are right, they are almost all Small Subnets. What does that mean? Can you explain a little please?

I found this one however that is not Small Subnets:

ra-frcol1-02-01[Vl1],sd-frcol1-02-01[Fa0/23]


It is really Vl1 to Fa0/23

Thanks for your help.
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Fleet Admiral Fleet Admiral
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You'll need to look at the ip addresses assigned to each interface and see how your smal-subnets is configured. I run into this all the time with load balancers where the admins use the same address space for the cross-over between two chassis... even though they may be spread across the country, NNMI picks up the addresses and lumps them all together.

 

For your second instance whats the source of the L2 connection ? CDP ?

Have a nice day 🙂

Andy Kemp
I've lasted longer in the technology industry than most certifications.
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Hello Andy,

I got a lot of those small subnets connection from interface to VLAN. One exemple is a router connecting via the interface Gi0/0.7 to a switch Vl7.

If I understand properly, you are saying that this might be caused by an admin who copies a configuration over from one device to another that would cause this? The two devices are in the same site most of the time.

As for the second instance, one of the device does not have CDP enabled on all interfaces. I will ask the network admins to enable it on all interfaces.

Thanks for the help.
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Cadet 2nd Class Cadet 2nd Class
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I see the same sort of issues as well, it san be a bit of a pain sometimes, especially when you have vendor equipment that uses the same IP range on all units for things like failover links, but as far as I see it, using small-subnets connections does have its advantages and I'm extremely reluctant to turn it off. 🙂
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I disabled small network discovery for now and rely on CDP.  Seems to work for us.

View solution in original post

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