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Network Sonar Discovery - Class A networks

feltonlewis over 4 years ago

According to SW they recommend the following when using subnets for for the NSD.

Subnets

Use this option to scan every IP address in a subnet. SolarWinds recommends scanning at most a /23 subnet (512 addresses max).

Scanning a subnet returns everything that responds to ping, so we recommend only scanning subnets where the majority of devices are objects you want to monitor.

How have you handled class A networks with /16 addresses? Using a /23 will generate over 32K subnets.

So do you use seed routers, AD, or another method when dealing with large addresses?

TIA.

0 mesverrum over 4 years ago

How many actual objects are you expecting to find in that sea of ip addresses? I don't believe in having Orion just wandering through my networks guessing at stuff to try and connect with.
Do you have actual lists of ips in use?
Even using a seed router can be a pretty sloppy way to get lists of subnets. Router won't differentiate between dhcp workstation subnets, that I generally don't want to try to include, versus the network mgmt subnets that have the gear I'm actually looking for.
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0 feltonlewis over 4 years ago in reply to mesverrum

I have a list of subnets that I have been scanning but the list I was provided have some /16 networks which are too large to scan.
A seed router will not help unles there is a way to distinguish the end device.

The question still remains, how to handle large /16 subnets?
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0 mesverrum over 4 years ago in reply to feltonlewis

all you can do is break them up. If you can't get a more narrowly scoped list of subnets then if it was me I would just write a script to do build discoveries in batches. Maybe something like break the /16 into many /22's and after that completes have it build a new discovery with the next /22. I expect it will take a long time to work through the list. Might be faster if you start by using a tool like nmap to at least do the initial ping sweep and build your hit list off the data that comes from nmap?
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