Subnet size limit for populating IP addresses

Hello folks,

The default subnet size limit that auto-populates the subnet with IP addresses, is a /20 (4096 IP addresses). I deal with numerous large subnet sizes just shy of this limit. Curious if there's any back-door methods to rig it for a larger size limit, perhaps a /19.

I'm fully expecting there's really no way to change this, but I wanted to ask anyways. Perhaps a feature request is in order.


  • When you say default subnet size is /20, what do you mean?  In your environment, are you operating with single network segment that is a /19 or /20?

    Have you tried adding an address range instead of using CIDR?


  • Hi Bryan,

    Here's some more info. When adding a subnet into IPAM, it'll auto-add IP addresses of the subnet to IPAM for any subnet size of /20 or smaller. See the screen caps below. If I wanted to add a /19 that is not subnetted, it would not populate automatically and the check-box is grayed out. Then afterwards these IP ranges have to manually added to these /19 subnets.

    Adding a /20:


    Adding a /19:


    Then to add the range manually:


  • Okay, I get where you're coming from as far as the range add.  Just to make sure I am still understanding, you are adding a /20 for the discovery of multiple subnets?  For instance, you have a bunch of /24 networks or something like that, that all fall into the /20 you are adding?  That is sort of looks like the case from the screenshot with the numbers to the right. 

    Either way, I was recently at a Federal Partner training with the SolarWinds staff, and I believe the /19 could cause a lot of issues for most standard issues as far as the back-end work required to process that address space.  I have not used IPAM in a while so I don't recall how long it takes to discover a standard /24, but with larger networks you have to consider the work that has to occur in the Orion DB, the the poller traffic, and the conversation attempts with the DHCP server, if configured.  This could very well be a feature request, but I don't think the software is robust enough to handle the queuing for a /19 or larger sized network discovery without slowing the entire platform to almost a complete halt.

    Perhaps edbarbieri​ could speak to this or tag someone that would know better than I.


  • Thanks Bryan, though I'm specifically focused on when we're adding /19 subnets that truly exist at a host level -- and are not subnetted out into smaller subnets.

  • In that case, I think your best bet would be submitting a feature request.  This is a service provider level request that should be configurable in the Orion platform back-end.  I wish you luck in your quest.

  • I'm kind of swamped, but I'll look at this later tonight and get back to you.