Question about 2.11 beta

[candlerb]

Parent Interface Assignments (#1519)

Virtual interfaces can now be assigned to a "parent" physical interface by setting the parent field on the interface object. This is helpful for associating subinterfaces with their physical counterpart. For example, you might assign virtual interfaces Gi0/0.100 and Gi0/0.200 as children of the physical interface Gi0/0.

Just checking: does the parent have to be a physical interface?

Example 1: Virtual machine with eth0 and eth0.100. I would like to configure eth0.100 to have eth0 as its parent.
Example 2: Device has a LAG, and a virtual interface vlan256. I would like to configure vlan256 to have LAG 1 as its parent

[candlerb]

I can answer this now from beta.netbox.dev, and the answer is that parent interfaces can only be physical.

I can see why it might be problematic to allow virtual interfaces as parent (particularly avoiding cycles), but here's an example where I'd find it useful.

Consider pfSense as a "firewall-on-a-stick". If I run it on a physical device, where the external interface is "ix0", this feature will let me associate the "WAN" and "LAN" interfaces with ix0. (Today, I just create WAN and LAN with no explicit association).

However if I run pfSense as a VM, where the external interface is "vmnet0", and also create "WAN" and "LAN", I won't be able to associate them with the external interface.

[jeremystretch]

and the answer is that parent interfaces can only be physical.

You can designate virtual parent interfaces for virtual interfaces. Currently we only support device interfaces though; I don't think an argument was ever made for VM interface parents.

[candlerb]

You can designate virtual parent interfaces for virtual interfaces.

That doesn't seem to be true. Example at https://beta.netbox.dev/dcim/devices/98/

I have created virtual interfaces vlan123 and vlan123456. I have set a physical interface as the parent of vlan123, but vlan123456 doesn't allow me to set a virtual interface as its parent: vlan123 is not available in the drop-down list.

[tyler-8]

Parent interfaces on VMs would be useful for most of the same reasons they were introduced for devices. The CSR1000v, for example, can have sub-interfaces (GigabitEthernet1.100) just like a physical Cisco router. That sub-interface is treated as a "child" interface no differently.

[jeremystretch]

@candlerb I'm not sure what's going on there, and the demo data has been cleared out. However, I was able to create a virtual irb interface and assign to it three virtual child interfaces without issue:

[candlerb]

Hmm, weird, but it's easy to reproduce: here's the exact sequence of steps:

• Devices > Add
  • Role: Access switch
  • Manufacturer: Cisco
  • Device type: C9200-48P
  • Site: Butler Communications
• Add Interface (blue button at bottom)
  • Name: vlan123
  • Create and add more
  • Name: vlan123456
  • Create
• Change to "100 per page" to see them
• Click edit (pencil) next to vlan123
  • Select parent interface GigabitEthernet1/0/1
  • Update
• Click edit (pencil) next to vlan123456
  • Scroll through parent interface list
  • No vlan interfaces are visible as parent

Until the instance is wiped, this is visible at https://beta.netbox.dev/dcim/interfaces/1166/edit/?return_url=/dcim/devices/98/interfaces/

[candlerb]

Incidentally, the name prefix "vlan" isn't significant. I created virtual interfaces "asdf" and "zxcv" as well, and if I edit zxcv (say), then none of the other virtual interfaces are available to select as parent.

[candlerb]

This is really weird, it may be a caching issue. I came back, added interface "irb", Create and add more, and then "irb.100" - and then the full set of virtual interfaces was available to select from, including asdf / zxcv / vlan123 / vlan123456.

But then when I go back to vlan123456, and try to select a parent, it's still not showing any virtual interfaces as parent options.

[candlerb]

Actually, if I go back to irb.100, and try to change its parent interface, it's not showing any of the virtual interfaces as options any more.

OK, so what it appears to be is:

• Creating a new virtual interface lets you select a virtual parent: https://beta.netbox.dev/dcim/interfaces/add/?device=98&return_url=/dcim/devices/98/interfaces/
• Editing a virtual interface doesn't let you select a virtual parent: https://beta.netbox.dev/dcim/interfaces/1166/edit/?return_url=/dcim/devices/98/interfaces/

[jeremystretch]

Ah, I got it. We use two different forms for interfaces: InterfaceForm and InterfaceCreateForm. The former was filtering by kind but the later wasn't. When I tried to replicate it earlier I was assigning the parent during creation, so I didn't hit the bug. 🙂

Anyway, it's an easy fix thankfully. Thanks for tracking this down!

[jeremystretch]

Fixed this under #6106 FYI