Managed allocation and reserved ranges, auto-assign

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Hello,

I have a small question regarding networking, because the wording (and maybe my english level )makes it a bit difficult to really understand what’s happening.

In a subnet management page, I can choose whether this subnet uses a “managed allocation” or not, with the following tooltip :

  • Managed allocation: When enabled, MAAS allocates IP addresses from this subnet, excluding the reserved and dynamic ranges.

From this, I understand that if I have reserved (dynamic) range, e.g. like the screenshot below, nodes booting in MAAS would get IP addresses outside of this range (so, nothing between 10.0.0.101 and 10.0.0.213).

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But when I go read the “About managed subnets” section on this forum, I can read :

About managed subnets

When you enable management for a subnet, MAAS will:

  • Lease addresses for DHCP from a reserved dynamic IP range
  • Assign static addresses not included in a reserved IP range, typically via ‘Auto assign’ IP allocation mode for a node.

See the glossary for an explanation of the two kinds of reserved IP ranges MAAS uses.

From this, I understand the exact opposite : if the subnet is managed, the DHCP would lease addresses from the reserved dynamic IP ranges. Now, If I click on the glossary, I understand, again, exactly the opposite :

Glossary

  • Reserved range Mode operates differently depending on whether the subnet is managed or unmanaged:
    • Managed (subnet): MAAS will never assign IP addresses inside this range. You can use this range for anything, such as infrastructure systems, network hardware, external DHCP, or an OpenStack namespace.

So, what am I missing ? Is there a way to reword these (seemingly) conflicting explanations ?

Another related question : it seems my non provisioned nodes get an “auto-assigned” IP address, but I can manually edit their networking settings to change this IP to a DHCP assigned one… What is the difference between these two modes ?

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Thanks !

2

Hi @Reventlov,

Thank you for raising this, it’s good to have such feedbacks in order to improve MAAS!

I’ll try to clarify the situation:

  1. Dynamic range: This range will be used during the commissioning or the enlistment stage. In particular, MAAS DHCP server will pick up an IP from this range to PXE boot the machine.
    Then, after the machine has been commissioned/enlisted

    1. If you set the IP mode of the machine to DHCP: MAAS will pick up an IP within a dynamic range also for the other stages (like deployment and when the machine is powered on).
    2. If you set the IP mode to Auto-IP: MAAS will use an IP outside the dynamic ranges.
    3. If you set the IP mode to Static-IP: you can use any IP address you want outside the dynamic range (but you can use an IP within a reserved range.). If you try to use an IP within the dynamic range, you’ll get an error.

  2. Reserved range: MAAS will never assign IPs within this range in any case, unless you use the Static-IP mode and you assign the machine an IP within this range.

Does this clarify?

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Thanks for the message, I’m beginning to understand the network on MAAS. I think part of my misunderstanding stems from the use of “reserved”, in particular in the About managed subnets part, which is not about reserved ranges but dynamic ranges.

Thanks for the clarification !