ISC DHCP spawning classes
ISC DHCP has spawning classes:
Many cable modem head-end systems can be configured to add a Relay Agent Information option to DHCP packets when relaying them to the DHCP server. These systems typically add a circuit ID or remote ID option that uniquely identifies the customer site. To take advantage of this, you can write a class declaration as follows: class "customer" { spawn with option agent.circuit-id; lease limit 4; } Now whenever a request comes in from a customer site, the circuit ID option will be checked against the class's hash table. If a subclass is found that matches the circuit ID, the client will be classified in that subclass and treated accordingly. If no subclass is found match- ing the circuit ID, a new one will be created and logged in the dhcpd.leases file, and the client will be classified in this new class. Once the client has been classified, it will be treated according to the rules of the class, including, in this case, being subject to the per-site limit of four leases. The use of the subclass spawning mechanism is not restricted to relay agent options - this particular example is given only because it is a fairly straightforward one.
The important statement is the manual is:
The reason that spawning classes were created was to make it possible to create lease-limited classes on the fly.
So they are very bound to the lease limitation feature. As Kea does not support it in fact the whole concept of spawning classes is useless for Kea...