kea dhcp client lease affinity

[sarcasticadmin]

Description

What is lease affinity?:

Suppose that a laptop goes into sleep mode after a period of user inactivity. While the laptop is in sleep mode, its DHCP client does not renew leases obtained from the server and these leases will eventually expire. When the laptop wakes up, it is often desirable for it to continue using its previous assigned IP addresses. To facilitate this, the server needs to correlate returning clients with their expired leases. When the client returns, the server first checks for those leases and reassigns them if they have not been assigned to another client. The ability of the server to reassign the same lease to a returning client is referred to as "lease affinity."

There are some interesting knobs we can tweak with regards to the things like client lease affinity: https://kea.readthedocs.io/en/kea-2.3.0/arm/lease-expiration.html#configuring-lease-affinity

Acceptance Criteria

• Is it worth setting up lease affinity for the attendee facing subnets (e.g. scale public fast/slow)?
• Propose the appropriate configuration changes to kea for client lease affinity

[owendelong]

1. I don't think it's particularly worth spending effort on.
2. We should make sure that we set authoritative true; in the KEA configuration files.

KEAs default behavior is to grant the requested lease unless it's been reissued. Most of the tweaks are to change lease expiration behavior, which we have pretty well tuned for the environment.

[sarcasticadmin]

@owendelong thanks for the feedback, I spun out #805 since it doesnt look like authoritative true;