known/unknown devices in cable networks
Here's the problem in a cable network. There is a need to maintain a list of known/unknown devices (cable modems owned by subscribers). This list can be 100k entries long or longer. Effectively, the only choice for handling this is the HR mechanism. There's no alternative in the Kea architecture for this problem. There will be many HR entries with actually nothing reserved, just MAC addresses of the cable modems (CMs).
Now, in the DOCSIS architecture, the CM itself it just transport and all the devices behind it (eMTAs, STBs, home routers, user laptops etc) will be identified by option 82 suboption 2 (remote-id). The remote-id option will have the value of MAC address of the CM. There will be more than one device using the same CM mac. Those devices are provided by the customers and have unknown MACs, so we can't preconfigure separate HRs for them.
The problems here are:
- it must be possible to identify the KNOWN/UNKNOWN status based on the 82.2 option contents.
- for the UNKNOWN devices, it must be possible to do something special with the packets: either drop them, which is a worse choice, or reassign them to a special subnet, which is a better choice (this could be a portal asking user to register his new device or perhaps tell him to pay his bills)
- (optional) there should be some easy way to update the HRs with information that user is temporarily bloked (most likely because he didn't pay his bills).
It seems very likely that to fulfull those use cases, we'll need a new, docsis specific hook.
Note: For those who have access, see Alberto's report section Host Reservations, subsection Reservations using Relay Agent Info.
Here's a struggle reported by another user: