Preventing from assign fixed address based on class

[Paweł Warowny]

Hello

I work in docsis environment and hosts behind docsis modems and also
modems receive
IP addresses from the same dhcp server.
So I have plenty of host statements for modems and hosts like this:

host host1
{
       hardware ethernet 11:11:11:11:11:11;
       fixed-address 192.168.10.1;
}

host modem1
{
       hardware ethernet 22:22:22:22:22:22;
       fixed-address 10.1.10.1;
}

I can catch only modems easily this way:
class "cablemodem" {
        match if substring(option vendor-class-identifier,0,6) = "docsis";
}

The problem is, that if some customer assigns for his host some other
customer's  modem MAC address - he will get this address assigned for
his host.
Is there a way to prevent such behaviour?

I thought about:
allow members of "cablemodem";
statement inside host declaration, but it looks, like this is only
valid inside pool declaration.

Is there any other way to achieve it?

Best regards.