Required roles: broadband-r

Optional roles: pricing-r

Returns the available subnets for the given circuit. Split up in available for primary and routed, ipv4 and ipv6.

routing_type says what the subnet would be issued as, which decides how it is priced: a fixed connection
terminates on a single IPv4 address free of charge, so with primary the /32 is quoted at no cost. It defaults
to routed, under which every address is charged for.