(a) Implement a managed interface for each external telecommunication service;
(b) Establish a traffic flow policy for each managed interface;
(c) Protect the confidentiality and integrity of the information being transmitted across each interface;
(d) Document each exception to the traffic flow policy with a supporting mission or business need and duration of that need;
(e) Review exceptions to the traffic flow policy [Assignment: organization-defined frequency] and remove exceptions that are no longer supported by an explicit mission or business need;
(f) Prevent unauthorized exchange of control plane traffic with external networks;
(g) Publish information to enable remote networks to detect unauthorized control plane traffic from internal networks; and
(h) Filter unauthorized control plane traffic from external networks.