The network IDS is not configured or implemented such that it can monitor the traffic to/from the required VVoIP firewall/EBC (function) as well as the traffic to/from the data firewall (function).

The purpose of the Internal Network IDS is to provide a backup for the enclave firewall(s) in the event they are compromised or mis-configured such that traffic which is normally blocked ends up being passed as well as to detect other malicious activity entering (or leaving) the enclave. As such the NIDS must be implemented in such a manner that it monitors all traffic flowing through the data and VVoIP firewalls. Minimally, it will detect improper data protocol traffic coming through the VVoIP firewall. While the NIDS will not be able to inspect the VVoIP signaling and bearer packet payload due to its encryption, it could detect anomalous behavior in the flow of these packets.

Additionally, per the NI STIG, the NIDS is required to be a separate device from the firewall for reliability reasons. If the common firewall/IDS platform is compromised, both the firewall and IDS is vulnerable.