TLA = Top Level Architecture TLA stack includes, at a minimum,
an Security Router and an Intrusion Detection System or Intrusion
Protection System. The IDS/IPS scans traffic for known signatures
of malicious traffic. In addition to these devices, a TLA stack may
include a DNS, a reverse web proxy, and a firewall. Each of these
devices provides a layer of security to the installation it is
protecting. -Ben M. aka The man