Insider Security Tip Of The Month – Perimeter Protection

Perimeter security is an often-overlooked area of physical security design that can dramatically improve the effectiveness of your security. Small investment in external perimeters can provide significant protection to a building’s assets well before the other, more costly, measures are encountered. Good perimeter protection serves as a valuable line of defense for a physical security plan

The 5D’s of perimeter security are: Deter, Detect, Deny, Delay and Defend.


The deter perimeter is the farthest one from the location of the assets and is often a mix of physical infrastructure such as fences and lighting. Applying surveillance technology along the deter perimeter typically requires the use of overt, large enclosures, which make it obvious to all approaching the perimeter that they are under surveillance. Signs saying “no trespassing” or “area under surveillance” also aid in communicating a deterrent message to unauthorized persons.


The detection perimeter’s security objective is to monitor large areas of space to accurately detect possible unauthorized intrusion in time to respond appropriately. Surveillance camera technology, especially megapixel cameras, is very effective as an accurate detection tool. Important objectives are the timely notification to security personnel, and having the ability to digitally or optically zoom into the area where intrusion was detected.


The objective at the deny perimeter is to keep unauthorized persons out, while allowing authorized persons to enter. To perform this function the deny perimeter typically has access control technology or a manned security gate at the point of entry. The intention of surveillance at this point is to provide visual verification to the biometric or card access system.


The delay perimeter’s objective is to slow down an active intrusion enough to force the intruder to give up, or allow the security team to respond. Often, interior locking doors or other physical barriers are used to slow down the intrusion. Surveillance cameras can be used inside the delay perimeter to provide situational awareness and measure the effectiveness of the delay countermeasures.


The defend perimeter is typically a security personnel response that attempts to apprehend the intruder. Surveillance is used at this perimeter to record the apprehension and determine the effectiveness of the response. This final perimeter often includes the involvement of law enforcement and typically overlaps the other perimeters.