User's Guide

• Connection Termination—To terminate a devices connection to your network, the device must be in
range of a sensor sending termination signals.
• Policy Enforcement—To ensure adherence to policies or to detect attacks against managed devices,
sensors must be able to receive a representative sampling of trac sent by all devices they are
monitoring.
• Rogue Detection—iEven sporadic emanations from wireless clients and s can reveal the presence of
rogues. You need to place sensors where transmissions from rogue devices can be detected as soon
as they enter the scanning area.
Assets to be Protected
• Wireless-capable devices that contain sensitive data must be protected.
• Wired networks protecting the wire from wireless breach. This approach is key to making wireless
monitoring deployment decisions in very large installations, such as military bases, airports, power
plants, campuses, etc.
• A common perception is that wireless devices must be detected and monitored throughout a given
property. This becomes impractical in many cases. A more practical approach is one that protects
the wired network while using more sane decisions for monitoring.
Sensor Quantity and Placement
Application choice will significantly impact the sensor density and sensor placement. For example,
rogue detection in a no wireless zone needs fewer sensors as even sporadic emanations from a wireless
device, at the lowest data rate and longest range, can reveal the presence of a rogue. As the
applications become more complex, they may require a representative sample of frames or meet
certain minimum signal level thresholds, increasing the sensor density requirement.
Using these factors in baseline decisions with regard to sensor placement, the following coverage area
guidelines may be applied to establish an eective deployment.
Application RSSI
Rogue Detection > -90dBm
Policy Enforcement > -80dBm
Mitigation (Termination) > -70dBm
Location Tracking Every device has to be seen by three or more sensors and/or
infrastructure APs on the same floor plan.
Sensors that may be exposed to harsh environments can be placed in accessory enclosures (NEMA-4)
that protect the sensor and provide code, regulatory compliance, or both.
Power and Data Cabling
Sensors are often placed in areas that take advantage of pre-existing power and data cabling. These
areas include wiring closets and other areas where IDFs may be located. Where these locations are
somewhat shielded from the wireless environment, the sensor may be extended to just outside of these
spaces using standard power cords and pre-terminated data cables, obviating the need for additional,
costly fixed runs. Choosing facilities that come as close to centrally locating the sensors in the intended
monitoring space should be done when practical. In instances where wiring closets, IDFs, or both are
Security
Device Placement Considerations
Extreme AirDefense User Guide for version 10.5. 847