Is there a rule of thumb for the ratio of sensors to APs needed to accurately scan an enterprise's air space?
WIPS Sensor-to-AP Ratio?
5 Comments
AirTight does not recommend rule-of-thumb to determine # of sensors required as our RF Planner or Planning Service can be used to accurately determine the # of sensors required via pre-deployment RF planning. However, typically ratio of 1 sensor to 3-4 APs is deployed in an enterprise environment (i.e. typical office building). But again this is dependent on customer’s RF environment and how the APs are deployed (i.e. whether for bandwidth or coverage area).
Implementations vary based on deployment scenarios. Typical installations can have a WIPS sensor for every 3-5 APs. With Motorola integrated AP & sensors, the ratio can be dynamically changed based on changing requirements. Motorola AirDefense can leverage data from sensors as well as some WLAN APs to improve the accuracy of select applications such as location tracking.
Hi, Amit - Could you clarify what you mean by "leveraging data from APs to improve accuracy of certain applications?"
Does this mean your sensors can make use of use data stored in APs to better detect and prevent intrusions? Or what kind of data and "other applications" (aside from WIDS/WIPS) are we talking about here? What's the relevance of location?
Thanks in advance.
Joanie - Good questions.
The density of sensor deployments depends on what you want to do with WIPS. For example, if you only want to detect rogue devices, sensor density can be sparse. However, if you want to physically locate devices on a map ("location tracking"), you need much higher sensor densities so that 3 or more sensors can simultaneously pick up the received signal strength of a device that you can then triangulate on. Motorola AirDefense can obtain Receive Signal Strength Indicator (RSSI) information from multiple-vendor APs (such as Cisco APs) and can leverage the information to perform location tracking, without necessarily increasing sensor count.
Similarly, the recently announced Multi-vendor Infrastructure Management capabilities of AirDefense Enterprise allows our customers to not only detect misconfigurations, but also apply fixes in an automated fashion in a vendor-agnostic WLAN deployment.
http://mediacenter.motorola.com/content/detail.aspx?ReleaseID=12506&NewsAreaId=2
In essence, what we are trying to do is combine best of both worlds: the 24x7 sensing capabilities of dedicated WIPS radios, with enhanced functionality of being tightly integrated with infrastructure, without giving up security or increasing cost.
This will sometimes vary by an end-user's physical environment or overall goals, but a general rule of thumb is 1 sensor for every 5 to 6 access points.