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Chapter 2: Preparing for a WAN Deployment
All the parameters in the Mitigation Parameters for Rogue APs and Their Clients section apply to SmartPath APs that perform
automatic mitigation. In addition to the parameters explained above, there is one other:
Max number of mitigator APs per rogue AP: For automatic and semi-automatic mitigation, cluster members choose one
SmartPath AP to be the arbitrator AP, which is the one to which all the detector APs send reports. The arbitrator AP also deter-
mines which detector APs perform mitigation. When they start, they become mitigator APs. Set the number of mitigator APs that
the arbitrator AP can automatically assign to attack a rogue AP and its clients.
Semi-Automatic Mitigation
To configure SmartPath APs to mitigate rogue APs and their clients semi-automatically, expand the Optional Settings section and
select Semi-Automatic. This approach combines elements of both the manual and automatic approaches. Like manual mitigation,
you must periodically check for rogue APs and their clients on the Monitor > Access Points > Rogue APs page, choose a rogue AP
to mitigate, and start the mitigation process. Like automatic mitigation, the arbitrator AP automatically chooses which SmartPath
APs perform the attack. Because the arbitrator AP determines which SmartPath APs perform the mitigation, it does not matter
which entries on the Rogue APs page you select or how many you select. The arbitrator AP decides which SmartPath AP to assign
to do mitigation based on two factors: radio channels and RSSI values. If a SmartPath AP is already using the same channel as a
rogue AP, the arbitrator is likely to assign it as a mitigator AP so that it does not have to change channels to launch its attack. If
one SmartPath AP reports a stronger RSSI value for a rogue AP than another SmartPath AP, that also increases the likelihood of it
being selected as a mitigator because it is within closer attack range of the rogue and its clients.
2.3.6 Deploying with Confidence
Moving a large enterprise—or even a small one—to a WLAN for the very first time need not be daunting. If you have moderate
experience with LAN deployments of other types and you have taken time to get answers to the important questions that will
affect the network data load, you have every prerequisite for success. The bottom line is to remember to take stock of your
project before you begin to ward against unforeseen costs and performance bottlenecks. If you have considered the issues and
guidelines presented here, you are not far away from a successful WLAN deployment.
2.4 Basic Wi-Fi Concepts
The goal of this section is to provide some background on Wi-Fi propagation and how to lay out a wireless network. Although
radio frequency (RF) engineering is a rather complicated science, this section provides a simple overview on the basics of Wi-Fi
propagation and channel layout that you need to be able to install an enterprise WLAN.
The first thing to know is that Wi-Fi is forgiving. Wi-Fi tends to transmit a bit farther than you expect, and even in cases of
interference, it tends to just work. This can be both a blessing and a curse. It is a blessing because people will likely have access
to the network, and it is a curse because your overall performance might be suboptimal without obvious symptoms, like lack of
connectivity. Understanding the basics presented in this section will help ensure a high-performance layout.
The first concept to understand is signal strength and how it relates to throughput. Radio power is measured in decibels relative
to one milliwatt (dBm) where 0 dBm = 1 milliwatt, but decibels increase using a log10 math function. Rather than dusting off
your old math books and pulling out your calculator, look at the dBm-to-milliwatt converter that appears below. Often in Wi-Fi,
dBm and milliwatts (mW)—and microwatts (µW)—are used interchangeably. The following table converts between the two units
of measurement:
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Table 2-4. dBm-to-milliwatt conversions.
dBm-to-milliwatt
20 dBm = 100 mW
15 dBm = 32 mW
10 dBm = 10 mW
5 dBm = 3.2 mW
4 dBm = 2.5 mW
3 dBm = 2.0 mW
724-746-5500 | blackbox.com
dBm-to-milliwatt
2 dBm = 1.6 mW
1 dBm = 1.3 mW
0 dBm = 1.0 mW
-1 dBm = 794 µW
-5 dBm = 316 µW
-10 dBm = 100 µW
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