ZyXEL Communications NXC5200 User Manual page 405

In the example above, a corporate network's security is compromised by a rogue
AP (RG) set up by an employee at his workstation in order to allow him to connect
his notebook computer wirelessly (A). The company's legitimate wireless network
(the dashed ellipse B) is well-secured, but the rogue AP uses inferior security that
is easily broken by an attacker (X) running readily available encryption-cracking
software. In this example, the attacker now has access to the company network,
including sensitive data stored on the file server (C).
Friendly APs
If you have more than one AP in your wireless network, you should also configure
a list of "friendly" APs. Friendly APs are other wireless access points that are
detected in your network, as well as any others that you know are not a threat
(those from recognized networks, for example). It is recommended that you
export (save) your list of friendly APs often, especially if you have a network with
a large number of access points.
NXC5200 User's Guide
Chapter 26 MON Profile
405