Cisco Cisco Aironet 3700i Access Point 백서

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Effectively, these capabilities mean that bring your own device (BYOD) also means “bring your own access point”
or “bring your own network” and therefore, “bring your own interferer.” Thus, the threat from a rogue becomes less

about security and more about consuming excessive air time, resulting in degraded performance. This can be

especially troublesome in high-density public venues but can also be problematic in enterprises.

So in addition to Cisco CleanAir (which mitigates and reports on non Wi-Fi interference) and RRM (which primarily

prevents self-induced neighboring access point interference through DCA and TPC for the entire WLAN), Cisco is

effectively merging aspects of both of these solutions in order to provide improved mitigation of Wi-Fi that is not

affiliated with the production WLAN.

Accounting for rogue Wi-Fi interference is accomplished by configuring a trigger threshold for ED-RRM. This is

effectively a severity indicator so that the affected access point that has ED-RRM is additionally triggered by Wi-Fi

interference.

Since rogue severity is now added to the ED-RRM metrics, this provides the capability of a faster channel change

than the typical DCA cycle. In other words, if a rogue is interfering with airspace, then instead of waiting until the

next DCA cycle to elapse, change the channel as quickly as possible. This is the same behavior as for mitigating

non-Wi-Fi interferers with Cisco CleanAir technology.

Since Wi-Fi interference is becoming more prevalent, rogue access points that are serving traffic to clients (that is,

mobile access points) or client devices creating their own networks in real time means that air quality will be

affected. Wi-Fi needs to be prevented from becoming a problem by reacting to the presence of client devices

acting as independent, unaffiliated networks.

Air Time Fairness (ATF) - Basic Concepts and Goals

The easiest way to envision ATF is the ability to provide both monitoring and managing the amount of time on the

air for a per-client type, per-SSID, or per-other basis. The effect is to control the amount of traffic a group of clients

or SSID is sending into the WLAN and receiving from the WLAN at any one time.

In other words, the primary goal for ATF is to help avoid any one type of client or SSID from occupying an unfair

amount of Wi-Fi air time on a particular channel (for instance, on a given access point or radio). In accomplishing

this, ATF provides a customer the ability to define what fairness means within their environment with regard to the

amount of on-air time and the amount of the traffic that can be sent in any one time period. Thus policed or rate

limited leads to a notion of entitlement.

Because air time is itself being managed and is a shared resource, air time rate limiting and policing applies to the

sum of downlink and uplink air time.

In summary, the goals of ATF are to provide:

1. The ability to specify medium access as a weighted allocation of air time instead of a specific bit rate, and to

make this ability available on a per-SSID, per-client type, and per-other basis

2. Application to all packets that go over the air, and not just data-frame payloads (for example, TCP, UDP, etc.)

ATF - Behavior

In order to control (or constrain) air time on a weighted basis, the air time (which includes both uplink and downlink

transmissions) of a client or SSID will be continuously measured.