Users Guide

Dell PowerConnect ArubaOS 5.0 | User Guide Access Points | 135
12. Enter 1 in the Channel text field and select the None radio button. In this instance, channel 1 is the assigned
20 MHz channel and 40 MHz mode is disabled and click Apply.
Configuring channels in the CLI
ap regulatory-domain-profile default
country-code US
rf dot11a-radio-profile ht-corpnet-a
channel 36+
rf dot11g-radio-profile ht-corpnet-g
channel 1
Automatic Channel and Transmit Power Selection Using ARM
To allow automatic channel and transmit power selection based on the radio environment, enable Adaptive Radio
Management (ARM). Note that ARM assignments will override the static channel and power configurations done
using the radio profile. For complete information on the Adaptive Radio Management feature, refer to Chapter 5,
“Adaptive Radio Management (ARM)” on page139.
APs Over Low-Speed Links
Depending on your deployment scenario, you may have APs or remote APs that connect to a controller located
across low-speed (less than 1 Mbps capacity) or high-latency (greater than 100 ms) links.
With low-speed links, if heartbeat or keep alive packets are not received between the AP and controller during the
defined interval, APs may reboot causing clients to re-associate. You can adjust the bootstrap threshold and
prioritize AP heartbeats to optimize these types of links. In addition, high bandwidth applications may saturate
low-speed links. For example, if you have tunnel-mode SSIDs, use them with low-bandwidth applications such as
barcode scanning, small database lookups, and Telnet to avoid saturating the link. If you have traffic that will
remain local, deploying remote APs and configuring SSIDs as bridge-mode SSIDs can also prevent link
saturation.
With high-latency links, consider the amount and type of client devices accessing the links. Dell APs locally
process 802.11 probe-requests and probe-responses, but the 802.11 association process requires interaction with
the controller.
Best Practices
When deploying APs across low-speed or high-latency links, Dell recommends the following:
z Connect APs and controllers over a link with a capacity of 1 Mbps or greater.
z Maintain a minimum link speed of 64 Kbps per GRE tunnel and per bridge-mode SSID. This is the minimum
speed required for downloading software images.
z Adjust the bootstrap threshold to 30 if the network experiences packet loss. This makes the AP recover more
slowly in the event of a failure, but it will be more tolerant to heartbeat packet loss.
z Prioritize AP heartbeats to prevent losing connectivity with the controller.
z If possible, reduce the number of tunnel-mode SSIDs. Each SSID creates a tunnel to the controller with its
own tunnel keep alive traffic.
z If most of the data traffic will remain local to the site, deploy remote APs in bridging mode. For more
information about remote APs, see Chapter 4, “Access Points” .
z If high-latency links such as transoceanic or satellite links are used in the network, deploy a controller
geographically close to the APs.
z If high-latency causes association issues with certain handheld devices or barcode scanners, check the
manufacturer of the device for recent firmware and driver updates.