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Dynamic Frequency Selection
End-user commands are as follows:
• config mesh astools [enable | disable]—Enables or disables the astools on the mesh access points. If
• show mesh astools stats—Shows the list of stranded APs and their listeners if they have any.
• debug mesh astools troubleshoot mac-addr start—Sends a message to the best neighbor of the mac-addr
• debug mesh astools troubleshoot mac-addr stop—Sends a message to the best neighbor of the mac-addr
• clear mesh stranded [all | mac of b/g radio]—Clears stranded AP entries.
The controller console is swamped with debug messages from stranded APs for 30 minutes.
Dynamic Frequency Selection
This section describes the Dynamic Frequency Selection (DFS) functionality in RAP and MAP.
DFS in RAP
The RAP performs the following steps as a response to radar detection:
1 The RAP sends a message to the controller that the channel is infected with radar. The channel is marked
as infected on the RAP and on the controller.
2 The RAP blocks the channel for 30 minutes. This 30-minute period is called the nonoccupancy period.
3 The controller sends a TRAP, which indicates that the radar has been detected on the channel. A TRAP
remains until the nonoccupancy period expires.
4 The RAP has 10 seconds to move away from the channel. This period is called the channel move time,
which is defined as the time for the system to clear the channel and is measured from the end of the radar
burst to the end of the final transmission on the channel.
5 The RAP enters the quiet mode. In the quiet mode, the RAP stops data transmissions. Beacons are still
generated and probe responses are still delivered. The quiet mode exists until the channel move time is
over (10 seconds).
6 The controller picks up a new random channel and sends the channel information to the RAP.
7 The RAP receives the new channel information and sends channel change frames (unicast, encrypted) to
the MAP, and each MAP sends the same information to its lower children down the sector. Each mesh
access point sends the channel change frames once every 100 msecs for a total of five times.
8 The RAP tunes to the new channel and enters into the silent mode. During the silent mode, only the receiver
is ON. The RAP keeps scanning the new channel for any radar presence for 60 seconds. This process is
called channel availability check (CAC).
9 The MAP tunes to the new channel and enters into the silent mode. During the silent mode, only the
receiver is ON. The MAP keeps scanning the new channel for any radar presence for 60 seconds.
10 If radar is not detected, the RAP resumes full functionality on this new channel and the whole sector tunes
to this new channel.
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disabled, APs no longer sends a stranded AP list to the controller.
to start listening.
to stop listening.
Troubleshooting
OL-27593-01
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Table of Contents
Troubleshooting
