Channelfly and DFS channels - offline for 60 seconds?

Question

DFS channels require the AP to listen quietly for 60 seconds before using the channel. In the case when Channelfly is enabled, wouldn't this mean that when switching to a DFS channel, the AP essentially has to go offline for 60 seconds before coming back online again? This would have a significant impact on VoIP applications

unknown · Answer

AFAIK, it does not matter which feature or algo triggers the channel change, if DFS channel is selected, AP MUST go invisible for 60 seconds. this 60 second  is nothing but Channel Availability Check Time or DFS wait period where presence of radar is checked prior to initiating a communications link on that new channel (ch 104 in this case).

this is as per DFS regulation which every OEM MUST follow.

http://www.nts.com/pdf/whitepapers/6_...

i hope this helps.

unknown · Answer

Resurrecting this thread as I'm not seeing the behavior described, Keith - I likewise have a standalone 7982 with channelfly and DFS channels enabled, and I actually do see the AP go invisible for 60 seconds after a channel switch.  Here's an example syslog from the AP showing my STA dropping off after channel switch, followed by ~1 min of silence (on the STA side I see the network disappear):

May  7 04:13:41 RuckusAP daemon.info channel-wifi1: channelfly on radio 11a/n switches from channel 157 to channel 104

May  7 04:13:43 RuckusAP user.warn kernel: Start DFS wait period for channel 104

May  7 04:13:43 RuckusAP daemon.info hostapd: wlan8: STA c8:e0:eb:18:f3:13 IEEE 802.11: disassociated

May  7 04:13:43 RuckusAP daemon.warn Eved: STA-DISASSOC-REASON,nimac=c8:e0:eb:18:f3:13,func=sta_disassoc,line=2207,hint=AP VAP state change (RUN->INIT or SCAN),rx_rssi=36,ack_rssi=0,reason=0,freq=5785,chan=157,stats=(551,83357,470,109137)

May  7 04:13:43 RuckusAP daemon.warn Eved: wifi1: CHANNEL-CHANGE.indication: Channel (104)

May  7 04:14:47 RuckusAP user.warn kernel: End of DFS wait period

unknown · Answer

Keith, my experience has been that when channelfly is enabled and dfs channels are being selected amongst, latency sensitive applications are VERY MUCH IMPACTED, but not for 60 seconds clearly.

i have black-listed all DFS channels on my standalone 7982, as i simply can't tolerate the latency impacts...