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Occasional Contributor II

belated 5GHz SSID despite bss-table shows bss

Hi Guys

 

Something came to my eye recently after an update, and after some investigation, I came to the bottom of it.

 

After an AP reboot / Upgrade, the command "show ap bss-table" shows several 5 GHz bss, but it cannot be seen by clients. After some time (about 5-6 minutes) the ssid can be seen.

 

After asking around, some members of my team said they experienced the same, but only with 5 GHz SSID. And, it seems like it is like that from an 8.6 version onwards.

 

Did anyone experience something similar or has an explanation for it? Because, if I remember correctly, because of regulatory, the 5 GHz must wait and scan for one minute and then goes up contrary to the 2.4 GHz Band.

 

We're running a standalone Wireless controller with now version 8.6.0.3, but some colleagues also saw it on MM/MD constructs as well.

 

Best Regards


Accepted Solutions
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MVP

Re: belated 5GHz SSID despite bss-table shows bss

This sounds like the 5Ghz radio observing mandatory wait times before using a DFS channel ? show ap active has a flag which indicates the radio is in this status: Q = DFS CAC timer running; Channel Availability Check Time: The time a system shall monitor a channel for presence of radar prior to initiating a communications link on that channel Defined by the ETSI EN 301 893 standard, the CAC is 60 seconds, but some frequencies require 10 Minutes. NOTE 1: For channels whose nominal bandwidth falls completely or partly within the band 5 600 MHz to 5 650 MHz, the Channel Availability Check Time shall be 10 minutes. The SSID appears after what seems like 5-6 minutes because the timer has started 4-5 minutes prior to the display time being established. This behavior is common to all Aruba (in fact all 802.11 compliant products) products and versions, the CAC time may change based on the newest ETSI standard. If you observe what appears to be problematic behavior, take a look at the ap tech-support logs (contain driver specific log entries about radio status) and the output of "show ap active" and "show ap bss-table".
Shawn Adams
Aruba Networks Customer Advocacy

View solution in original post


All Replies
Highlighted
MVP

Re: belated 5GHz SSID despite bss-table shows bss

This sounds like the 5Ghz radio observing mandatory wait times before using a DFS channel ? show ap active has a flag which indicates the radio is in this status: Q = DFS CAC timer running; Channel Availability Check Time: The time a system shall monitor a channel for presence of radar prior to initiating a communications link on that channel Defined by the ETSI EN 301 893 standard, the CAC is 60 seconds, but some frequencies require 10 Minutes. NOTE 1: For channels whose nominal bandwidth falls completely or partly within the band 5 600 MHz to 5 650 MHz, the Channel Availability Check Time shall be 10 minutes. The SSID appears after what seems like 5-6 minutes because the timer has started 4-5 minutes prior to the display time being established. This behavior is common to all Aruba (in fact all 802.11 compliant products) products and versions, the CAC time may change based on the newest ETSI standard. If you observe what appears to be problematic behavior, take a look at the ap tech-support logs (contain driver specific log entries about radio status) and the output of "show ap active" and "show ap bss-table".
Shawn Adams
Aruba Networks Customer Advocacy

View solution in original post

Highlighted
Occasional Contributor II

Re: belated 5GHz SSID despite bss-table shows bss

Hi Shawn

 

Thank you for your input, I will check that definitely.

 

Regards

René

Highlighted
Occasional Contributor II

Re: belated 5GHz SSID despite bss-table shows bss

Hi Shawn

 

Once again, you are absolutely right. I have replicated the issue and exactly as the Q flag disappeared, the BSS was visible.

 

Thank you again for your invaluable expertise.

Regards

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