Wireless Access

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Occasional Contributor II
Posts: 88
Registered: ‎12-27-2012

BSSID for the SSID

Hi Everyone,

 

I would like to know how BSSID is calculated based on the AP MAC address?

 

Are the calculations vary depends on the radio interface of the AP?

 

If anyone explains with the full calculation in detail then it will be really helpful.

 

Thanks in advance.

MVP
Posts: 4,271
Registered: ‎07-20-2011

Re: BSSID for the SSID


Somebody provided this to me awhile ago

 

First Step:
The controller takes the OUI and simply uses it as the first 6 characters of the BSSID 00:0b:86:

 

Second Step:
This is the interesting part. The controller first takes the next character and simply removes it.  6
The next character is then taken  6
A Boolean XOR is performed using this character and the value Hex 8, creating a new character  E

 

Third Step:
At this point the controller takes the next 3 HEX characters from the MAC address (characters 9-11)  0:da:
These 3 characters are appended to the first 7 characters, and these are the first 10 characters of the BSSID 00:0b:86:E0:da:

 

Fourth Step:
If the AP has 2 Ethernet ports and 2 Radios, then each Radio will be capable of a total of 16 BSSIDs
The 2.4 GHz radio will use the last HEX character of the wired Ethernet port for it's 11th character  3
The 2.4 GHz radio will begin assigning HEX values starting at 0 and incrementing to F for the 12th and final character 00:0b:86:E0:da:30 through 00:0b:86:E0:da:3F
The 5 GHz radio will increment the last HEX character of the wired Ethernet port by 1, and use it for it's 11th character 4
The 5 GHz radio will begin assigning HEX values starting at 0 and incrementing to F for the 12th and final character 00:0b:86:E0:da:40 through 00:0b:86:E0:da:4F

Thank you

Victor Fabian
Lead Mobility Engineer @ Integration Partners
AMFX | ACMX | ACDX | ACCX | CWAP | CWDP | CWNA
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