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Re: [STDS-802-11-TGBN] Roaming TTT: 11-25/1982 doc on Urgent roaming

Hi Jay,

Thank you for your comment and question.

The SMD_Roaming_Key does not need to be installed in the HW. Processing of the ST direct request at the target AP can be done in SW and once direct roaming is successful then the newly derived PTK would get installed in the HW. This would avoid installing a large number of keys in the HW, but of course this will be left to implementation.

Thanks,
Binita

On Thu, Jan 8, 2026 at 6:07 PM Jay Yang <yang.zhijie@xxxxxxxxxx> wrote:

Hi Binita ,


Thanks for your efforts on this.


Regarding on the following proposed new text, I wonder when the target AP MLD install the SMD _Roaming _Key? Does it happened after any UHR STA associated with any AP MLD in the SMD ? If so, I'm afraid the SMD _Roaming_Key number will be equal to the UHR STA numbers in the same SMD , and that will be a huge memory cost on each AP MLD in a larger network. Please help clarify that, maybe I make some mistake.



If thePer-AP MLD PTK mode is used, an SMD _Roaming_Key is derived using  the SMD _KDKat the time of initial association to the SMD -ME.The SMD _Roaming_Key is an SMD level key that is used to encrypt ST direct request and response frames exchanged over-the-air directly between the non-AP MLD and the target AP MLD when Per-AP MLD PTK mode is used.

The SMD _Roaming_Keyis derived as below:

-       SMD _Roaming_Key = KDF -Hash-Length(SMD _KDK,“SMD Roaming Key”, Min(AA,SPA) || Max(AA,SPA) || Min(ANonce,SNonce) || Max(ANonce,SNonce) || SMD Identifier)

where,

-       KDF -Hash-Length is the key derivation function as defined in 12.7.1.6.2 (Key derivation function (KDF )) using the hash algorithm identified by the corresponding AKM .

-       Length is the total number of bits to derive, i.e., number of bits of theSMD_Roaming_Keyand is equal to the length of the PTK .

-       The AA is the MLD MAC address of the AP MLD through which association to the SMD -ME occurs.






Thanks


Best Regards


Jay Yang (杨志杰)



Original
From: BinitaGupta <bingupta.ieee@xxxxxxxxx>
Date: 2026年01月08日 22:31
Subject: [STDS-802-11-TGBN] Roaming TTT : 11-25/1982 doc on Urgent roaming
Hi Roaming TTT members,
I have uploaded doc 11-25/1982 that resolves 12 CIDs related to supporting urgent roaming directly with a target AP MLD within an SMD .

Could you please review and provide any feedback you have.

@Alfred Asterjadhi  - could you please add following to the TGbn MAC agenda.

  • 11-25/1982 (12 CIDs ) 


Thanks,
Binita

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