Hi Jarkko,
Thanks for your response. At least I see it’s possible that we could reach some consensus and move forward. See my response in blue font.
Thanks
Best Regards
Jay Yang
From: Jarkko Kneckt <jkneckt@xxxxxxxxx>
Sent: 2023年2月25日 1:34
To: Zhijie Yang (NSB) <zhijie.yang@xxxxxxxxxxxxxxx>
Cc: STDS-802-11-TGBH@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBH] RRCM versus e-RRCM for TGbh motion on Feb 28
Hi Jay, thank you for your comments.
Thanks for the comments, see my response inline.
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Are there aspects of e-RRCM that you oppose, and bringing those into the proposal that is put to motion next week would cause you to vote No?
1) RRCM and e-RRCM allow STA to use only MAC addresses that are calculated by using RMAK.
- This limits STA operation flexibility to freely select its MAC address.
àBased on 11aq, each STA calculates its RMA based on one private equation. In e-RRCM, both side calculate the same RMAs based on the pre-defined equation, it’s
easy for implementor to switch from private equation to the pre-defined equation. Anyway, If you have a strong concern on the MAC based solution, we can move it to the IE element. The purpose of the generated RMA is to find the right key on both side in e-RRCM
solution, no matter it’s MAC address or other staff.
JKN: IE based solution would be much better than MAC address based solution.
The STA has selected its MAC address and this selection is widely deployed.
The use of IE would solve this comment.
<Jay> it will be grateful if the group can reach the consensus on this direction.
2) The use case for pre-association STA identification is not clear to me.
- What benefits does STA get if it identifies itself before association?
àWhen we talk some use cases like use case 4.8 and use case 4.26 etc. in last year, your guys also agree these cases should be addressed and updated them into
the latest use case tracking document, which is approved by the group with unanimous consensus.
Anyway, I’m happy to explain the benefit to the STA again, in order to get some STA vendor’s support.
If you look Link recommendation feature defined in the latest 11be draft, in which “An AP MLD may also use Multi-Link Traffic Indication element and AID Bitmap element in a Link Recommendation frame to recommend
a non-AP MLD to use one or more enabled links for all exchanges both for DL and UL”. Actually, Link recommendation inherits the spirt from Client steering/band steering function, in which AP provides the recommended candidate bands or Neighbor APs, so that
STA can obtain the better services on that AP/band. However, the Client steering/band steering is based on the BTM request/response frame change, while allow STA make the final decision. Please see the details in 818r2 “P5,
Client steering”
JKN: If I understand your response correctly, you are saying that main benefit of pre-associated STA identification is that network can steer the STA to operate on a network selected BSS, right?
- STA may have reasons to select a network that is not obvious for the AP. For instance, STA may have co-ex issues or operate P2P connection.
<Jay> The term of client steering or band steering is widely used in Wi-Fi industry, but the basic principle is that network provides the recommendation of the candidate AP. E.g. In our implementation, The network
will provide the candidate APs for mobility STA, It’s up to the STA to follow such recommendation or not.
The Link Recommendation and BSS Transition Management (BTM) can be used to steer
associated STAs.
Steering in associated state is much better for the STA, because the STA can send data and have time to select the AP for its association.
<Jay> The use case 4.8 is aligned what you are talking, it’s
a post-association client steering case indeed.
I do not know how the pre-associated STA steering will be done. I think 802.11 specification has no feature or signaling to steer such pre-associated STA.
- Only steering mechanism I can think is to fail the identified STA association. This is bad for the STA, because:
- STA does not know to which BSS it should associate
- Some networks may require STA identification to get access to the network. The device identification should be always optional.
<Jay> I see the similar concern from other members, I think we can drop this use case in this round, maybe need further talk in the feature. Do you have some suggestion to avoid AP/ESS to have such implantation?
- What benefits does STA get if it identifies itself before association?
-I do not see any response to this question. It seems that there are no benefits for the STA to be identified before association.
<Jay> use case 4.8 is an instance of BTM for associated STA, seems you don’t object this use case,
could you check that use case step by step, let we know which step is unreasonable or unacceptable?
3) RRCM, e-RRCM and Device ID are alternative, non-interworking, protocols to identify a device.
- Why Device ID is not enough? Device ID has been long time in 802.11bh draft.
àThe current Device ID is only carried in 4-WAY handshake, if the Device ID or other identifier can be carried in other frame, like triggered probe, it will address
a lot of implementation broken issue.
- STAs do a lot of passive scanning, so limiting probe responses does not work
<Jay> I don’t remember this group have such use case in the use case tracking document. Maybe some members mentioned it during the call, I saw other members also against it. I also hope the group drop this use
case in this round.
- The probe responses should be common for all STAs. Probe Responses may select the APs they advertise in Reduced Neighbor Report, but this information is common for all STAs.
<Jay> It’s case by case, if we’re talking use case 4.8, the candidate APs only collect the metric based on the *-LTF filed in the probe request, while the information in the probe
response is common for all STAs.
Further, for broadcast probe response, I agree all information should be same for all STAs. For unicast probe response, there may be some difference for each STAs due to some security
concern on AP side. E.g. In some mesh network, the SSID information is only seen for candidate backhaul STAs in the unicast probe response.
Further, Our chair Mark made a lot of interpretation on the use cases defined in 11bh PAR in the previous meeting, and seems the current Device ID approach can’t meet the requirement on any of them. It’s decided
by whether you want to see the group to finish the task group job in the following plenary meeting. Or we still have enough time, like use more than 1 years to analysis the PAR, analysis the use case from End to End perspective as Sid proposed during the call.
After the down-select procedure, Sid provided 4 extra requirements for pre-association identification scheme in the last call. Suppose some of “Apple funs” keep this position as well. If we insist to working on RRCM solution, I believe
“Apple funs” will strong against the down-select results. And the expected motion will be failure definitely.
May I request to go with e-RRCM solution which may meet the 4 extra requirements listed by Sid? I would like to hear the group’s opinion.
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Consent
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Unauthenticated environment
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Malicious 3rd party protection
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What is identifier used for
I took an action item to start this discussion on the reflector…
On today’s call, we completed our down-selection process and settled on RRCM as the favored solution to work on, to try to get any additional solution into the Draft (or agree that we are not adding anything else). However, in discussion
following the down-selection process, it seems that some of the objection that might exist and prevent RRCM from passing such a motion, *might* be resolved by aspects of what’s in e-RRCM. So, we are left in a quandary – do we modify RRCM to include
some/all e-RRCM extensions to satisfy the concerns, or is that reversing our straw poll guidance that RRCM is preferred over e-RRCM, and therefore we’ll lose some RRCM supporting voters if we do so?
So, I’d like to start this thread to see if there is a sense in the group:
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Can those who preferred RRCM over e-RRCM provide an understanding of what made that decision for you?
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Are there aspects of e-RRCM that we can add to RRCM (to satisfy those who expressed concerns with RRCM as-is) and still hold your approval of RRCM going forward into the Draft?
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Are there aspects of e-RRCM that you oppose, and bringing those into the proposal that is put to motion next week would cause you to vote No?
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