IEEE 11-21/0396r4 MLD Architecture Discussion
This document presents architecture concepts for TGbe MLDs, focusing on AP and non-AP considerations. It builds upon previous ideas and agreements from ARC sessions, offering insights and ongoing discussions within the ARC group. Various implementation choices and AP data plane discussions are included, shedding light on key aspects of IEEE 802.11 standards and legacy operation additions.
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June 2021 doc.: IEEE 11-21/0396r4 802.11be MLD Architecture Discussion Date: 2021-06-17 Authors: Name Mark Hamilton Affiliations Address Ruckus/CommS cope Phone +1-303-818-8472 email mark.hamilton@commsco pe.com 350 W. Java Dr Sunnyvale, CA 94089 Sli de 1 Submission Slide 1 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 Abstract This presentation considers architecture concepts for TGbe MLDs, AP and non-AP. This is follow-on from ideas in 11-20/1639, and starts from assumptions/agreements from ARC sessions from Nov 20 through Feb 21, in that document. The contents here are from ongoing discussions in the ARC group, and are still open discussions (TBDs, questions/question marks/TBRs are actions for the ARC group) Sli de 2 Submission Slide 2 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 (U) (C) IEEE 802.1X Controlled and Uncontrolled Port Filtering (optional) (M) MLD data plane agreed model RX/TX MSDU Rate Limiting A-MSDU Aggregation (TX) / De-aggregation (RX) PS Defer Queuing (AP or IBSS STA only) (null) (See also, slide 9 of 11-21/0316r0) Sequence Number Assignment (null) MSDU Integrity and Protection (optional) MLD-level Fragmentation (TX) / Defragmentation (RX) Packet Number Assignment Replay Detection (optional) SYNRA Receiver Filtering (null) Block Ack Buffering and Reordering (null) MPDU Encryption (TX) / Decryption (RX) and Integrity (optional) Duplicate Detection (null) Sli de 3 Implementation choice Block Ack Scoreboarding (null) Address 1 address filtering Address 1 address filtering (null) (null) . . . MPDU Header + CRC Creation (TX) / Validation (RX) MPDU Header + CRC Creation (TX) / Validation (RX) Per-link-level A-MPDU A-MPDU Aggregation (TX) / De-aggregation (RX) Aggregation (TX) / De-aggregation (RX) Submission Slide 3 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 AP Data plane w/legacy operation added (Alt 2 of 11-20/1639) Legacy Data frames MLO Data frames Legacy Data frames Upper legacy & group addressed MAC (legacy peer STAs and all groupcast) Upper legacy & group addressed MAC (legacy peer STAs and all groupcast) Upper MLD MAC (MLD peer STAs individually addressed) . . . Lower MAC, and PHY (MLO and legacy) Lower MAC, and PHY (MLO and legacy) Sli de 4 Link 1 BSS Link 2 BSS Mixed (MLO & legacy) Mixed (MLO & legacy) Submission Slide 4 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 Reminder of (legacy) DS structure, Figure 7-1, in 802.11-2020 DSAF DSAF DSAF Mesh MAC PHY Portal MAC MAC MAC MAC PHY MAC DS PHY PHY PHY PHY 802.11 Medium 802.11 Medium 802.11 Medium Non-802.11 Medium Non-AP STAs AP1 Mesh Gate Portal AP2 - DS SAP Sli de 5 Submission Slide 5 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 MLO DS structure Multi-Link Device DSAF DSAF MLD Upper DSAF Portal MAC Legacy Upper Legacy Upper DS PHY Non-802.11 Medium Lower Lower Portal 802.11 Medium 802.11 Medium - DS SAP Link 2 Link 1 Sli de 6 multi-link device (MLD): A device that is a logical entity and has more than one affiliated station (STA) and has a single medium access control (MAC) service access point (SAP) to logical link control (LLC), which includes one MAC data service. Submission - Each stack has a MAC SAP, which (on an AP) supports a DSAF, with a DS SAP Slide 6 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 Add (ML) management operations, and consider the stack details: Legacy Data frames MLD Data frames Legacy Data frames (U) (C) (U) (C) (U) (C) IEEE 802.1X IEEE 802.1X IEEE 802.1X Controlled and Uncontrolled Port Filtering (optional) (M) Controlled and Uncontrolled Port Filtering (optional) (M) TX Action frames Controlled and Uncontrolled Port Filtering (optional) (M) RX Action frames RX/TX MSDU Rate Limiting RX/TX MSDU Rate Limiting RX/TX MSDU Rate Limiting Beacons, Probe Req/Resp; and Control frames (RTS/CTS, Ack, NDP, etc) Beacons, Probe Req/Resp; and Control frames (RTS/CTS, Ack, NDP, etc) A-MSDU A-MSDU A-MSDU Aggregation (TX) / De-aggregation (RX) Aggregation (TX) / De-aggregation (RX) Aggregation (TX) / De-aggregation (RX) RX Assoc, etc frames TX Assoc, etc frames PS Defer Queuing (AP or IBSS STA only) PS Defer Queuing (AP or IBSS STA only) PS Defer Queuing (AP or IBSS STA only) (null) (null) (null) Sequence Number Assignment Sequence Number Assignment Sequence Number Assignment (null) (null) (null) MSDU Integrity and Protection (optional) MSDU Integrity and Protection (optional) MSDU Integrity and Protection (optional) Fragmentation (TX) / Defragmentation (RX) Fragmentation (TX) / Defragmentation (RX) Fragmentation (TX) / Defragmentation (RX) Packet Number Assignment Replay Detection (optional) Packet Number Assignment Replay Detection (optional) Packet Number Assignment Replay Detection (optional) SYNRA Receiver Filtering SYNRA Receiver Filtering SYNRA Receiver Filtering (null) (null) (null) Block Ack Buffering and Reordering Block Ack Buffering and Reordering Block Ack Buffering and Reordering (null) (null) (null) MPDU MPDU MPDU Encryption (TX) / Decryption (RX) and Integrity (optional) Encryption (TX) / Decryption (RX) and Integrity (optional) Encryption (TX) / Decryption (RX) and Integrity (optional) (null) Duplicate Detection (null) Duplicate Detection (null) Duplicate Detection Block Ack Scoreboarding Block Ack Scoreboarding Block Ack Scoreboarding (null) (null) (null) Address 1 address filtering Address 1 address filtering (null) (null) . . . . . Sli de 7 MPDU Header + CRC Creation (TX) / Validation (RX) MPDU Header + CRC Creation (TX) / Validation (RX) A-MPDU A-MPDU Aggregation (TX) / De-aggregation (RX) Aggregation (TX) / De-aggregation (RX) Physical Layer Physical Layer Link 1 BSS Link 2 BSS Mixed (MLO & legacy) Mixed (MLO & legacy) Submission Slide 7 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 To add management concepts, we have this figure as the fundamental reference model for a STA (Figure 4-24 in 802.11-2020) This adds MLME, PLME, SME concepts, and their SAPs - 802.1X Authenticator / Supplicant 802.1X MAC SAP RSNA Key Management MAC Sublayer Management Entity Data Link Layer MAC Sublayer MLME SAP MLME-PLME SAP PHY SAP Station Management Entity PHY Sublayer Management Entity Sli de 8 Physical Layer PLME SAP PHY Sublayer Do we want/need a similar reference model for MLDs? Submission Slide 8 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 IEEE 802.1X Authenticator or Supplicant MLD Management RSNA Key Management IEEE 802.1X MAC SAP MAC Sublayer A MAC Sublayer Management Entity MAC Sublayer Management Entity MAC Sublayer B MAC Sublayer B PHY SAP PHY SAP MLME-PLME SAP MLME-PLME SAP PHY Management Entity PHY Management Entity PHY PHY SME SME STA 1 STA 2 (e.g., in 2.4 GHz) (e.g., in 5 GHz) Figure xxx Reference model for an MLD Suggest this was a bad idea raises many questions about what is this part ? Why isn t the MAC SAP at the top? Are there always exactly two STAs, Etc Submission Slide 9 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 802.1X MLD Management Authenticator / Supplicant RSNA Key Management IEEE 802.1X MAC SAP MAC Sublayer A MAC Sublayer Management Entity MAC Sublayer Management Entity MAC Sublayer B MAC Sublayer B PHY SAP PHY SAP MLME-PLME SAP MLME-PLME SAP PHY Management Entity PHY Management Entity PHY PHY SME SME STA 1 STA 2 (e.g., in 2.4 GHz) (e.g., in 60 GHz) Is this better, or still confusing? Submission Slide 10 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 Is this any better (or is it worse)? (U) (C) 802.1X MAC SAP (U) (C) (U) (C) 802.1X MAC SAP 802.1X MAC SAP Legacy upper MAC Legacy Upper MLME (U) (C) 802.1X MAC SAP Legacy Upper MLME Legacy upper MAC 802.1X Authenticator / Supplicant MLD Upper MAC MLD Upper MLME Legacy upper MAC Legacy Upper MLME MLME SAP MLME SAPs RSNA Key Management SME (MLD aware) Lower MAC Lower MLME Lower MAC Lower MLME Lower MAC PHY SAP Lower MLME MLME SAPs PLME PHY SAP PHY PHY SAP PLME PHY PLME SAPs PLME PHY Sli de 11 (N) Channels or bands Other suggestions? Submission Slide 11 Mark Hamilton, Ruckus/CommScope
June 2021 doc.: IEEE 11-21/0396r4 What about non-AP? Non-AP is always either MLO or legacy So, no combined view. It s either one or the other: Upper MLD MAC Upper MLD MAC Sli de 12 . . . Lower MAC, and PHY Lower MAC, and PHY Lower MAC, and PHY Submission Slide 12 Mark Hamilton, Ruckus/CommScope
June 2021 Analysis of stack details what is where? doc.: IEEE 11-21/0396r4 Security SAs/Keys (In MLO, agreement, there is 1 PTK/PMK per MLD- MLD (P2P) association , managed by MLD stack) (GTKs are distributed via MLD-MLD association) PTK/PMK: - MLO: PTK/PMK in MLD stack; - Legacy: legacy stack s PTK/PMK; GTK, IGTK, BIGTK: in each legacy stack - (Any use case for pre-assoc Security SA (and PMKID) that needs to work post-assoc?) (Re)(Dis)Association, (De)Authentication AP: Routing RX d to which stack is based on ML element indication (legacy or MLO) Authenticator(s) 1 per legacy + 1 for MLD (At least separate Authenticator IDs (AAs)) Sli de 13 Submission Slide 13 Mark Hamilton, Ruckus/CommScope
June 2021 Analysis of alternatives what is where; what is different? doc.: IEEE 11-21/0396r4 Address1 filter/RX frame routing The value of the RA/TA fields sent over-the-air in the MAC header of a frame is the MAC address of the STA affiliated with the MLD corresponding to that link. [Motion 108, [30] and [186]] MLD Peer -> MLD (known by association) Legacy Peer -> Legacy stack Unassoc Peer -> Legacy stack (All RX d frames, data, Auth/Assoc, Mgmt, etc.) Note: - Power Save affecting information: PM bit, PS-Poll frames, PS trigger frames handled by coordination. - MLD knows when all links (or all relevant-TID links) are dozing, and buffers DL SAP(s) AP: 1 MLD, 1 per legacy guarantees frame order w/in TS (DS is responsible for routing DL) - Note: to guarantee frame order, without block ack, can t do cross-link parallel transmit/queuing. Sli de 14 Non-AP: Consistent MAC address (MLD or legacy) Submission Slide 14 Mark Hamilton, Ruckus/CommScope
June 2021 Analysis of alternatives what is where; what is different? doc.: IEEE 11-21/0396r4 Alternative 2 Beacons; Probes All go to/from legacy stack (but legacy stack will add ML-element, as appropriate) TIM bits? TBD Robust management frames Individually addressed just works (PTK) Group addressed? Are there any MLD (not link-related/link-specific) group addressed management frames? GAS/ANQP (Pre-Assoc or post-Assoc) Given security and RX routing above, just works. (Pre-assoc is legacy, post-assoc is usual rules.) QoS(EDCA) queues/retry buffers (includes how to merge TX traffic at the lower MAC boundary implementation choice) EDCA queues per lower MAC. Retries can stay in their queue (same link), or can be moved to another link (where in the queue is implementation choice). Sli de 15 ?? (Is it required, to handle frame ordering across links?) Block Ack Submission Slide 15 Mark Hamilton, Ruckus/CommScope
June 2021 Analysis of alternatives what is where; what is different? doc.: IEEE 11-21/0396r4 Alternative 2 MLO channel configuration/modification of operation SN and PN (including QMF) Number spaces per stack need MLO RXr to keep separate DMS Legacy peer: as today; MLO peer: messy Multiple BSSID sets Are legacy and MLD stacks separate multiple BSSs ? Any impacts on DS interface? Separate SAPs so what (??) What is an ESS/BSS? (In MLO, transitions to/from MLO) Sli de 16 BSS transition ( AP roaming ) group address frames How is this different/more complicated than legacy case? Multiple DTIM timings Submission Slide 16 Mark Hamilton, Ruckus/CommScope
June 2021 Analysis of alternatives what is where; what is different? doc.: IEEE 11-21/0396r4 Alternative 2 Access Controls? Multi-AP coordination? (Mixed-mode) Mesh? Relays? OCB? TDLS? Group membership for group addressed frames? Sli de 17 Submission Slide 17 Mark Hamilton, Ruckus/CommScope
