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Use of BSSID in WAVE

Use of BSSID in WAVE. Authors:. Date: 2007-11-15. Abstract. It is proposed to set the BSSID in all data frames transmitted in WAVE mode to the wildcard BSSID. This is to permit simultaneous reception of WAVE BSS data frames and non-BSS data frames on the same channel. Desired Functionality.

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Use of BSSID in WAVE

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  1. Use of BSSID in WAVE Authors: Date: 2007-11-15 Doug Kavner, Raytheon

  2. Abstract It is proposed to set the BSSID in all data frames transmitted in WAVE mode to the wildcard BSSID. This is to permit simultaneous reception of WAVE BSS data frames and non-BSS data frames on the same channel. Doug Kavner, Raytheon

  3. Desired Functionality • WAVE mode permits transmission of data frames without an established WAVE BSS • Normally with a wildcard BSSID • It may be desirable now or in the future to permit this in conjunction with WAVE BSS data frames from the same STA • 802.11p does not explicitly exclude this operation currently • Note: BSSID for a WAVE BSS is the MAC address of the WAVE BSS Initiator Doug Kavner, Raytheon

  4. The Problem (1) • BSSID in transmitted data frames is the currently joined BSSID • BSSID is not specified on a frame-by-frame basis from higher layers • See IEEE Std 802.11-2007, clause 6.2.1.1.2 • Adding a frame specific BSSID would require changing MA-UNITDATA.request and may not be supportable on current implementations • Resetting the MAC to change the BSSID is not feasible • Loss of MAC state and queued packets • Latency • Creating a MLME-SET-BSSID.request to change the BSSID without resetting the MAC would require tight coupling and synchronization of management and data planes Doug Kavner, Raytheon

  5. The Problem (2) • Using a non-wildcard WAVE BSSID for non-BSS data frames is problematic • Assume two nearby WAVE BSSs with BSSID=3 and BSSID=4 • STAs on BSSID 3 will filter data frames from BSSID 4 • Non-BSS data frames sent from a STA on BSSID 4 will also be filtered by STAs on BSSID 3 • Running in promiscuous mode would circumvent the primary purpose of multiple BSSIDs, which is to permit filtering of broadcast/multicast data frames • IEEE Std 802.11-2007, p. 78 first sentence Doug Kavner, Raytheon

  6. Solution #1 • Set BSSID in the MAC Header to the wildcard BSSID when: • DA/RA is a locally administered multicast address with the non_bss_multicast_bit = 1 (non_bss_multicast_bit is an arbitrary value to be selected by the editor) • Broadcast MAC address (FF FF FF FF FF FF) qualifies as a locally administered multicast address with non_bss_multicast_bit = 1 • Justification: We can partition the locally administered address space however we like • Implications to filtering of WAVE BSS Data Frames • Unicast Data Frames: None • Filtering is already based on the RA alone • Broadcast Data Frames: Filtering not supported • Use a specific multicast address instead • Multicast Data Frames: Filtered if non_bss_multicast_bit = 0 • Case of non_bss_multicast_bit = 0 when not joined to a WAVE BSS is undefined • Note that to/from DS data frames are sent unicast Doug Kavner, Raytheon

  7. Additional changes for Solution #1 • Need to footnote Table 7-7 in IEEE Std 802.11-2007 • For “From DS” frame, TA ≠ BSSID when the BSSID is wildcarded • For “To DS” frame, RA ≠ BSSID when the BSSID is wildcarded Doug Kavner, Raytheon

  8. Solution #2 • Add new MA-UNITDATA-NON-BSS.request/confirm/indication primitives to support transmission of data frames outside of a BSS • Parameters same as for MA-UNITDATA.request/confirm/indication • BSSID in MAC Header always set to wildcard BSSID • Permits a non-wildcard BSSID to be used for data frames sent with current MA-UNITDATA.request • Implications to filtering of WAVE BSS Data Frames • All traditional filtering methods supported • Requires higher layers to know which primitive to invoke • Non-BSS data frames are WSMP only • Enhance WSMP to have knowledge of the new primitive • On receive, MAC invokes MA-UNITDATA-NON-BSS.indication if the BSSID is the wildcard BSSID Doug Kavner, Raytheon

  9. Motion #1 • Move to accept solution #1 and instruct the editor to make updates to the draft • Moved: • Second: • For: • Against: • Abstain: Doug Kavner, Raytheon

  10. Motion #2 • Move to accept solution #2 and instruct the editor to make updates to the draft • Moved: • Second: • For: • Against: • Abstain: Doug Kavner, Raytheon

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