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Hello All, I am attaching a presentation and associated late comment for today’s 802.3da meeting. I have identified a situation in which a new D-PLCA follower would collide with the coordinator BEACON. The D-PLCA coordinator attempts to retain size of the PLCA cycle such that the last Transmit Opportunity (TO) prior to the BEACON is always unused / unclaimed. The D-PLCA Coordinator only checks for the condition
when the aging period has elapsed and a new claim table is made active with old, expired TO claims removed from the claim table. Currently the aging period defaults to 64 PLCA cycles (BEACONS). The problem occurs when two new D-PLCA followers attempt to join the segment at the same time. The first follower will select the last unused TO of the cycle and transmit causing it to become claimed. The
second follower will select the first TO beyond the end of the cycle. When the second follower attempts to transmit it will then collide with the coordinator transmitting the BEACON. Please see the attached presentation. Regards, --
Tim Baggett Technical Staff Engineer - Applications --------------------------------------------------------------------------------- Microchip Technology, Inc. Networking and Connectivity Solutions (NCS) 8601 Ranch Rd 2222, Park Centre, Bldg. 3, Austin, TX 78730 Office: 512-334-8450 Tim.Baggett@xxxxxxxxxxxxx
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Attachment:
IEEE_802.3da_D3p1_Late_Comment_Baggett.xls
Description: IEEE_802.3da_D3p1_Late_Comment_Baggett.xls
Attachment:
Baggett_3da_LateCmt_DPLCA_Cycle_Increase_v01.pdf
Description: Baggett_3da_LateCmt_DPLCA_Cycle_Increase_v01.pdf