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Description of the DSBM Election Algorithm
Article ID: 247101 - View products that this article applies to.
This article was previously published under Q247101
The protocol for electing and discovering Designated Subnet Bandwidth Manager (DSBM) is named the DSBM election Protocol. To allow for a timely recovery from a DSBM failure, it may be useful to have additional Subnet Bandwidth Managers active on the segment for fault tolerant purposes. After a DSBM is recognized, the remaining Subnet Bandwidth Managers remain passive on the network only until it is necessary to start an election.
For algorithm purposes, a Subnet Bandwidth Manager (SBM) is in one of the following four states:
An SBM is idle only when there is not an election process and the DSBM is already elected. If the DSBMDeadInterval is reached (meaning no I_AM_DSBM messages were received by active SBMs), then the SBM candidates would go in to the ElectDSBM state after sending out a DSBM_WILLING message. Also, if the DSBM is shut down, it sends out a DSBM_WILLING message. During this process, SBM priority is set to 0 to remove itself from the election and then require an election between other DSBM candidates. For additional information about related topics, click the article numbers below to view the articles in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/228830/EN-US/ )Description of Subnet Bandwidth Manager (SBM) in Windows 2000
(http://support.microsoft.com/kb/247102/EN-US/ )DSBM Election Algorithm