|Standard:||IEEE Std 802.1AS-2020||Clause:||10.3.15.3|
|Clause title:||State diagram|
Rationale for revision
It is intended that, when the state of a port is changed to TRUE, either as a result of invoking the BMCA or via external port configuration, an Announce message is immediately sent on that port. In the case where BMCA is used, this correctly occurs as follows: (1) the variable updtInfo is set to TRUE by the function updtStatesTree()(see 10.3.13.2.4) of the PortStateSelection state machine when the state of a port is set to MasterPort (see items (f)(3), (f)(4), and (f)(8) of 10.3.13.2.4). This in turn causes the variable newInfo to be set to TRUE in the UPDATE state of the PortAnnounceInformation state machine (see Figure 10-14). This in turn causes an Announce message to be transmitted in the PortAnnounceTransmit state machine (see the right branch out of the IDLE state of the PortAnnounceTransmit state machine, of Figure 10-18; note that the right branch was cut off from the figure when 802.1AS-2020 was published, but the submitter (i.e., the editor) has been informed that IEEE will publish an errata to fix this). However, in the case where external port configuration is used, the variable newInfo is not set to TRUE when the state of a port is set to MasterPort, which means that an Announce message will not be immediately sent when the port state is set to MasterPort. This is not correct. Specifically, newInfo should be set to TRUE if the state of the port is set to MasterPort via external port configuration. This should be done by the updtPortState(j) function (see 10.3.15.2.2) of the PortStateSettingExt state machine (see Figure 10-17).
(a) Add the following sentence to item (c)(3)of the updtPortState(j) function (see 10.3.15.2.2): If portStateInd is equal to MasterPort, set newInfo to TRUE. (b) In Figure 10-12, remove the variable newInfo from the arrow going from the PortAnnounceInformationExt block to the PortAnnounceTransmit block (note that newInfo is not set by the PortAnnounceInformationExt block). (c) In Figure 10-12, add the variable newInfo to the arrow going from the PortStateSetting block to the PortAnnounceTransmit block.
Impact on existing networks
This change will cause an Announce message to be sent as soon as the state of the port is set to MasterPort, when external port configuration is used. This is the correct and desired behavior.
|Name:||Geoffrey M. Garner||Email:||email@example.com|