RSTP priority vector and role selection

最新推荐文章于 2023-05-04 18:16:36 发布

原创最新推荐文章于 2023-05-04 18:16:36 发布 · 1.9k 阅读

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博客围绕Priority vector展开，介绍了Per Bridge、Per Port、Per BPDU下不同的Priority vector形式，如bridge priority vector、root priority vector等。还阐述了Priority vector的更新以及Port Role Selection state machine中根据不同条件设置端口角色的规则。

Priority vector

Per Bridge

bridge priority vector = {B:0:B:0:0}

root priority vector = {B:0:B:0:0} or

= {RD:RPCD+PPCPB:D:PD:PB}

Per Port

root path priority vector = {RD:RPCD+PPCPB:D:PD:PB}

designated priority vector = {B:0:B:QB:QB} or

= {RD:RPCD+PPCPB:D:QB:QB}

port priority vector

Per BPDU

message priority vector = {RD:RPCD:D:PD:PB}

Priority vector update

Port Role Selection state machine

If the message which has been received is aged out on the port, it is set to DesignatedPort (infoIs=Aged)

If the bridge is root or port priority is derived from another port on the bridge, the ports is set to DesignatedPort (infoIs =Mine)

If root priority vector is derived from the port which is set to RootPort (infoIs=Received)

If designated priority vector is higher than port priority vector for the port which is set to DesignatedPort (infoIs=Received)

If designated priority vector is not higher than port priority vector for the port and the designatedBridgeID is this Bridge, then the port is set to BackupPort (infoIs=Received)

If designated priority vector is not higher than port priority vector for the port and the designatedBridgeID is not this Bridge, then the port is set to AlternatePort (infoIs=Received)