【正文】
而端口 Ether 0/3就會被阻塞,端口配置消息也不作改變,同時該端口不接收從 Switch A轉(zhuǎn)發(fā)的數(shù)據(jù)(不包括 STP的協(xié)議報文),直到新的情況發(fā)生觸發(fā)生成樹的重新計算,比如從 Switch B到 Switch C的鏈路 down掉,或者端口收到更優(yōu)的配置消息。 端口 Ether 0/3收到 Switch A的配置消息, Switch C發(fā)現(xiàn)本端口的配置消息優(yōu)先級低于接收到的配置消息的優(yōu)先級,于是更新本端口 Ether 0/3的配置消息。 Switch B發(fā)現(xiàn)自己各個端口的配置消息中樹根和指定交換機都是自己,則認為自己是樹根,各個端口的配置消息都不作任何修改,以后周期性的向外發(fā)送配置消息。 5 配置舉例 [SwitchA]display stp interface ether0/1 ether0/3 Protocol mode: IEEE RSTP The bridge ID (): The bridge times: Hello Time 2 sec, Max Age 20 sec, Forward Delay 15 sec Root bridge ID(): Root path cost: 200 Bridge bpduprotection: disabled Timeout factor: 3 Port 1 (Ether0/1) of bridge is Forwarding Port spanning tree protocol: enabled Port role: Root Port Port path cost: 200 Port priority: 128 Designated bridge ID(): The Port is a nonedged port Connected to a pointtopoint LAN segment Maximum transmission limit is 3 Packets / hello time Times: Hello Time 2 sec, Max Age 20 sec Forward Delay 15 sec, Message Age 0 BPDU sent: 4 TCN: 0, RST: 4, Config BPDU: 0 BPDU received: 458 TCN: 0, RST: 458, Config BPDU: 0 5 配置舉例 Port 3 (Ether0/3) of bridge is Forwarding Port spanning tree protocol: enabled Port role: Designated Port Port path cost: 200 Port priority: 128 Designated bridge ID(): The Port is a nonedged port Connected to a pointtopoint LAN segment Maximum transmission limit is 3 Packets / hello time Times: Hello Time 2 sec, Max Age 20 sec Forward Delay 15 sec, Message Age 1 BPDU sent: 563 TCN: 0, RST: 563, Config BPDU: 0 BPDU received: 5 TCN: 0, RST: 5, Config BPDU: 0 5 配置舉例 交換機的比較過程 ( Switch B ) 端口 Ether 0/1收到 Switch A的配置消息, Switch B發(fā)現(xiàn)本端口的配置消息優(yōu)先級高于接收到的配置消息的優(yōu)先級,就把接收到的配置消息丟棄。端口 Ether 0/3配置消息中,樹根 ID更新為最優(yōu)配置消息中的樹根 ID,根路徑開銷更新為 200,指定交換機 ID更新為本交換機 ID,指定端口 ID更新為本端口 ID,配置消息變?yōu)椋?{, 200, ,e0/3}。 端口 Ether 0/3收到 Switch C的配置消息, Switch A發(fā)現(xiàn)本端口的配置消