1.基本概念
STP收敛慢,端口定义繁琐,对网络拓扑变化依赖计时器。
RSTP(快速生成树)对STP进行了优化,收敛速度快,能兼容STP。
2.RSTP接口角色
包含根接口、指定接口、替代接口、备份接口。
1)替代接口
![图片[1]-7.2 RSTP-大赛人网](https://www.dsrw.com/wp-content/uploads/2023/03/图片3-7.png)
[SW3]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/2 ROOT FORWARDING NONE
0 GigabitEthernet0/0/3 ALTE DISCARDING NONE
GigabitEthernet0/0/3为阻塞接口,是根接口的备份。
2)备份接口
一台设备上由于收到了自己所发的BPDU从而被阻塞的接口。
3.RSTP接口状态
丢弃Discarding、学习Learning、转发Forwarding
4.边缘接口
连接终端设备的接口不需要参与STP生成树计算,可以设置为边缘接口(Edge Port),可以立即切换到转发状态。
![图片[2]-7.2 RSTP-大赛人网](https://www.dsrw.com/wp-content/uploads/2023/03/图片4-6.png)
[SW2]interface GigabitEthernet 0/0/1
[SW2-GigabitEthernet0/0/1]stp edged-port enable
[SW2]interface GigabitEthernet 0/0/2
[SW2-GigabitEthernet0/0/2]stp edged-port enable
[SW2]interface GigabitEthernet 0/0/3
[SW2-GigabitEthernet0/0/3]stp edged-port enable
5.P/A机制
RSTP通过Proposal/Agreement(提议/同意)机制保证一个指定接口从丢弃状态快速进入转发状态,加快了生成树收敛。
6.保护功能
1)BPDU保护
边缘接口收到BPDU后会变成一个普通接口,引发RSTP重新计算,影响网络,在交换机激活BPDU保护功能后如果边缘接口收到BPDU,则交换机会立即把接口关闭(Error-Down),并触发告警信息。
![图片[3]-7.2 RSTP-大赛人网](https://www.dsrw.com/wp-content/uploads/2023/03/图片5-6.png)
(1)边缘端口配置
[SW2]interface GigabitEthernet 0/0/1
[SW2-GigabitEthernet0/0/1]stp edged-port enable
[SW2]interface GigabitEthernet 0/0/2
[SW2-GigabitEthernet0/0/2]stp edged-port enable
[SW2]interface GigabitEthernet 0/0/3
[SW2-GigabitEthernet0/0/3]stp edged-port enable
(2)边缘端口激活BPDU保护配置
[SW2]stp bpdu-protection
[SW2]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/1 DESI FORWARDING BPDU
0 GigabitEthernet0/0/2 DESI FORWARDING BPDU
0 GigabitEthernet0/0/3 DESI FORWARDING BPDU
0 GigabitEthernet0/0/24 ROOT FORWARDING NONE
(3)BPDU保护接口自动恢复配置
手动恢复端口(undo shutdown)或设置自动恢复
[SW2]error-down auto-recovery cause bpdu-protection interval 30
2)根保护
根桥是可抢占的,重新计算RSTP会对网络造成影响,开启根保护功能会规避以上问题。
[SW1]interface GigabitEthernet 0/0/24
[SW1-GigabitEthernet0/0/24]stp root-protection
[SW1]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/24 DESI FORWARDING ROOT
3)环路保护
![图片[4]-7.2 RSTP-大赛人网](https://www.dsrw.com/wp-content/uploads/2023/03/图片6-6.png)
(1)RSTP基本配置
[SW1]stp mode rstp
[SW1]stp priority 0
[SW2]stp mode rstp
[SW3]stp mode rstp
[SW3]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/2 ROOT FORWARDING NONE
0 GigabitEthernet0/0/3 ALTE DISCARDING NONE
(2)指定接口配置环路保护
[SW3]interface GigabitEthernet 0/0/2
[SW3-GigabitEthernet0/0/2]stp loop-protection
[SW3]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/2 ROOT FORWARDING LOOP
0 GigabitEthernet0/0/3 ALTE DISCARDING NONE
(3)替代接口配置环路保护
[SW3]interface GigabitEthernet 0/0/3
[SW3-GigabitEthernet0/0/3]stp loop-protection
[SW3]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/2 ROOT FORWARDING LOOP
0 GigabitEthernet0/0/3 ALTE DISCARDING LOOP
(4)拓扑变更保护
[SW3]stp tc-protection
7.RSTP配置
![图片[5]-7.2 RSTP-大赛人网](https://www.dsrw.com/wp-content/uploads/2023/03/图片7-5.png)
1)RSTP基本配置
(1)基本配置
[SW1]stp mode rstp
[SW1]stp root primary
[SW1]stp enable
[SW2]stp mode rstp
[SW2]stp root secondary
[SW2]stp enable
[SW3]stp mode rstp
[SW3]stp enable
[SW4]stp mode rstp
[SW4]stp enable
[SW4]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/3 ALTE DISCARDING NONE
0 GigabitEthernet0/0/4 ROOT FORWARDING NONE
(2)修改GigabitEthernet 0/0/4COST值,配置GigabitEthernet 0/0/4为阻塞端口
[SW4]interface GigabitEthernet 0/0/4
[SW4-GigabitEthernet0/0/4]stp cost 100000
[SW4]display stp brief
MSTID Port Role STP State Protection
0 GigabitEthernet0/0/3 ROOT FORWARDING NONE
0 GigabitEthernet0/0/4 ALTE DISCARDING NONE
[SW4]display stp interface GigabitEthernet 0/0/4
-------[CIST Global Info][Mode RSTP]-------
CIST Bridge :32768.4c1f-cc04-10c3
Config Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
Active Times :Hello 2s MaxAge 20s FwDly 15s MaxHop 20
CIST Root/ERPC :0 .4c1f-cc28-59ea / 40000
CIST RegRoot/IRPC :32768.4c1f-cc04-10c3 / 0
CIST RootPortId :128.3
BPDU-Protection :Disabled
TC or TCN received :26
TC count per hello :0
STP Converge Mode :Normal
Time since last TC :0 days 0h:3m:2s
Number of TC :12
Last TC occurred :GigabitEthernet0/0/3
----[Port4(GigabitEthernet0/0/4)][DISCARDING]----
Port Protocol :Enabled
Port Role :Alternate Port
Port Priority :128
Port Cost(Dot1T ) :Config=100000 / Active=100000
Designated Bridge/Port :4096.4c1f-ccb4-211f / 128.4
Port Edged :Config=default / Active=disabled
Point-to-point :Config=auto / Active=true
Transit Limit :147 packets/hello-time
Protection Type :None
Port STP Mode :RSTP
Port Protocol Type :Config=auto / Active=dot1s
BPDU Encapsulation :Config=stp / Active=stp
PortTimes :Hello 2s MaxAge 20s FwDly 15s RemHop 0
TC or TCN send :1
TC or TCN received :3
BPDU Sent :2
TCN: 0, Config: 0, RST: 2, MST: 0
BPDU Received :208
TCN: 0, Config: 0, RST: 208, MST: 0
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