实例：

1.拓扑图

2.使用的是三层交换机的镜像

3.注意事项：

cisco 默认开启生成树协议

H3C 默认关闭

4.具体操作：

由于镜像是三层交换机的,所以要在每台交换机上执行

SW1(config)#no ip routing //关闭路由功能

SW3(config)#line console 0

SW3(config-line)#logging synchronous //日志同步

SW3(config-line)#no exec-timeout 0 0 //取消会话超时

SW1#show spanning-tree

VLAN1 is executing the ieee compatible Spanning Tree protocol

Bridge Identifier has priority 32768, address cc02.1aa8.0000

SW2#show spanning-tree

VLAN1 is executing the ieee compatible Spanning Tree protocol

Bridge Identifier has priority 32768, address cc04.1aa8.0000

SW3#show spanning-tree

VLAN1 is executing the ieee compatible Spanning Tree protocol

Bridge Identifier has priority 32768, address cc05.1aa8.0000

Configured hello time 2, max age 20, forward delay 15

SW1#show spanning-tree brief

VLAN1

Spanning tree enabled protocol ieee

Root ID Priority 32768

Address 000f.e21a.d4b1

Cost 38

Port 1 (FastEthernet0/0)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 32768

Address cc02.1aa8.0000

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300

Interface Designated

Name Port ID Prio Cost Sts Cost Bridge ID Port ID

-------------------- ------- ---- ----- --- ----- -------------------- -------

FastEthernet0/0 128.1 128 19 FWD 19 32768 cc04.1aa8.0000 128.1

FastEthernet0/1 128.2 128 19 FWD 38 32768 cc02.1aa8.0000 128.2

000f.e21a.d4b1 这个MAC地址不是我们搭建的交换机，而是受其他交换机的影响，所以，我们必须手动设置root id

SW1(config)#spanning-tree vlan 1 root primary //手动设置根

VLAN 1 bridge priority set to 8192

VLAN 1 bridge max aging time unchanged at 20

VLAN 1 bridge hello time unchanged at 2

VLAN 1 bridge forward delay unchanged at 15

SW1(config)#int f0/0

SW1(config-if)#shut

把SW1的f0/0再no shutdown 还可以恢复，中间也有间断（状态转换）

Blocking Listening learning forwarding

SW2(config)#int f0/1

SW2(config-if)#spanning-tree ?

cost Change an interface's spanning tree path cost

port-priority Change an interface's spanning tree priority

portfast Enable an interface to move directly to forwarding on link up

vlan VLAN Switch Spanning Tree

 

SW2(config-if)#spanning-tree portfast //连接主机的设为速端口

%Warning: portfast should only be enabled on ports connected to a single host.

Connecting hubs, concentrators, switches, bridges, etc.to this interface

when portfast is enabled, can cause temporary spanning tree loops.

Use with CAUTION

%Portfast has been configured on FastEthernet0/1 but will only

have effect when the interface is in a non-trunking mode

SW2(config-if)#int f0/1

SW2(config-if)#shut

SW2(config)#int f0/1

SW2(config-if)#no shut

（跳过监听，学习 直接FWD 状态）即能直接通信了！

 

 

SW3(config)#spanning-tree uplinkfast

SW3(config)#

*Mar 1 01:19:31.555: %SPANTREE_FAST-7-PORT_FWD_UPLINK: VLAN1 FastEthernet0/2 moved to Forwarding (UplinkFast).

 

SW3(config)#int f0/1

SW3(config-if)#shut

 

Interface Designated

Name Port ID Prio Cost Sts Cost Bridge ID Port ID

-------------------- ------- ---- ----- --- ----- -------------------- -------

FastEthernet0/2 128.3 128 3019 FWD 19 32768 cc04.1aa8.0000 128.3

FastEthernet0/3 128.4 128 3019 FWD 3038 49152 cc05.1aa8.0000 128.4

状态直接转换！

发现没有丢包！