在eNSP中新建如下拓扑

步骤：
1.关闭连接主机的端口的生成树协议: sw1,sw2,sw3
int e0/0/3
stp disable
int e0/0/4
stp disable
2.创建vlan : sw1,sw2,sw3
vlan batch 10 20
3.把端口加入vlan:sw1,sw2,sw3
int e0/0/3
port link-type access
port default vlan 10
int e0/0/4
port link-type access
port default vlan 20
4.设置trunk端口:sw1,sw2,sw3
port-group 1
group-member e0/0/1 e0/0/2
port link-type trunk
port trunk allow-pass vlan all
5.创建stp域和创建两条路:sw1,sw2,sw3
stp region-configuration
region-name ABC
instance 1 vlan 10
instance 2 vlan 20
active region-configuration
6.设置每条路的拓扑，为每条路确定根网桥
[sw2]stp instance 1 priority 4096
[sw3]stp instance 2 priority 4096
7.分别测试vlan10和vlan20中各主机通联