问题
配置MSTP实现多生成树效果
配置A成为vlan 10 和 20 的主根，vlan 30 和 40 的次根
配置B成为vlan 30 和 40 的主根，vlan 10 和 20 的次根
查看配置信息
使用eNSP搭建实验环境：
步骤
实现此案例需要按照如下步骤进行。
[A]vlan batch 10 20 30 40
[A]int e0/0/2
[A-Ethernet0/0/2]port link-type trunk
[A-Ethernet0/0/2]port trunk allow-pass vlan all
[A]int e0/0/3
[A-Ethernet0/0/3]port link-type trunk
[A-Ethernet0/0/3]port trunk allow-pass vlan all
交换机B、C也同样配置。
[A]stp region-configuration
[A-mst-region]region-name tedu
[A-mst-region]instance 1 vlan 10 20
[A-mst-region]instance 2 vlan 30 40
[A-mst-region]active region-configuration
查看配置：
[A-mst-region]dis this
#
stp region-configuration
region-name tedu
instance 1 vlan 10 20
instance 2 vlan 30 40
active region-configuration
#
return
交换机B、C也同样配置。
3）配置主根与次根
[A]stp instance 1 priority 4096
[A]stp instance 2 priority 8192
[B]stp instance 2 priority 4096
[B]stp instance 1 priority 8192
4）验证
[A]dis stp instance 1
-------[MSTI 1 Global Info]-------
MSTI Bridge ID :4096.4c1f-cc87-1de7
MSTI RegRoot/IRPC :4096.4c1f-cc87-1de7 / 0
MSTI RootPortId :0.0
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :200000
TC received :5
TC count per hello :0
Time since last TC :0 days 0h:3m:6s
Number of TC :4
Last TC occurred :Ethernet0/0/2
----[Port2(Ethernet0/0/2)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc87-1de7 / 128.2
Port Times :RemHops 20
TC or TCN send :4
TC or TCN received :3
----[Port3(Ethernet0/0/3)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc87-1de7 / 128.3
Port Times :RemHops 20
TC or TCN send :2
TC or TCN received :2
[A]dis stp instance 2
-------[MSTI 2 Global Info]-------
MSTI Bridge ID :8192.4c1f-cc87-1de7
MSTI RegRoot/IRPC :4096.4c1f-cc0d-76bc / 200000
MSTI RootPortId :128.2
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :200000
TC received :4
TC count per hello :0
Time since last TC :0 days 0h:3m:49s
Number of TC :4
Last TC occurred :Ethernet0/0/2
----[Port2(Ethernet0/0/2)][FORWARDING]----
Port Role :Root Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc0d-76bc / 128.1
Port Times :RemHops 20
TC or TCN send :4
TC or TCN received :3
----[Port3(Ethernet0/0/3)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :8192.4c1f-cc87-1de7 / 128.3
Port Times :RemHops 19
TC or TCN send :2
TC or TCN received :1
[B]dis stp instance 1
-------[MSTI 1 Global Info]-------
MSTI Bridge ID :8192.4c1f-cc0d-76bc
MSTI RegRoot/IRPC :4096.4c1f-cc87-1de7 / 200000
MSTI RootPortId :128.1
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :0
TC received :4
TC count per hello :0
Time since last TC :0 days 0h:5m:26s
Number of TC :4
Last TC occurred :Ethernet0/0/3
----[Port1(Ethernet0/0/1)][FORWARDING]----
Port Role :Root Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc87-1de7 / 128.2
Port Times :RemHops 20
TC or TCN send :3
TC or TCN received :4
----[Port3(Ethernet0/0/3)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :8192.4c1f-cc0d-76bc / 128.3
Port Times :RemHops 19
TC or TCN send :1
TC or TCN received :0
[B]dis stp instance 2
-------[MSTI 2 Global Info]-------
MSTI Bridge ID :4096.4c1f-cc0d-76bc
MSTI RegRoot/IRPC :4096.4c1f-cc0d-76bc / 0
MSTI RootPortId :0.0
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :0
TC received :6
TC count per hello :0
Time since last TC :0 days 0h:6m:4s
Number of TC :5
Last TC occurred :Ethernet0/0/3
----[Port1(Ethernet0/0/1)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc0d-76bc / 128.1
Port Times :RemHops 20
TC or TCN send :3
TC or TCN received :4
----[Port3(Ethernet0/0/3)][FORWARDING]----
Port Role :Designated Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc0d-76bc / 128.3
Port Times :RemHops 20
TC or TCN send :2
TC or TCN received :2
[C]dis stp instance 1
-------[MSTI 1 Global Info]-------
MSTI Bridge ID :32768.4c1f-ccb8-32b8
MSTI RegRoot/IRPC :4096.4c1f-cc87-1de7 / 200000
MSTI RootPortId :128.1
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :200000
TC received :3
TC count per hello :0
Time since last TC :0 days 0h:6m:58s
Number of TC :3
Last TC occurred :Ethernet0/0/1
----[Port1(Ethernet0/0/1)][FORWARDING]----
Port Role :Root Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc87-1de7 / 128.3
Port Times :RemHops 20
TC or TCN send :2
TC or TCN received :2
----[Port2(Ethernet0/0/2)][DISCARDING]----
Port Role :Alternate Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :8192.4c1f-cc0d-76bc / 128.3
Port Times :RemHops 19
TC or TCN send :0
TC or TCN received :1
[C]dis stp instance 2
-------[MSTI 2 Global Info]-------
MSTI Bridge ID :32768.4c1f-ccb8-32b8
MSTI RegRoot/IRPC :4096.4c1f-cc0d-76bc / 200000
MSTI RootPortId :128.2
Master Bridge :32768.4c1f-cc0d-76bc
Cost to Master :200000
TC received :4
TC count per hello :0
Time since last TC :0 days 0h:7m:32s
Number of TC :4
Last TC occurred :Ethernet0/0/2
----[Port1(Ethernet0/0/1)][DISCARDING]----
Port Role :Alternate Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :8192.4c1f-cc87-1de7 / 128.3
Port Times :RemHops 19
TC or TCN send :1
TC or TCN received :2
----[Port2(Ethernet0/0/2)][FORWARDING]----
Port Role :Root Port
Port Priority :128
Port Cost(Dot1T ) :Config=auto / Active=200000
Designated Bridge/Port :4096.4c1f-cc0d-76bc / 128.3
Port Times :RemHops 20
TC or TCN send :2
TC or TCN received :2
查看负载均衡：
[A]dis stp bri
MSTID Port Role STP State Protection
0 Ethernet0/0/2 ROOT FORWARDING NONE
0 Ethernet0/0/3 DESI FORWARDING NONE
1 Ethernet0/0/2 DESI FORWARDING NONE
1 Ethernet0/0/3 DESI FORWARDING NONE
2 Ethernet0/0/2 ROOT FORWARDING NONE
2 Ethernet0/0/3 DESI FORWARDING NONE
[B]dis stp bri
MSTID Port Role STP State Protection
0 Ethernet0/0/1 DESI FORWARDING NONE
0 Ethernet0/0/3 DESI FORWARDING NONE
1 Ethernet0/0/1 ROOT FORWARDING NONE
1 Ethernet0/0/3 DESI FORWARDING NONE
2 Ethernet0/0/1 DESI FORWARDING NONE
2 Ethernet0/0/3 DESI FORWARDING NONE
[C]dis stp bri
MSTID Port Role STP State Protection
0 Ethernet0/0/1 ALTE DISCARDING NONE
0 Ethernet0/0/2 ROOT FORWARDING NONE
1 Ethernet0/0/1 ROOT FORWARDING NONE
1 Ethernet0/0/2 ALTE DISCARDING NONE
2 Ethernet0/0/1 ALTE DISCARDING NONE
2 Ethernet0/0/2 ROOT FORWARDING NONE
C上VLAN 10 20的流量通过Ethernet0/0/1口到A，VLAN 30 40的流量通过Ethernet0/0/2口到B，实现了链路的负载均衡。
