In the network connection as shown in the figure, SWA/SWB/SWC are in the same MSTP domain and configure the same domain configuration

In the network connection as shown in the figure, SWA/SWB/SWC are in the same MSTP domain and configure the same domain configuration

stp region-configuration

region-name h3c

instance 1 vlan 10

instance 2 vlan 20

instance 2 vlan 30

active region-configuration

The ports of the three interconnected links are all Access and belong to the VLAN as shown in the figure. The three switches respectively create the VLAN virtual interface corresponding to the Access link and run OSPF on the virtual interface. The IP address of the VLAN virtual interface is assigned as follows:

SWA: vlan-interface 10 (192.168.10.1); vlan-interface 30 (192.168.30.1)

SWB: vlan-interface 10 (192.168.10.2); vlan-interface 20 (192.168.20.1)

SWC: vlan-interface 20 (192.168.20.2); vlan-interface 30 (192.168.30.2)

When the interconnection ports are all UP and the STP and OSPF calculations are completed, the following descriptions about network connectivity are correct:
A . Three switches can establish OSPF neighbor relationships in pairs
B . Two of the three switches cannot establish OSPF neighbor relationships
C . All interconnection addresses of the three switches are mutually reachable
D . Among the 6 interconnected addresses, at least two interconnected addresses are mutually unreachable