Which three statements about the MST protocol (IEEE 802.1S) are true? (Choose three)
A.
To verify the MST configuration, the show pending command can be used in MST configuration mode.
B.
When RSTP and MSTP are configured; UplinkFast and BackboneFast must also be enabled.
C.
All switches in the same MST region must have the same VLAN-to-instance mapping, but different configuration revision numbers.
D.
All switches in an MST region, except distribution layer switches, should have their priority lowered from the default value 32768.
E.
An MST region is a group of MST switches that appear as a single virtual bridge to adjacent CST and MST regions.
F.
Enabling MST with the "spanning-tree mode mst" global configuration command also enables RSTP.
Explanation:
MST is built on the concept of mapping one or more VLANs to a single STP instance. Multiple instances of STP can be used (hence the name MST), with each instance supporting a different group of VLANs.
Each could be tuned to result in a different topology, so that Instance 1 would forward on the left uplink, while Instance 2 would forward on the right uplink. Therefore, VLAN A would be mapped to Instance 1,and VLAN B to Instance 2. To implement MST in a network, you need to determine the following:
1. The number of STP instances needed to support the desired topologies.
2. Whether to map a set of VLANs to each instance.