Refer to the exhibit.
MSTP is enabled on the switches shown in the exhibit.
Which additional step should the network administrator take to support load sharing of traffic on different switch-to-switch links?
A. Configure different spanning tree port priorities for different instances on each access layer switch.
B. Assign different spanning tree port costs to different instances on each access layer switch.
C. Ensure that half of the switches use config revision 1 and half of the switches use config revision 2.
D. Create an identical VLAN-to-instance mapping on each switch, in which some VLANs are in each instance.
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From the guide:
To implement the most effective load sharing, you need a separate instance for each distribution/aggregation switch (Core-1 and Core-2). Then each of these switches can act as root in one instance and uplinks to that switch can be active in that instance. Therefore, in the first scenario, two instances (in addition to instance 0) work.
The number of VLANs does not affect the number of instances that you need. You can assign half of the VLANs to one instance and half to the other. Or you might take a more nuanced approach to load-balancing. For example, you can look at the typical traffic load for each VLAN and combine the VLANs such that each instance has about half the load (but not necessarily half the VLAN IDs).
You also can choose not to load-balance traffic evenly. For example, maybe you want to reserve a path for a critical VLAN, but you do not care that other VLANs have to share bandwidth. You would then give the critical VLAN its own instance and assign other VLANs to the other instance.
I believe the answer is D, though that answer is particularly weird.
for me is D
I bet B
Different priorities help in case of several connections between two switches, but not with access switch having uplinks to two distribution switches – A is wrong.
Different revision numbers will split the domain. It doesn’t help with load sharing (rather the opposite) – C is wrong.
Answer D provides a necessary requirement for load sharing with MSTP, but is not enough to get the effect. I.e. the described mapping is necessary, but is not enough to get the load sharing effect.
Sorry – D is OK.
I didn’t notice root bridge assignments at the picture.
Isn’t the answer should be D?