It is only required on Switch B. Switch B will tag incoming frames with another 801.q tag on ingress. On egress, it will remove that tag. Therefore, Switch A will perceive that it is simply talking with another Switch over a dot1q trunk.
Hope that helps - pls do rate the post if it does.
We are pleased to announce availability of Beta software for 16.6.3. 16.6.3 will be the second rebuild on the 16.6 release train targeted towards Catalyst 9500/9400/9300/3850/3650 switching platforms. We are looking for early feedback from custome...