Dear friend,
You can download the learning materials from the post below:
https://forum.huawei.com/enterprise/en/hcia-transmission-class-notes-waiting-for-you-to-get-it/thread/745163-875.
Learn more from the related videos and key knowledge points from this topic:
https://forum.huawei.com/enterprise/en/forum.php?mod=collection&action=view&ctid=523.
In your study, if you do not understand something, your are welcome to ask for help on our forum. I'll provide you with an answer in time.
Good luck!