If you want to start exploring topics such as advanced routing, VLAN, OSPF, BGP, MPLS, IPsec,... here my book:
Index file in pdf format: https://www.zen.pn.it/images/book-routing-en.pdf
Paperback: https://www.amazon.com/Theory-laborator ... 1686046960
Kindle: https://www.amazon.com/dp/B07X5MHR1Y
Regards.
v.