Video presentation: Computer Networks and the Internet.
5.4 The Border Gateway Protocol (BGP). BGP basics, BGP and path advertisement, iBGP and eBGP and forwarding tables.

Computer networks class.
Jim Kurose
Textbook reading: Section 5.4, Computer Networking: a TopDown Approach (8th edition), J.F. Kurose, K.W. Ross, Pearson, 2020.
See http://gaia.cs.umass.edu/kurose_ross for more open student resources.