BGP is a routing protocol that is used to exchange routing information between different autonomous systems (ASes) on the internet. An autonomous system is a network or group of networks that is under the same administrative control and uses a common routing protocol. By acquiring its own public IP prefixes and autonomous system number, a company can use BGP to advertise these prefixes to other ASes and establish its own internet connection. This would enable the company to have more control over its internet connection and potentially improve its connectivity.EIGRP (Enhanced Interior Gateway Routing Protocol) is a routing protocol used within a single autonomous system, so it would not be used to establish a connection to the internet. IPv6 is a version of the Internet Protocol (IP) used to identify devices on a network. It is not a routing protocol and would not be used to establish an internet connection.MPLS (Multi-Protocol Label Switching) is a networking technology that is used to route packets between different networks. It is not a routing protocol and would not be used to establish an internet connection.

The most likely cause of the issue where the fiber connection from a device to a switch is not working is that the TX/RX (transmit/receive) is reversed. When connecting fiber optic cables, it is important to ensure that the TX of one device is connected to the RX of the other device and vice versa. If the TX/RX is reversed, data cannot be transmitted successfully.
Reference:
CompTIA Network+ Certification Study Guide, Exam N10-007, Fourth Edition, Chapter 5: Network Operations, Objective 5.1: Given a scenario, use appropriate documentation and diagrams to manage the network.

OSPF uses a link state routing algorithm and falls into the group of interior routing protocols, operating within a single autonomous system (AS). OSPF is perhaps the most widely used interior gateway protocol (IGP) in large enterprise networks