Which origin code is preferred in BGP path selection?

In the BGP (Border Gateway Protocol) path selection process, the origin code "IGP" (Interior Gateway Protocol) is preferred over the others. This is because IGP indicates that the route was learned from within the autonomous system using an internal routing protocol such as OSPF or EIGRP. Routes with an IGP origin are deemed more reliable and preferred because they are considered to have originated from a well-defined interior routing mechanism that provides better control and stability.

In contrast, an EGP (Exterior Gateway Protocol) origin indicates that the route was learned from another autonomous system, which is less reliable than routes learned through an IGP. The "Incomplete" origin signifies that the route information was sourced from an unknown or incomplete mechanism, making it the least trustworthy.

The BGP selection process places importance on route reliability and stability, which is why IGP is at the top of the origin attribute preferences. Being aware of this preference helps network engineers make informed decisions regarding BGP route selection in complex networks.