On this lesson page, https://networklessons.com/cisco/ccnp-route/bgp-attributes-and-path-selection/, you state that “On the Internet, it’s more important that you have granular control over how you forward your traffic and to which autonomous systems instead of just going for the shortest path based on a metric.” I would think it’s always most important to take the shortest path based on metric. Can you provide an example of why this isn’t always the case or further elaborate on that statement please?
Hello Mike
Rene states that
Internal Gateway Protocols (IGPs) such as OSPF, EIGRP and RIP use a metric that is composed of, for the most part, information that indicates the shortest path. OSFP and EIGRP incorporate more information to provide not only the shortest path, but the best path. And the best path is not always the shortest. OSPF and EIGRP incorporate bandwidth, delay, reliability, all of which are used to determine the best path.
Now BGP incorporates 11 attributes that are used to determine the best path. That is much more than RIP which uses one (hop count) or OSPF which uses bandwidth or even EIGRP which uses five or six depending on the version. (K1 through to K5 or K6).
Not only that, but each attribute is very specific and can be adjusted and readjusted and configured to do exactly what you like.
So the great advantage of BGP is the fact that there are so many options per attribute that can be adjusted and 11 attributes in total allowing you to adapt the methodology of routing to suit you. So in essence, because you have so much control over the nuances of the protocol, you are able to more appropriately route on the Internet, not based solely on shortest path, but truly on the absolute best path.
I hope this has been helpful!
Laz