BGP - Why does iBGP require full mesh peering?

One of the requirements of internal BGP (iBGP) is that you must configure all iBGP routers within an AS to have full-mesh peerings. That means that every iBGP router in the AS must be configured as an iBGP peer of every other router in the AS! In this video I'll explain in further detail what this full-mesh peering prerequisite is, why iBGP requires it, and some of the scalability problems that arise from it. I will also touch upon the associated iBGP split horizon rule, as well as some additional features of iBGP, such as Route Reflectors and Confederations, that can be used to deal with scalability limitations. But those will be described in more detail in their own videos in the near future. If you want to find out more about the BGP routing protocol, or the method by which attributes are used to determine the best path, and other interesting features of the protocol, take a look at some of my other videos linked below (after the chapter list...) Chapter list: ============================================ 00:00 Introduction 00:15 iBGP Full Mesh 01:31 iBGP Split Horizon Rule 02:30 Why is a full mesh required? 03:27 Problems that May Arise 04:35 Solutions to the Scalability Problem 05:57 Route Reflectors 06:50 BGP Confederations 08:08 Summary Related links and videos: =============================================== Video: What is BGP? - https://youtu.be/fo9YxxKNO_g Video: eBGP vs iBGP - What's the difference? - https://youtu.be/3x7yztGSY-g Video: BGP attributes and determining the best path - https://youtu.be/ZZRsPcNllbU Video: BGP - Why does BGP require an IGP to function? - https://youtu.be/SN_TDZ2eDAA BGP Official Definition RFC 4271 - https://datatracker.ietf.org/doc/html/rfc4271 #ibgp #bgp #fullmesh #routingprotocol #autonomoussystems #router #lazarusagapidis