Why do you need a BGP router within the company?

Question

Border Gateway Protocol

I would be happy to explain why you might need your own BGP router in an enterprise, as far as I understand, the bgp protocol is used only at the AS level or it can be used, for example, in a private enterprise network

Answer 1

There is IBGP, there is EBGP, there are gray autonomies, there are white ones... Read about IBGP first.
The task of BGP is to drag (just drag, it is not in vain considered distance-vector) routing information, with its capabilities it can be done very flexibly (filtered, set priority). Well, and further, because of its flexibility (extensions), MPLS services (all sorts of VPNs) and EVPN (DPC IP factories) are launched on the basis of it. It is good practice to use it for any routing information generated outside of routers you personally manage. And in the end, since it uses TCP and many different states, it is very easy to monitor it (session up / down)

Answer 2

BGP is like a tomograph or a mining dump truck: if you don't know why you need it, you most likely don't need it)
In principle, it's true that initially BGP was built around the concept of an autonomous system (AS). However, it is worth remembering that there are AS ranges both public ("Internet") and internal, intended for use within an organization.
For the use of BGP within an organization, each manufacturer - Cisco, Juniper, Huawei, Alcatel-Lucent - has a separate line of courses "How to build an enterprise network, and why is BGP here")
For example, BGP can make life much easier if:
- you are building a network that unites several enterprises - each with its own IT department and a personal set of head cockroaches
- there are hundreds of VLANs on your network from dozens of sites, and you have to connect new and new nodes to them every day, randomly scattered over these sites (and here L3VPN / L2VPN / VPLS working via BGP will help you)