What is BGP?
How does it work? Why is it used?
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BGP (Border Gateway Protocol) is a routing protocol that is used to exchange routing information between different networks on the internet. When a user tries to access a website in a browser, the request first goes to the user's local network, which then forwards it to the network's or ISP's border router. From there, BGP is used by the routers to determine the best path for the request to travel through different networks to reach the destination network where the website is hosted.
On the internet, various networks are called Autonomous Systems (AS). These ASes belong to various ISPs or Network Providers or Companies like Verizon, Xfinity, Google, Facebook, etc. Their interconnection makes up the internet around the world. These ASes have numerous routers at the borders of their network, which spans the globe.
The border router of the ISP sends the request to another border router of an AS, and it goes forward and reaches the destination using the smallest path. What happens is that each router uses BGP to figure out the smallest path to the destination and sends the request accordingly to the next router.
Eventually, the request reaches the network that is hosting the website, and BGP is used to route the request to the specific server that is hosting the website. BGP is also used to route the response back to the user's browser, following the same path in reverse.
In summary, BGP plays a critical role in determining the best path for network traffic to travel between different networks on the internet, including when a user tries to access a website in a browser.
