Introduction: What is BGP?
The data is transferred at a very high speed. How does that happen when the servers are located thousands of miles away? A route is created in the internet which allows the information to flow quickly from one end (the user) to the other (the server). A route announced in BGP consists of the IPV4 or IPV6 address block. BGP plays a major role in this process. Let's dive right into our article and look at what this thingamajig is all about.
The internet is a collection of different networks. You might remember learning about LAN, MAN, and WAN back in school. A Local Area Network is a network of closely-placed computers connected to one another. A MAN (Metropolitan Area Network) is a collection of different LANs in a region. This means that a bigger network i.e. MAN is an amalgamation of different smaller networks i.e. LANs.
Similarly, the internet is like a colossal collection of smaller networks. These smaller networks are known as AS’s or Autonomous Systems. They are like the cells of the net in that they are the ‘building blocks’ with which it is made up. When information has to be relayed from one point to the other via the internet, the bundle of data is carried along different AS’s until it reaches the destination. The bundle is handed by one AS to the next and like a sack of potatoes, it is passed on from one end to the other.
Since there are tens of thousands of autonomous systems in the internet, there are a lot of different routes that the packet of information can go through. However, there will be one ideal course that will be the shortest and the best suited for relaying the data. The BGP (Border Gateway Protocol) is responsible for determining this best pathway for the particular set of information.
What is the use of BGP?
BGP allows the different autonomous systems to share the routing instructions and details among themselves so that the transfer channel is established. It’s like when you are going from Japan to Canada, you have to land at some airports along the way and you may even have to switch planes since the two countries are so far apart. The journey is planned out with different stops and breaks. The autonomous systems are like airports scattered along the route and the data is like the plane, going from one stop to the other and completing the trip.
Now if your travel agency was to plan a route that takes you first to Russia, then to South Africa, then to the Middle East, then to a little detour around India, and then across Europe to Canada, you wouldn't call that an ideal route. An ideal route would be one that goes straight to Canuckistan making just the essential stops along the way. Applying this analogy, we can simply say that BGP is like a travel agency that has to coordinate the whole trip by making different airlines and airports communicate with one another and agree on a route.
Let’s take a look at a little graphic here to see the function that BGP serves to fulfill.
Suppose this is the internet…with just these many autonomous systems. Our data has to be transferred from A to F. The red arrow shows the best route. The other two are feasible, but they aren't ideal. Now, this diagram is really simple because you can easily see that the red route requires the data to jump only thrice viz. from A to L, L to M, and M to F. But imagine if instead of just thirteen autonomous systems, there were a hundred thousand. That would be a far more complex job, and that is what BGP is for.
External and Internal BGP
This is another concept that requires a little bit of elucidation. There are basically two types of BGP. The one we have been discussing above is called the ‘External BGP’.
When we are looking at the working of BGP where autonomous systems are the primary components, we call it external BGP. External BGP is the one where different autonomous systems carry along data from one point to another by establishing a route between themselves.
Just like the internet, each AS (autonomous system) is also made up of smaller networks. It’s sort of like a ‘box in a box’ thing. The communication and exchange of information that happens inside an AS are called internal BGP.
Instead of getting all muddled, we can say that when BGP is employed for planning a route between autonomous systems, it is called external. When BGP is employed by an AS for exchanging information within itself, it’s called internal.
If we want to use another example here, we can simply draw a comparison with travel. When a trip is planned between different countries via air or sea, it is like external BGP because it is international. However, when a trip is planned using the same technique within a country i.e. interprovincial or intercity, it is like internal BGP. Both BGP and DNS systems allow an organization to control how traffic reaches its systems.
Here, check out this close-up shot of the graphic we used above. This should clear it up a bit more.
Conclusion
There you have it, folks. In this article, we looked at the Border Gateway Protocol and the function it performs in the working of the internet. To recap, BGP enables different autonomous systems to share routing information with one another and create a pathway for the transferring of data. BGP rerouting can mitigate direct-to-origin DDoS attacks. And It is done by screening all incoming network traffic before it reaches out its target.
BGP is the system that makes it possible for data to be transmitted over the internet quickly. When a person from one end of the world wants to open up a website operated by someone at the other end, it is the border gateway protocol that allows the formation of a channel for the data transfer.
