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What Is The BGP Protocol, And What Is It For

BGP is one of the most important protocols for the functioning of the Internet: without it, data packets would not know where to go. Hardly anyone knows what it is. Few know that it exists. Still, billions of people depend on it for their daily Internet activities: we are talking about the Border Gateway Protocol (BGP), one of the many protocols regulating the global network’s functioning. But also one of the most important, since the Internet has reached mammoth dimensions.

BGP is the classic example of a technology that must always work silently but efficiently and that, when it doesn’t work, causes serious trouble. An example of how serious these troubles can be when the BGP protocol has a problem was Facebook’s total downtime on October 4, 2021, which lasted over six hours. At the origin of the complete “disappearance” of Facebook from the Web and apps worldwide, there was a problem with the Border Gateway Protocol.

Border Gateway Protocol: What It Is

The Border Gateway Protocol is, as the name implies, a protocol. That is, a set of rules that the hardware infrastructure on which the Internet is based must follow to function correctly. Thanks to the protocols, all the machines can speak the same language, understand each other, and complete the tasks they remain in 24 hours a day. Specifically, the BGP protocol has a role that many describe as an Internet post office.

BGP is the protocol that indicates which path they must follow to incoming data requests to reach the server where the data of interest are located. It may not be the shortest path in terms of physical distance between client and server, but in theory, it is the best because BGP routes requests in an optimized way, i.e., minimizing waiting times. In this sense, the path followed to reach a specific datum can always be different based on the network situation and the Internet traffic present at that moment.

For this reason, if BGP has a problem, it is not possible to determine where the data must pass to go from point A to point B. Of BGP protocols there are two: the “external” BGP (eBGP) and the “internal” one (iBGP). The BGP protocol is the one used within the so-called “autonomous systems” ; the eBGP one is used to connect the autonomous systems and, in practice, helps keep the entire Internet network up and running.

By autonomous systems, we mean complex structures, such as Internet Service Providers (ISPs), a sizable online organization, and, finally, a large company that offers online services such as Facebook. In practice, these are large “islands” within the sea magnum of the Internet, within which data circulates following the rules of the BGP protocol. Instead, the BGP protocol is used when data has to be circulated from one island to another.


Many, at this point, will be thinking of another famous Internet protocol: DNS, Domain Name System. These are two very different protocols with equally different roles. If BGP is the post office, DNS is the directory: it is used to translate the names of websites into their respective IP addresses. 

However, BGP and DNS work together: when a user wants to access a site and enters his web address in the browser bar, the DNS server of the user’s ISP translates the name of the site in the corresponding IP address, but it is then the BGP protocol that decides which “tour” the data must make to arrive from the requested site to the user’s computer (or smartphone, or another connected device). And vice versa. However, BGP uses another famous Internet protocol: TCP, Transmission Control Protocol, to transfer messages with the “route” of the data. And this is yet another confirmation of how complex the infrastructure on which the Internet is based today is.

Geopolitics And Security Of The BGP

Although all this may sound very theoretical, in reality, the BGP protocol has efficient effects on the functioning of the Internet: it decides which routers pass data through which computers and servers are involved in packet exchanges. For this reason, BGP is also managed based on geopolitical and security needs. To give an example: if State A and State B are at war, or in any case in bad relations, it is clear that each of them does not want the communication data between their citizens (or, worse still, between their officials) to pass through routers physically located in the opposing State. Not even in enemy-friendly states. 

This is because there is a substantial security risk in relying on BGP: the so-called “BGP hijacking,” that is, “BGP hijacking,” consisting of a cyber attack aimed at artificially modifying the path made by the data by intervening precisely on the instructions provided. From the BGP. By hijacking data packets and passing them through a router under their control, attackers can copy that data and attempt to decrypt it to read its contents.



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