What is BGP? - Border Gateway Protocol

What is BGP?

Border Gateway Protocol (BGP) is used to Exchange routing information for the internet and is the protocol used between ISP which are different ASes.

Border Gateway Protocol is the protocol that makes the Internet work. Networks or autonomous systems that need to interact with each other do so through peering, which is made possible with BGP.

BGP - Border Gateway Protocol

Border Gateway Protocol (BGP) is the postal service of the Internet. When someone drops a letter into a mailbox, the postal service processes that piece of mail and chooses a fast, efficient route to deliver that letter to its recipient. Similarly, when someone submits data across the Internet, BGP is responsible for looking at all of the available paths that data could travel and picking the best route, which usually means hopping between autonomous systems.


BGP is the protocol that makes the Internet work. It does this by enabling data routing on the Internet. When a user in Singapore loads a website with origin servers in Argentina, BGP is the protocol that enables that communication to happen quickly and efficiently.

What is an autonomous system?

The Internet is a network of networks; it’s broken up into hundreds of thousands of smaller networks known as autonomous systems (AS). Each of these networks is essentially a large pool of routers run by a single organization.

Characteristics of Border Gateway Protocol (BGP):

• Inter-Autonomous System Configuration:
  
  
• The main role of BGP is to provide communication between two autonomous systems.
  
  
• BGP supports Next-Hop Paradigm.
  
  
• Coordination among multiple BGP speakers within the AS (Autonomous System).
  
  
• Path Information: BGP advertisement also include path information, along with the reachable destination and next destination pair.
  
  
• Policy Support: BGP can implement policies that can be configured by the administrator. Between the routes that are known within the AS and that which are known from outside the AS.
  

Runs Over TCP.
BGP conserve network Bandwidth.
BGP supports CIDR.
BGP also supports Security.

Functionality of Border Gateway Protocol (BGP):

BGP peers performs basic three functions, which are given below.

The first function consist of initial peer acquisition and authentication. Both the peers established a TCP connection and perform message exchange that guarantees both sides have agreed to communicate.

The second function mainly focus on sending of negative or positive reach-ability information.

The third function verifies that the peers and the network connection between them are functioning correctly.