What is Border Gateway Protocol (BGP)?

If you don’t know Border Gateway Protocol (BGP), you should. There’s a reason BGP is dubbed “the protocol that makes the internet work.” It does exactly that. This protocol controls the routing of traffic across the entire web — and is critical to your network infrastructure. BGP is mainly used by large networks for router configurations. But it’s also used by small home networks to access the internet. Even though it can be a complex protocol, understanding the basics of BGP gives you the skills to increase your network’s stability, security, and scalability.

What is Border Gateway Protocol (BGP)?

Border Gateway Protocol (BGP) is a routing protocol used to transfer data and information between different host gateways, the Internet, or autonomous systems. BGP is a Path Vector Protocol (PVP), which maintains paths to different hosts, networks, and gateway routers and determines the routing decision based on that. It does not use Interior Gateway Protocol (IGP) metrics for routing decisions but only decides the route based on path, network policies, and rule sets.

Sometimes, BGP is described as a reachability protocol rather than a routing protocol.

How does BGP work?

Each router maintains a routing table that controls how packets are directed. The BGP process on the router generates routing table information, which is based on the following factors:

• Incoming information from other routers.
• Information in the BGP routing information base (RIB), which is a data table stored on a server on the BGP router.

The RIB contains information both from directly connected external peers and internal peers. The RIB contains policies for what routes should be used and what information should be published, and it continually updates the routing table as changes occur.

Why is Border Gateway Protocol important?

BGP is an integral part of how the internet works today. Without it, there would be no way for different networks to communicate or share information about routes, making it impossible for data to be sent from one place to another efficiently and securely.

BGP enables the exchange of information between different networks and allows them to determine the best path for data to travel. It’s used by ISPs, large organizations, and cloud providers to connect their networks with each other and with the rest of the internet. BGP is also used to ensure traffic flows through the most efficient route possible, which helps reduce latency and improve performance.

Benefits of Border Gateway Protocol (BGP)

• Security: BGP is highly secure because it authenticates messages between routers using preconfigured passwords through which unauthorized traffic is filtered out.
• Scalability: BGP is more scalable because it manages a vast number of routes and networks present on the internet.
• Supports Multihoming: BGP allows multihoming means an organization can connect to multiple networks simultaneously.
• Calculate the Best Path: As we know data packets travel across the internet from source to destination every system in between the source and destination has to decide where the data packet should go next
• TCP/IP Model: BGP is based on the TCP/IP model and it is used to control the network layer by using transport layer protocol.

Types of Border Gateway Protocol

• External BGP: It is used to interchange routing information between the routers in different autonomous systems, it is also known as eBGP(External Border Gateway Protocol). The below image shows how eBGP interchange routing information.
  eBGP
• Internal BGP: It is used to interchange routing information between the routers in the same autonomous system, it is also known as iBGP(Internal Border Gateway Protocol). Internal routers also ensure consistency among routers for sharing routing information. The below image shows how iBGP interchange routing information.

When is BGP used?

The Border Gateway Protocol is used as external BGP and as internal BGP. Being the only external gateway protocol on the internet, it’s used for routing and managing data exchange between and within autonomous systems. By making decisions based on policies and rules defined by network administrators, it guarantees better network stability. This is possible, for example, by allowing routers to flexibly adapt in case of failures and to choose other logical routing paths available via BGP for exchanging packets. In addition, BGP updates enable routers to add new ones to the default routing table in use.

Conclusion

BGP is a powerful, versatile protocol that enables organizations to build reliable computer networks by exchanging routing information between autonomous systems. BGP offers features such as path selection and route filtering which are essential in providing the best possible network connectivity.

However, BGP has vulnerabilities that must be addressed to maintain secure routing operations. Also, BGP is not the only routing protocol available and organizations may want to consider using other protocols such as OSPF or EIGRP.

Please note that while this overview of BGP is a good introduction, it is far from being exhaustive. If you are ever assigned to manage a BGP router, take some time to read through the RFCs associated with it.