What is BGP (for Beginners)

[bingosquirrrell1]

Can someone please explain what BGP is (for beginners).

[Joseph W. Doherty]

What kind of beginner?

For example, new to networking, new to routing, new to BGP?

This question, and your other posted question, on route tables, are very openned ended.

[bingosquirrrell1]

Hello,

So by beginner I mean I have almost zero experience with networking, routing, BG, and route tables.

The most I usually do is random google searches, but on these threads I'm wanting to go more in depth.

With this and my other post, I'm looking to get an answer that'll help me understand what these terms mean.

[Joseph W. Doherty]

Okay, understand.

If you're learning networking, it's often requires a broad knowledge for it to make sense.

BGP, Border Gateway Protocol, is an external (between ASs [Autonomous System]) dynamic routing protocol.

BGP is used for Internet routing.  It's not the only routing protocol used to support the Internet nor is it only used for Internet routing.

Likely you'll find you don't want to delve into BGP until you've a much better understanding of networking.  Consider there are books just about BGP.  (Actually, the protocol, itself, isn't too hard to understand, but how to effectively use BGP can be difficult to learn.  Real world ISP network engineers, by Cisco certification levels, are usually professional or expert levels.)

[Richard Burts]

So here is my attempt at explanation for a very new beginner. 

We frequently want to send data from some source to some destination. To determine what path to use to get from the source to the destination we use routing. routing may be static or dynamic. In static routing we manually enter information specifying the path to use. In dynamic routing we use some routing protocol to learn the path and to react if something changes that makes this path worse or makes some other path better. 

In dynamic routing we distinguish between routing protocols that operate within an organization/entity (think routing for your company - if you are employed or think routing for your school if you are a student) or protocols that operate between organizations/entities (think Internet). Routing protocols that operate within an organization/entity we refer to as Interior protocols and examples of this include RIP, OSPF, EIGRP. Routing protocols that operate between organizations we refer to as Exterior protocols and the main example of this is BGP.

I hope this is helpful. If you need additional information please post additional follow up questions.

[Leo Laohoo]

Try THIS.

[feh.ramos]

What is BGP?

BGP (Border Gateway Protocol) is a protocol used to exchange routing information between different networks on the internet. It helps routers determine the best path to send data across the vast and interconnected network of the internet.

Why is BGP important?

• Global Connectivity: BGP is the protocol that makes the internet work. It connects different Autonomous Systems (AS), which are large networks managed by internet service providers (ISPs), large organizations, or universities.
• Path Selection: BGP decides the best path for data to travel from one point to another, ensuring data takes the most efficient route.
• Scalability: BGP can handle a large number of routes, which is essential for the ever-growing size of the internet.

How does BGP work?

1. AS (Autonomous Systems): The internet is divided into many ASes. Each AS is a network managed by a single organization and has a unique AS number.
2. Neighbors/Peers: Routers in different ASes use BGP to communicate with each other. These routers are called BGP neighbors or peers.
3. Route Advertisement: Routers share information about the networks they can reach. This information includes the paths to various IP addresses.
4. Best Path Selection: BGP uses several factors (like the number of ASes a path traverses) to decide the best path for data to travel.

Key Concepts

• Autonomous System (AS): A collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet.
• BGP Router: A router that runs BGP to exchange routing information with BGP routers in other ASes.
• Peers: Routers in different ASes that exchange routing information using BGP.
• BGP Table: A table in the router that contains paths to different networks, received from its peers.

Basic BGP Configuration Example

Here's a basic example of configuring BGP on two routers that are in different ASes:

Router 1 (AS 100):

en

conf t

hostname Router1

int g0/0 ip address 192.168.1.1 255.255.255.0

no shut

exit

router bgp 100

neighbor 192.168.1.2

remote-as 200

exit

wr

Router 2 (AS 200):

en

conf t

hostname Router2

int g0/0 ip address 192.168.1.2 255.255.255.0

no shut

exit

router bgp 200

neighbor 192.168.1.1

remote-as 100

exit

wr

Verifying BGP Configuration

To verify the BGP configuration and check if the routers have established a BGP connection, use the following commands:

• Show BGP neighbors:
  plaintext

  Copiar código

  show ip bgp summary
• Show BGP routing table:
  plaintext

  Copiar código

  show ip bgp

Summary

BGP is a critical protocol for routing data across the internet. It connects large networks, helps select the best path for data, and ensures global connectivity. Understanding BGP is essential for anyone interested in network engineering and internet infrastructure.

[M02@rt37]

Hello @bingosquirrrell1 

BGP, or Border Gateway Protocol, is the protocol used to exchange routing information between different networks on the Internet, often referred to as autonomous systems (AS).

It's essentially the "postal service" of the Internet, determining the best paths for data to travel across multiple networks to reach its destination. BGP ensures that data can find its way from one corner of the world to another by choosing the most efficient and reliable routes, taking into account network policies and the current state of the Internet.

Unlike other routing protocols that operate within a single network, BGP handles the complex task of connecting large, disparate networks, making it a crucial component for the global Internet infrastructure.

[bigevilbeard]

@bingosquirrrell1  Imagine a big pond with lots of little islands. Each island is like a different network of computers. BGP (Border Gateway Protocol) is like a group of ducks who are really good at swimming between the islands.

These ducks (BGP) chat with each other and share information about which paths are open, which are blocked by rocks or weeds, and which have the strongest currents. They use this information to create a map of the pond, showing the best way to swim from any one island to any other. When a duck wants to swim from one island to another, they ask BGP for directions. BGP looks at their map and tells them the quickest and safest route to take. This helps all the ducks get where they want to go quickly and easily, without getting lost or swimming into any trouble.

In the same way, BGP helps computers find the best way to send information to each other across different networks. This makes the internet faster and more reliable for everyone.

Hope this helps.