What is BGP (Border Gateway Protocol)? | Its Role in Network Routing

BGP, or Border Gateway Protocol, helps networks talk to each other. It’s like a language for exchanging directions between different parts of the Internet. Big internet companies have their ways of working.

Thus, using BGP is essential to make sure they can all talk to each other. It makes data flow smoothly between these different parts of the Internet, making sure everything works efficiently.

What is BGP (Border Gateway Protocol) in Networking?

BGP helps internet providers share directions between their systems. Each system that uses BGP talks to other systems to figure out the best way to send data. In short, it makes sure data can move between different parts of the Internet. That’s why network admins often use it.

Setting up BGP is simple. First, figure out where the Autonomous Systems (AS) are. Then, manage the traffic between networks. Lastly, install BGP to make it work well.

Internal connections within AS units are iBGP, i.e., Internal. External sessions are External, i.e., eBGP. Thus, iBGP handles connections within an AS, while eBGP manages connections outside it. It’s like having a different way to talk, depending on who you’re talking to. It is an External Gateway Protocol. In short, eBGP picks the best paths and shares directions between different networks.

Big internet companies use this protocol. That’s why It’s an essential way for networks to find the best paths for data.

BGP4 helps with CIDR and path aggregation. Unlike other routing protocols like IGP, RIP, OSPF, and EIGRP, it doesn’t care about things like how many hops, bandwidth, or how fast data moves. Unlike other protocols, it decides how data travels. It looks at network rules and uses different routing features to make those decisions.

RFC 1105 defined the first version of BGP in 1989 as a replacement for EGP. RFC 1163 defined the second version in 1990, followed by RFC 1267, defining the third version in 1991. Finally, RFC 1771 and RFC 4271 explain version 4 of this protocol, which includes support for CIDR.

Features of BGP Protocol

The main features of the border gateway protocol are;

• It’s a way to figure out the best path for data to travel.
• It supports different ways of organizing IP addresses, like VLSM and CIDR, and grouping routes together.
• It sends out all the route information when it starts talking to another system.
• It establishes and maintains peer-to-peer connections over TCP port 179.
• Whenever there’s a change in the network, it tells everyone else about it.
• It uses attributes to decide which path data should take, giving lots of detail.
• It’s flexible because it can change how traffic moves around the network.
• It has its list of routes but can also ask other systems for help.
• It can control how data flows by using those attributes.
• This protocol pays attention to specific parts of the network, finding the best path for each one.
• It shares updates about routes with others, including only the necessary info.
• This protocol makes sure data gets where it needs to go reliably by keeping everyone’s route info up to date.

What is AS (Autonomous System)?

Each AS works on its own and has its own set of rules for how data should travel. On the other hand, it helps these ASs talk to each other by connecting them through this protocol.

ASs don’t know what’s happening inside other ISPs’ networks. They see them as one big area that’s managed together. In short, it makes it easier to share routing info and keep routing tables organized.

Border Protocol makes a list of all the ASs on the Internet. Routing info goes through these systems. These organizations:

• IANA (Internet Assigned Numbers Authority)
• RIR (Regional Internet Registries)

How Does BGP Work?

Border Gateway Protocol uses port 179 and works over TCP to set up connections between different ASs. Primarily it makes sure data travels safely, especially when routes between ASs change. Also, it keeps the inner workings of the network private.

Every AS uses an IGP to figure out the best paths for links. Putting limits on routes can make it harder to find the quickest way to each place. But it’s essential to think about certain limits for getting around efficiently. After all, it uses an algorithm a bit like a road map to pick routes with the fewest ASs to go through.

BGP routing tables keep track of the best ways to reach certain networks. To get a specific address, you have to follow paths made up of autonomous system numbers. So, these routes lead you to the correct address by going through different systems.

Keeping track of all routes helps to find and stop loops. Loops happen when packets keep going through the same AS over and over. This way, it makes sure data travels efficiently without getting stuck in a loop.

What are The Differences Between iBGP and eBGP?

iBGP and eBGP are different types of BGP in networking. iBGP stands for Internal BGP, while eBGP stands for External BGP. The main difference is how they handle connections between AS.

In simple terms, Internal deals with routing inside one AS, while External handles routing between different ASes. So, it spreads routes within the AS, while eBGP shares routes outside of it.

When a router gets a route from an external peer, it sends it to other routers using the same AS using iBGP. This way, all routers in the AS know the route and can forward packets correctly. But if a router gets a route from an iBGP peer, it doesn’t pass it along to other peers. Instead, the router decides on the best path to the destination by itself using its table.

In eBGP, the Next Hop attribute becomes the peer’s IP address, which helps with forwarding packets. But in the internal one, the original Next Hop attribute stays the same. In short, Routers use their tables to figure out where to send packets next.

In short, both types are crucial in BGP routing. The internal part deals with the way inside an AS, while the external part takes care of the way between ASes. As a result, understanding the differences between them helps admins build better LANs.

Message Types

BGP uses different kinds of messages to tell others about new routing info.

Open

The protocol uses this message type to start talking after a set TCP connection.

Update

This message type is super essential for BGP. Whenever a router finds a better way to reach a place, it tells everyone by announcing new prefixes.

Notification

It uses this message type to report errors and log out of a session.

Keepalive

These messages keep track of the start time of sessions and ensure they are running correctly.

Types of Situations for Border Gateway Protocol

The router uses different statuses to show how it’s working. So, it goes through these states while setting up a session.

Idle

The Idle state is where the router starts. BGP mainly uses this when adding a neighbor or setting up an interface. It’s also the start of setting up a session.

Connect

This happens when the router is waiting to finish its TCP session. After that, it lets the router listen for new incoming TCP sessions.

Active

An active state refers to the waiting time for a TCP session.

OpenSet

The OpenSet status reports the delivery time of the open message. However, the router is still waiting for a response from the device it is trying to connect to.

OpenConfirm

OpenConfirm means the router got the Open message it sent before. But it’s still waiting for a KeepAlive message.

Established

In the Established state, the router starts sending messages. It sends Update, Information, and KeepAlive messages after getting the first KeepAlive.

Frequently Asked Questions (FAQ) About BGP

Conclusion

In conclusion, BGP is super important because it helps different systems talk to each other smoothly. It’s unique because it works differently from other ways of routing. Plus, it keeps getting better with new versions and updates.

With more people needing fast data, it becomes more critical. It’s good at handling complicated routing rules, which admins like. For this reason, we often prefer it for large networks that need to grow.

As this protocol gets better, it becomes super essential for networking. As a result, it’ll keep being a big deal in how the Internet works.