• 10/13/2015
    8:00 AM
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BGP Fundamentals

Whats the big deal with Border Gateway Protocol? In this video, we explain what BGP is and how the routing protocol works.

When it comes to routing protocols, it doesn’t get much bigger than the Border Gateway Protocol (BGP). It’s the biggest one in the world because it’s the protocol that’s responsible for carrying all that wonderful traffic across the Internet.

BGP is most commonly used as an external routing protocol for large networks with multiple connections to the Internet. Companies or institutions that use BGP will have a unique autonomous system number that is exchanged with other BGP networks to create peering relationships with other autonomous systems. Through these partnerships, large networks and service providers provide BGP-controlled routes to, from, and through each other’s autonomous systems to give the Internet increased speed and efficiency, as well as a high level of redundancy.

One of the main benefits of BGP is that it’s a highly configurable routing protocol. Internally, BGP has a large set of criteria to determine the best route. That list of criteria can be altered by adjusting BGP attributes, creating prefix lists that affect what routes are advertised as well as access lists and routes maps that uniquely specify what routes are accepted and possibly set the cost of different available routes.

CBT Nuggets trainer and Cisco expert Jeremy Cioara explains BGP fundamentals in the video below:

Keep in mind, though, BGP is a “slow to converge” protocol. Routing changes on the Internet occur all the time. If BGP had to react to every change, it would flood the Internet with routing updates that could slow traffic all over the globe. So, BGP plays a waiting game to give routes time to settle down. Of course, this is not what you would want to occur inside your company's internal network. Your internal network needs to react to issues quickly to be effective. This is why BGP is seldom used as an internal routing protocol.

Understanding how BGP works, knowing its attributes, and understanding the route selection process enables you, as a network engineer, to have granular control over your Internet traffic -- and gives you the route redundancy needed to maximize your network availability.

To learn more about BGP, check out Jeremy Cioara’s “Cisco CCIP BGP 642-661” training course at CBT Nuggets (free trial required).


Nice Video!

Would like to thank CBNuggets for their video here!

I personally learnt a lot and I am sure most folks will too!

BGP is really-really important from a Networking perspective.

Its good to see some focus on this much needed Technology today.


Re: Nice Video!

Glad you liked the video Ashu001! I agree, I think it was a great overview of a key protocol.

Re: Nice Video!

It is great to learn about the overall network of a region especially, because it is difficult or impossible to carry out many vital tasks without the internet. A massive route leak can disrupt a regional network for many hours, latency can increase from 250ms to 500ms and packet loss can increase significantly, etc.

YouTube tries to provide information to its users about the possible causes of slow video load-time through a notification. However, there are so many other services that never try to increase a user's understanding of the network. It would be nice if a greater number of services (banks, Facebook and MOOCs) provided the necessary information.

Re: Nice Video!

I agree this is pretty impressive video, we all understand HTML, but BGP is something which can make a big good impact/ outage on internet if misbihaved, and interesting part is that most of the events that caused damage were misconfigurations.

Re: Nice Video!


Lets not forget the major fact that the reason why everyone understands HTML is the goal played by Youtube and various other Free channels online.

Its good to see similar channels also work to embrace basic Networking knowledge for all concerned(including BGP Fundamentals).


Re: Nice Video!

Good points, if BGP is the enabler that makes the network functional then, HTML is the language that communicates meaning and human thought across the network. And, anyone can use HTML through the help of tools such as, Markdown, etc. 

Re: Nice Video!


You are correct.

As is very clear from this blogpost and video,BGP is extremely fundamental to Development of robust networking infrastructure in major enterprises today.

It would be helpful if more networking Engineers paid focus on this key area going ahead.


Re: Nice Video!

"....and interesting part is that most of the events that caused damage were misconfigurations."

@virsingh211  Good point.  And now that we understand the enormous task, I can understand how this can happen.

Add issues of turnover and poor documentation and it is a wonder that it works as well as it does.

Re: Nice Video!

I still remember Verizon outage wherein they introduced some /24 routes for the larger block, but aggregation to these prefixes failed which resulted in the introduction of thousands of new /24 routes into the global routing table.  This caused the routing table to temporarily reach 515,000 prefixes and that caused issues for older Cisco routers which had 512,000 route limitation.

Re: Nice Video!


You have shared a great example of how the smallest issue neglected in Networks can cause catastrophic damage all across the network.

Its important that all consumers(even a major enterprise like Verizon is also a consumer for Networking services) keeps track of the various devices/Services they run in the Enterprise today.

The result of not doing so could very well push the same company out of Business.


Re: Nice Video!

Another interesting piece of reading from techcrunch,Everything is broken. Just ask any security engineer. Way back in 1998, the members of the hacker collective L0pht testified to Congress that they could take down the entire Internet in 30 minutes by abusing BGP, the Border Gateway Protocol, an obscure but critically important routing system. That was seventeen years ago and BGP is still vulnerable. Everything is terrible.


Re: Nice Video!


Fair enough words from Techcrunch here.

But rather than lamenting on the lack of effective protection I prefer focussing on why it has'nt happened yet.

Why has'nt BGP gotten patched all these years?

Who is responsible for maintainence of this Critical Protocol?

Are they badly fund-starved currently?If yes,can we crowd-fund an effective Patching Solution via Kickstarter,etc?

I have seen some really-really crucial protocols get funded via Crowd-funding today.Maybe its time to do the same with BGP as well?


Re: Nice Video!

@Ashu: You drafted well, but what is that you want to get patched in BGP. The current version of BGP we are using is version 4 codified in RFC 4271 since 2006. I am not sure if we any upgrade or ongoing progress in update for same.

Re: Nice Video!

Great Video! BGP is now more and more solicited. The slowest one but more robust in his design is now reqested into DC, SDN and done right!

Re: Nice Video!

The problem is not ony the design of this protocol but also, Networkers; we should focused on all his advantages. Let take BGP flowSpec, BGP based SDN, BGP based DC,... BGP done right there.

Re: Nice Video!

Now we need all to "repent" :)

We have many SDN vendors which are building their products on this protocol. But is it really SDN there ? :)

Re: Nice Video!


Fair points made by you here.

We need to cover not just basic BGP Protocols but also all Derivatives of BGP today.

In today's highly networked and interconnected world one really can't say where one small breach/vulnerability can cascade into a Fault of Global Dimensions.

This is why wherever BGP is used today;we need to make sure its patched and fully-functional taking into account all contingencies today.



Re: Nice Video!


Regarding your comments here-

YouTube tries to provide information to its users about the possible causes of slow video load-time through a notification. However, there are so many other services that never try to increase a user's understanding of the network. It would be nice if a greater number of services (banks, Facebook and MOOCs) provided the necessary information

I personally wondered whether the major reason why Other organizations are not so transparent about their network data is because most of them are not Consumer-facing Organizations.

Lets not forget that Google saw its origins (and continues to make) most of its Money from Small Consumers.They won't do anything to upset them on purpose.

It just makes no sense for them.

Other organizations not only don't spend half as much as Google does on Infrastructure but have different parameters when it comes to Servicing their clients.



Re: Nice Video!

It has become increasingly important for every organization to turn towards consumer orientations and away from product orientation. Unilever and Nestle are a few examples of companies that have managed to create a global presence through their focus on the consumer.

However, it is not easy for a company to become consumer orientated. Markets have to be researched in detail (logistics, consumer segmentation, culture and economic variables, etc.) and at its current state, not only are the road/infrastructure an important variable but, researching the network is equally important. Otherwise, a company might not be able to growth.  

Re: Nice Video!


Today we live in a world of (to quote Economists) Declining Demand.

In such a world any company which does not focus on Consumers will be finished in no time.

Lots and lots of companies(especially in Europe,China ,Japan and most of North America) are struggling with falling demand induced by a Glut of Supply of Labor and Commodities.

Why should a Customer chose one product over another in that case?

The only major Differentiator appears to be Customer Service.

The Customer is very much King today.

No Doubts about that.


Re: Nice Video!

@Ashu001, great point about "Declining Demand". Economists have been mentioning declining demand ever since, the price of energy (oil) dropped and it is right because, the correlation between energy consumption and economic activity is strong. Increased efficiency is another factor that is at play through hybrid and smart cars, etc., on the micro level and through services such as, Uber on the macro level.

It all translates into technology and the final price of a product or service that a business can offer to a customer through the use of technology.

Re: Nice Video!


Declining demand has a lot to do with the lack of Confidence of Consumers in their future Income Streams aka Jobs.

I was just reading the latest Challenger Report for US Job losses and would you believe it?Texas alone has lost over 100,000 jobs in the last one year(most of them in the Oil&Gas Sector).

If you remember closely from 2009 onwards,most Americans looked at Texas as a "Recession-Proof" State which would only see consistent growth in Jobs.

How that myth has shattered today!

The Global Oil&Gas industry has lost over 200,000 direct jobs in the last 18 months as Prices have collapsed.

And since most of those jobs were extremely high-paying its obviously going to translate into Declining Demand elsewhere and especially on Related Sectors Like Real Estate,Restaurants,Sand Companies,Steel Manufacturers,etc

Declining Demand directly means that Preserving Cash-Flows becomes super-critical (for all concerned Parties).

Lets also not forget that jobs in the Private Sector are'nt exactly coming today with Gold-Plated Pensions aka Public Sector Jobs.

Obviously,this means more folks will be looking to save and save aggressively.

This most definitely translates into the whole theme of Declining Demand which we were discussing here.


Re: Nice Video!

@Bian.Dean   This is protocol is invaluable in assessing WAN traffic flow.  As with the Looking Glass function, one can see the routes that another entity is using to transmit to you, if I understood correctly.  

So then it becomes an issue of tweeking the routes to optimize as best possible.  Wow, this is a huge function ( task).

Re: Nice Video!

@ClassC, agreed, it is invaluable to know the extent and to accurately know the exact cause of a bottleneck in a regional network. Oftentimes, news sources state that an undersea cable has sustained physical damage that is causing slowdown in regional data communication whereas, the real reason could be due to a massive route leak from a service provider.

Re: Nice Video!


A Massive route leak is something which just does'nt quite cut it in the same fashion with Network users as a Ship Anchor ripping apart a Submarine cable does ;Does it?

The simplest reason for that is the route leak tends to make one feel as if the Company has shortchanged infrastructure on the Network side.

However,that may not always be the case.


Re: Nice Video!

@Ashul001    I agree.  This was a great video on BGP.  It is a relief to finally have some understanding of how it works and what it is for.   It now makes sense that most network engineers might not understand it either - before this video.

Great learning resource.  Nice way to start the day.

love the micro nugget

hope you guys make more.

keep up the great work.

Big fan