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Implementing Cisco IP Routing (642-902 ROUTE) Tutorials
BGP / Overview of BGP pt. 1
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Subtitles of the Movie (Implementing Cisco IP Routing (642-902 ROUTE) / BGP / Overview of BGP pt. 1)
Welcome into BGP or the Border Gateway Protocol. Now jumping from IGP is like OSPF and EIGRP into BGP, it's quite the shift and if you don't use a clutch, you'll blow your little mind sometimes. However at least at the CCNP level, you just have to know the basics about BGP and, and so we'll jump right in here and, and we'll talk a little bit about it and then you know, I'm famous for putting everything in a lab, so we'll stick it in a lab and build out a whole BGP network. So as I've mentioned, BGP is the Border Gateway Protocol. It is the routing protocol of the Internet. If you deal with large Internet providers like Layer 3 or Deltacom, UUNET, AT and T. You deal with the big providers, you're probably going to have to know how to use BGP in your environment. That's because all of these big ISPs and all major ISPs use BGP at some point even if they're just using it to connect to other ISPs. And even if you work for a smaller, like a regional ISP, you'll still have to connect to your provider somehow. Now BGP is considered a Path Vector Protocol, it's very similar to a Distance Vector Protocol but it is much more flexible than your average Distance Vector Protocol, which is, well which is RIP, I, I don't know of any other Distance Vector Protocols of the top of my head. And since it is very similar to a Distance Vector Protocol, it acts exactly like RIP unless you tune it properly. Obviously RIP is, is not the best protocol on the planet, it's fallen out of favor, but for several years, even by the time I recorded this video and by the time you see it, it's going to be further in the past. I mean, no one uses RIP, even the, the little wireless routers you get at Best Buy or Target, they don't understand RIP anymore or if they do, they also understand other routing protocols as well. Now the big difference between BGP and all the other Interior Gateway Protocols is that BGP allows you to route between Autonomous Systems instead of individual routers. I've got a diagram on the next slide that kind of makes that, make a little more sense, but essentially if you look at your next hop in BGP it's going to say, it's this Autonomous System and I don't care what router in that Autonomous System to connect to, it's just you have to go through that Autonomous System to get to your destination. Now the BGP holds the Routing Table for the entire Internet. The Routing Table is stinking huge if you look at some of the Internet providers that provide full routes to you. I mean, just think about how big the Internet is, it is a worldwide network of networks, you can imagine how big the routing protocol or the Routing Table is in the BGP Routing Protocol. Now obviously in our labs the Routing Table won't be that big because we'll just have, you know, five or six routers at the most. But just keep in mind that if you do ever find yourself in a situation where you're peering with an ISP and they're providing you full Internet routes or even partial Internet routes that you're going to have to a router that has quite a bit of memory, quite a big processor and is really probably the beefiest and biggest router on your network. So anyway I've talked about BGP and how it routes between Autonomous Systems and here's my example. This is the Internet, well not all the Internet, but it's, it's enough of the Internet and each of these Clouds that I have here represent an Autonomous System. This is Layer 3 and this is Vodafone and this is AT and T. Obviously there's more than three routers in each of these domains, but, but you get the point. So if you have a customer that's over here at AT and T and they need to get an address that's over here on Charter for example, well obviously your machines IP addresses right over here and so your machine is just hanging off this router right over here and there's, there's your little machine there. I'll draw a little box for your machine and it wants to get to the web server that's hanging off of this router over here. There's the web server over on this guy and yeah I can't draw. Well, obviously you have to know how to get from Point A to Point B so you just ask your ISP, hey how do I get there? You know, here, you're trying to get to the, you know, the IP address 12.36.45 for example or you're trying to get to that network anyway. Well you will eventually hit the edge of A T and T's network and here at A T and T's network, they'll have an edge router that runs BGP and has the Route Tables for all of these networks in it's BGP Table and, and it's installed in the Route Table. And so it will ask BGP, hey what's the best path to get to the 12.34.56 network? Well Charter over here will advertise, hey I've got that network, and you just send all of your packets my direction and I'll worry about how to get it to the actual router it's connected to, you just, you just send it to me. And to get there you go through this Autonomous System and then I'm directly connected to it. So it will send it's packets out through this Autonomous System. This Autonomous System will route it however it routes it internally and that's up to whatever Internal Routing Protocol, OSPF or EIGRP or whatever they're running internally in their system. It will eventually exit they're system and go over to the Destination AS. And the Destination AS will then route it using it's internal protocols to the actual router and switch that the host is connected to. And obviously this device over here does not know the actual IP address of the end router for the destination, it just knows, well I go to this AS and he handles it however he's going to handle it or routes it, you know, however he's going to route it in here. It eventually exits and goes over to this Autonomous System and so all I really need to know is that my destination is in AS you know, fifteen for example and I just send it that direction. We'll continue on with our discussion of our BGP overview in the next video.
Tutorial Information
| Course: | Implementing Cisco IP Routing (642-902 ROUTE) |
| Author: | Greg Dickinson |
| SKU: | 34291 |
| ISBN: | 978-1-61866-028-2 |
| Release Date: | 2011-12-28 |
| Duration: | 10 hrs / 105 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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