There this is Habib again. And I'm back. As we know, in chapter one I introduced BGP, we talked about facts of BGP. In our introduction chapter. In chapter two, we we did our first topology in BGP, where we actually establish ibgp peering and ebgp peering. We talked about split horizon rule, and how it's used to basically guaranteed Loop The Loop free routing.
But at the same time, it may cause a hindrance, because you want to still have certain routes to be learned by the neighboring routers. So there are ways to mitigate that and one of them is actually explained here in chapter Tree topology to where I will be explaining BGP configuration. BGP configuration helps with ibgp meshing, they are used instead of Route reflectors. Route reflectors is another method which is basically almost simpler than the BGP configuration. BGP configuration. Basically what it does is it splits the autonomous system, let's say hundred in our case where all the routers were part of the autonomous system hundred.
But in here, it splits the four routers into into smaller autonomous systems that are more manageable. And yet still, the ebgp routers will still think that they are communicating with a single entity with a single autonomous system. So, let's start I hope you will benefit from this chapter a lot because we are moving into more advanced techniques and I hope this will help you in your real world work environment where you will have to create BGP and neighboring and peering. So, this is only one of the ways to do it and and also in this lab what we will do is we will introduce OSPF and as I said within the within the same autonomous system routers you can actually run interior routing protocol. OSPF is one of them. So, we will see how we will introduce OSPF in this topology.
One thing that I would like to do is the on our to the interface which is F Zero slash zero that's connected to our five for OSPF that interface should be actually passive interface on the external link which is F Zero slash zero and but the routers the passive is configured so that if R five runs OSPF on the same link, it will not establish an OSPF adjacency basically with our two okay. And and it will have all the information on all the private IP addresses advertised in as 100. So you don't want basically a neighboring external hard routers establishing a relationship and learning about routing information from 100. So this is the this is basically the summary of our topology. Now let's move on into the configuration and and we will continue from there.