Bgp border gateway protocol has been added to the CCNA so it's important that you have an understanding of the protocol and know how to configure a basic topology with BGP BGP is a very large subject and you can spend a lot of time learning the ins and outs of BGP however for the CCNA it's very much an introduction to BGP when looking at the CCNA exam topics in this case for the 200 - 125 exam we can see that one of the exam topics is configure and verify single home - branch connectivity using ebgp IP version 4 the exam is limited to peering and route advertisement using the network command only so again BGP is a very large topic I'm going to explain a little bit more where I show you the configuration of both I BGP and ebgp the configuration is essentially exactly the same at CCNA level in this genus 3 topology I have two autonomous systems sixty-five thousand and one and sixty-five thousand and two I'm using public IP version 4 addresses in this topology you can see the list of assigned / 8 ipv4 address blocks on Wikipedia so in our topology I'm using Network eight which belongs to level three I'm using Network 15 which belongs to HP and I'm using Network 17 which belongs to Apple so Apple are connecting through level three to HP in this topology I've configured IP addresses on these routers but nothing else so show IP protocols BGP is not enabled on this router and neither are a GPS or interior gateway protocols such as AI jarppi and OSPF BGP is an exterior gateway routing protocol in other words it allows for communication between autonomous systems OSPF and EIGRP would run within the autonomous systems hence they called a GPS or interior gateway protocols so on Rider one router bgp we need to choose an autonomous system number in this example I'm going to choose autonomous system number sixty five thousand and one BGP unlike other writing protocols requires the configuration of a neighbor you have to manually and explicitly specify your neighbor relationships they're not formed automatically like they would be in OSPF EIGRP so this example we need to specify that seventeen 1.1.2 is a neighbor and we use the command remote is to specify the autonomous system number of the neighbor even though they both within the same autonomous system we still use the remote AAS number so I bgp or interior BGP and ebgp or external BGP both use the remote is number command we need to advertise routes in BGP and to do that we'd use the network command now this uses a standard mask and not an inverse mask and it's really important that you have your masks set right show IP BGP the show IP BGP command shows us that the BGP table version is 2 BGP has its own routing table so it has that