BGP Introduction - Video By Sikandar Shaik || Dual CCIE (RS/SP) # 35012

[Music] welcome to BGP video trainings now in this section we'll start with some of the basics of BGP like basic concepts and terminology so if you just try to look into the basic things what we are going to see first we'll start with autonomous system number what is autonomous system number and then we'll see the differences between igb and HP protocols some of the basic features of BGP and then we'll see the loop prevention mechanism in the BGP and then finally we'll wrap up this video by understanding when it is more appropriate to use PGP and when it is not really recommended to use BGP so let's get started first with autonomous system number now from our basic CCNA studies we already learn what is autonomous system number autonomous system number is simple it's a collection of networks under a single common administrative domain so that's what we say it's a collection of routers under a single administrative domain like take an example I go to an organization where it has a specific location and all or part of the same organization let's say it is a s number 100 and this organization is let's say ABC and all the routers within that organization will be represented with one number and we call that as autonomous system number okay now the next thing is like similar way we can have multiple autonomous system numbers and if you want to communicate within the same autonomous system number or within the same organization generally we use IGP protocols like whatever the protocols will learn in our previous videos in the basic CCNA ccnp videos so we call as our IP our IP version two idrp no more used EA GRP o SP of ISS these are all igb protocols so the main difference is IP protocols operates within the same autonomous system number so if you want to communicate within the same organization or same autonomous systems then we use something called interior cater protocol they call them as ITP protocols so all these protocols listed here they are typically your ICP protocols but let's say if you want to communicate between two or more different autonomous system numbers then we use an exterior gateway routing protocol and the only protocol which is running on the Internet which is allowing you to exchange the route between two or more different autonomous system numbers is btv protocols so BGP is the only protocol which is running in the Internet backbone and which is majorly responsible for maintaining the route for exchanging the routes between the two or more different sub autonomous systems and the service folders use PGP protocol and by using BGP they control all the routing information so BGP is the only protocol which is designed to for a huge huge network that is internet so we'll see some of the points anyway more into that more in detail about the BGP features in this section we have seen the autonomous system number it suggests a red routers under a common administration now if you are communicating between two or more different autonomous system numbers like we are trying to see exchange route between two or more different organizational members we use a protocol called BGP ok so next thing what we'll see we'll get into ICP routing like when we talk about IGP routing we have seen static default and dynamic routing and inside that dynamic routing we have seen our IP EHR POS p of is all this protocol all these protocols operate within the same autonomous system numbers so we call them as IGP protocols but if you want to communicate between two or more different autonomous system numbers we use a big heavy protocol so first we'll start with some of the basic features of BGP like PGP is a standard protocol you can run this protocol and any vendor device and it is an exterior gateway routing protocol exterior in the sense it is going to exchange the route between two or more different autonomous it remembers so we call it as exterior gateway protocol and it is specially designed for inter domain routing interest means communication between two or more different autonomous system numbers let's say this is a 100 want to communicate with a s200 like I got a previous diagram between these two is we use bgp protocol and is specially designed to scale a huge internet work like Internet it supports classless and then it's suppose all yours fellas simulation CIDR manual and auto summarizations all these things will separate in the BGP just like we have in all over hi GP protocols and it's similar to your internal protocol updates or incremental and trigger update feel supported and we call BGP as a path vector protocol now what what is mean by prospectus so path vector is a method of extending the routes along with a path information like like take an example here I got I got a diagram here you can see the diagram here now let us take an example this router is going to advertise this 10.1.1.1 it works so now this router is going to advance this network into the next autonomous systems which means it is going from one a is to another is so it is going to carry that 10.1.1.1 and at the same time it is going to carry the AA's path information so it is coming from which is so 65,000 and 400 is now when it sends it is going to pass on this information to this router and when this router is going to pass on the information to next starter or next autonomous systems it is going to carry that network information just like your normalizable protocol but it is going to carry the autonomous system path information so it's going to say that it's coming from 65 400 that is this a s and then it is going to this it is coming from this two ways it's crossing these two autonomous systems and reaching here and finally when this router is going to send it to other router it is going to pass on that information like it is originating from this s and then it has reached the next phase and then finally it has reached this is and last is so we call this as a path information and when it is going to carry any routing update it's going to make sure that it is going to carry this autonomous system pass information now this is very useful especially when you are very efficient in a loop prevention mechanism there is something called loop remission mechanism which I will be discussing in our next video next sections probably I'll get into that more in detail okay so we call it as path vector protocol where it is going to carry the path information from which autonomous system hops it is moving on so that is one of the one of that's the reason we call as path vector protocol and then some more differences some more features of BGP it sends updates to manually neighbors using unique ask so this at this point I will get into more clear when I get into BGP neighbors now this point will tell that like manually you have to compare the neighbors now what is manually let's take an example we got two routers and if I am running OSPF protocol or any other protocol let's say eh ARP protocol by default when you have dies this interface it is going to send a hello message to the other side of the interface and then it is going to reply to that hollow message based on that hello messages they automatically establish the neighbor ship so they will automatically become the neighbors and they automatically build a neighbor table there is something automatic neighbor ship but in BGP we don't have that in BGP we have to manually configure the name of which means we need to say that router - you are my neighbor it says this router one auto - on the router one you have to configure a neighbor command saying that you are minimal and on the router - you have to configure the neighbor command saying that router one is the neighbor of router 2 and if both the sides neighbor commands matches if everything is properly configured then you will find the neighbor ship comes up that's what manual neighbor ship configurations we got some initial laps majorly dedicated on this I'm not getting into practical things probably in our next couple of videos in the third or fourth video probably will directly jump to this lab where I will also show you the point raishin how it goes and some more detail on whatever we discussed the next thing it's a busy piece application layer protocol for reliability it uses TCP protocol it works on port number 179 and the metric metric it uses a lot of action boots so we got a weight attribute local preference and here's pass origin next up we got a lot of attribute bgp supports very easy emotive attributes which can affect the path manipulation process like in OSPF it uses bandwidth and the default formula it uses is ten to the power of eight divided by bandwidth in case of EHR p it is going to use bandwidth delay load into your reliability in case of our IP it is going to use hopkins but in bgp the path selection process where is and it's majorly on this attribute so more on these attributes will definitely get into this in our advanced bgp concepts so as of now I can simply say that it supports rich attributes which can really affect the path manipulation and then finally administer distance is 20 if the route is coming from external bgp again we'll see the differences of external bgp and I can tell me TP also if the route is coming from external bgp or from a different autonomous system that will have the admission distance of 20 if the route is coming from the same is that's what we call as internal BGP we have the administered distance of 200 so again more in detail about I BGP and BGP I will be definitely covering in detail in our next section so here I am just getting into some basic information which is going to define the features of BGP so like if you remember just now I discuss loop prevention mechanism in BGP now there is a possibility like you are connecting to internet and you're connecting your service folder from one side and probably you're connecting to another service port or from the other side so you may be authorizing your route let's attend on network and this route is addressed to a service forwarder or it can be able to us to some other autonomous system and from there it reaches the internet cloud and from this there is a possibility of the same not coming back again now that will again create the loop but in BGP there is a rule that whenever a router sees its own AAS number like if you remember just now I discussed the path vector behavior like take an example I got this network 180 dot 10.0.0.0 this network is originating from a is 100 when it sends to the L router the second a is or the next days it is going to carry the network information like one 80.000 or 10.000 whatever it is and it is going to carry the autonomous system path information saying that it is coming from 100 and from this when it reaches the other is now the same network 180 dot 10.0.0.0 slash 16 it is going to carry the ACE path information that it is coming from 100 here and then reaching 200 and then final is reaching timaeus and when this is it is going to forward it to a is find it is going to forward that network information with 180 0 0 0 slash 16 and it's going to say that it's coming from 100 so in the other it will be reverse and then it's reaching a is 200 here and then coming to 300 so which means now this routers will understand inside these routers in a is 500 they will understand that this network is coming from 100 and then going to 200 and then coming to 300 finally reaching to my autonomous system number now after this from here this is again advertised back way is 100 now when it is going to organize this information now when a router receives this information it is already running a is 100 and whenever it sees its own a is number inside that update it's not going to accept the route so this is the default loop prevention mechanism in BGP protocol whenever a routers like you can see one eighty eight or ten dot network is not accepted by s 100 as a prefix as is in its path this is a loop detection in action default loop prevention mechanism in the beach be so BGP will never install any route when it sees its own ace member so I'm running is 100 and I'm getting a route content or network which also has a is 100 so it's something originating from is and coming back to my again so because when you are connecting to internet definitely you are connecting to multiple routes and there is a possibility that the routes will be coming from multiple sites or the same route is coming back again to my ace so this is something loop dimension mechanism you need to understand the default behavior of the BGP [Music]

Channel: Sikandar Shaik

Views: 303,488

Rating: 4.8515282 out of 5

Keywords: bgp, bgpvideos

Id: G0qDnqOKwOE

Length: 14min 23sec (863 seconds)

Published: Mon Feb 27 2017