BGP-PART-2- Transit AS- Next hop Self.avi

hello and welcome this is Jay children in this video we are going to learn something about bgp transit autonomous system bgp transit autonomous system now when we have an autonomous system in the middle between two other autonomous systems and if we will allow traffic on the middle road middle autonomous system to pass traffic from one of a system on either side then we call that middle autonomous system as the transit autonomous system let me explain it no little bit more briefly we have our one own autonomous system 10 and we have our 600 over system 30 traffic between our world and our six if it will be permitted to pass via autonomous system 20 that is via our two or three or five or our 2 or 4 or 5 then this adorable system that is of BGP 20 is called as transit autonomous system now I drew the head if you see an R 5 on our 5 I am getting update from our 6 show IP BGP I'm learning in a tour called 6 6 66 66 66 from 30 dot 0 dot 0 dot 6 which is the next hop ebgp next stop which is our 6 I am learning there from the ebgp autonomous system 30 on an autonomous system 20 likewise if I see on our to show IP BGP I get live in dot 11.11 11 from my next hopper then his next autonomous system then is autonomous system till see autonomous system 10 from where I'm learning from autonomous system tale about 11.11 don't 11.11 in the previous example I am running from 30 that's why it is called as path vector protocol shows apart wire which it has learned it now but for this prefix has to go to the other side now this Levin should be sent to fine likewise 66 should be sent to dota 2 for that I should make r2 and r5 as a ibgp neighbor right so let me go and do it fast let me say router bgp 20 and then i'll say my neighbor is what is the let me give this IP address on fast and represent alert 0 on our Phi I'm on or 5 then let me give this IP address faster than 0 / 120 dot twenty-three dot 0.2 and remote ASIS same 20 all right now let likewise let me go to r2 and router bgp 20 neighbor is 30 dots not 30 when Indy dot 35 dot 0 dot 5 Nimmo Babli 20 they should form neighbor show IP VCB somebody yep neighbor respond right has come up now I got a neighbor I also have learned a network from the neighbor now if I type show IP be GP show IP BGP Here I am seeing 66 from where I'm learning 30.6 I'm running from 30 Hertz meaning I am running from another autonomous system about 66 but if you see here it is saying star as well as care it means you know varied as well as best but if you see here 66 it is only valid but not best why because this 30 dot 0 dot 0.6 cannot be reachable from here see I'm thinking 30 dot 0 dot 0 dot 6 I cannot reach I don't have a route at all we are not running or SPF on this because r2 don't know the route to reach 30 see show IP route because there is no route to reach 30 there is no 30 at all there is no route to reach 30 BGP says I learned from a neighbor yeah it's true but I cannot consider it as a best one should I be BGP it is not a best one but I learned somehow I learnt but it is not reachable so I am saying that is not a best one likewise on our fee also show IP BGP I learned lemon but because the next half adder has 10 dot 0 dot 0 dot just simply say it as a valid but not best right all right now next you know what we are going to see is how to make his autonomous system 20 is a transit autonomously now this is not transit if I ping from our world let me go to r1 and say show IP BGP I am not seeing this 166 at all I am not seeing at all now can I bring from wire word 66 no I cannot bring meaning I am NOT learning so I cannot pin this is not transit now Tran Sigma T it has to pass 66 to R word it is not passed why why it is not pass because it is not a valid and based on our 266 is not valid if it's if it is valid and based it would have passed it now our job is to make this word as valid in base right right so our job is to make it as valid and based there is also another way to do this what is that we already done who is PIP here we can redistribute this BGP do SPF and always be able to be GB and vice versa so that 66 will be advertised in - oh is PF OSPF will replicate up to r2 and r2 will again redistribute back to BG be back on r1 and r1 can see 66 this is one way but not recommended way right what I was saying is this rate is different bTW BGP in to nigp here we have OSPF running on all this for outers but not on this interface that is connecting to ebgp not on 10 and 30 we ran over sphere and only only the inside interface of almost all to it but not recommended why that radius severe process will take a lot of process that radius avoiding from bgb to OSP from a big protocol with lot of attributes to a small protocol like OSPF when you come back to bgp is small it takes a lot of process so for this reason that it is not recommended another thing bgp comes with lot of attributes when you redistribute all attributes will be canceled so for this reasons it is not a recommended way so what is the solution we need to make it fully meshed that is the best solution redistribution is not a best solution making it as fully meshed is what no recommended solution right but by default route learns to latvia ibgp will never be propagated to other ibgp so that's what we are going to learn now you know I'm going to show you in some time I'm going to make r2 and r3 s neighbor like Miss r2 and r4 s neighbor only directly connected as neighbor CLI will complete do it go to r2 and say router bgp 20 my neighbor s 28 our 23 dot 0.3 remote is 20 this is one neighbor another neighbor is 24 right so 20 4.00 the 24.4 yep likewise we will do an r3 as well as March 4 I'll use a notepad so pistolas choice all right I'm doing this for now out of three so I will say 23.3 is one neighbor so when 35.5 okay just cut and paste this on our three then likewise for our for our four I will have 24.3 not too I think I made a mistake in previous router good our three has neighborhood 23.0 not too it is not three 23.2 alright now here 24.2 and then 45.5 router for now on our five I need to say 35.3 and here to be 45 dot or this is what on our five and also I'm going to remove the statement which we gave previously we made our fine are to his neighbor no let me remove it now what I what we have is fully meshed let's see first without fully mission then it's fully washed right now okay we will finish with full image once left because it's already ready show IQ bgp still I don't have let it or learn 11.11 as valid it how and based but if you see an r3 r3 has learned both show IP v GP it has done both but both or not valid as well as best way same reason r3 don't know how to reach since 30.6 r3 don't know how to reach entered level what we have solved right now is black hole we have solved what is that previously r3 and r4 we're not aware of this through network now it has learnt it but still it is not very done based making it as varied and based is different concept material into the next now we have somehow brought these prefixes from various autonomous system into r3 and r4 now what I would like to do is I would like to break that fully meshed I want to make it as partially break I want to show you the difference router bgp 20 and say no neighbor no neighbor 20 dot twenty-three dot zero dot two remote now it is partially meshed so I will be GP I don't have lemon it won't come so it should be fully meshed if you want to receive updates from another a BGP into this VV GP it should be fully meshed let me put it back router bgp 20 neighbor okay now I would like to do finally finish neighbour is what 20 dot twenty-three dot zero dot two remote is yes twenty now this will form neighbor again and we should see the updated BGP table now if I type show at BGP I should see Levin coming back again now how can you make this as valid as well as best very simple now router five instead of saying 66 I learned from 30.6 if it says it is me the one who is saying see it is running from where 66 it is learning from 30.6 now if you go to r3 and see that it says 66 I am learning from 30.6 mean you know I am NOT learning from immediate directly connected neighbor I am learning from remote neighbor who is in different autonomous system right this belong to autonomous system 20 but it is learning from 30 which is not reachable same story here also 10.1 is not reachable for this router we do not run voice peer so instead of r5 saying that you know 30.6 if it will say 20 dot thirty five dot zero dot five problem solved see our five instead of saying to our three thirty dot 0 dot 0 dot 6 is the source instead of saying that if it will say 20.25 dot 0.5 as a source i michael be the source problem solved now how to do that go to r5 router bgp 20 right router bgp 20 who are the neighbor neighbor 20 dot thirty five dot zero dot 3c to this neighbor it needs to say make stop itself what it means I am the next top self I myself is the next house now when I say this what happens I am taking you to that three-rotor so whenever you do such changes it is good okay fine and it's come right sometime if it is not immediately coming you need to use this command what is the word a refresh command out of the fresh clear IP BGP you can precisely say the neighbor number or you can say star visit star so it will do what it will refresh it will it will establish reestablish see now instead of saying 30 dot 0 dot 0 dot 6 it says 20 not 35 it is it is reachable that's what is valid and based now if I will go to our to show IP BGP I have I am not having 6 2 6 s still I am not having 66 as valid and based why you know this 66 it is not learning really from r3 it is learning from home r5 so I need to go back to our file here also I need to say what next top self for reach neighbor for this neighborhood 20 dot twenty-three dot zero dot two that neighbor also I myself is the next stop now if I will go I have added in best are three is also having now wear it and best for 66 if it is valid and best then I can also see in routing table show IP route see in routing table you won't find leaven why it is just married but you should see what 66 you are not seeing living so how can I get living on our two outer BG b20 my neighbor is xx dot twenty-three dot 0.3 next hop likewise we have another neighbor 35 you 5.5 35.5 next hop self now when I do this I will see on our three live in drought see lemon drought has come so if it is true then our five old so I should see lemon drop yep when you see lemon now if that is true then our six also should have live in show IP BGP should I be ro okay so I be BG first it says live and I am learning I am running from home 30-knot five this is good and sixty-six I myself is leaning stop right now show IP route I should see you hope to reach 11 traceroute clement xi dot 11.11 goes to this router okay let's stress from left to right in order to go to 66 network router one says I need to go to 10.2 so if you go to 10.2 let us go to tender to rotor which is all to show IP route 66 such 6.66 tar 66 this says in order to go to 66 Network I need to go to 20 yards 35 dot 0.5 right I need to go here it says now let us see the route show IP route okay ready so show me the route to reach that it says I need to go to the router 3 now let us go to an outer 3 show IP No now this says in order to go to 66 I need to go to 20 dot twenty or thirty 5.0 at five so that is what this router is all about so if it is if it will come to r5 r5 will easily deliver to our 6 a route is there actually right but I couldn't trace on pink and show you because of some bugs in this tool so this we learned that in order to make an autonomous system as a transit autonomous systems we need to have fully meshed redistribution is not at all a recommended death way up doing so when we do fully meshed and we may say next up cells we got the routing it says show IP route we got route on the other side yes 11 we have learned on our six right now two things we learned in this one is it should be fully meshed another one is next of self comment to make a valid prefix to be valid as well as best wear it as well as best we need to type next top self come in right so further more advanced concept in the next video thanks for watching

Channel: Jayachandran

Views: 11,341

Keywords: Transit, AS, Next, hop, Self, BGP

Id: coNYPLNXm6w

Length: 26min 57sec (1617 seconds)

Published: Sun May 06 2012